Soil-mediated Drivers of Coupled Biogeochemical and Hydrological Processes

Across Scales

Biosphere II, Tucson, Arizona, USA | 21–24 October 2013

AGU Chapman Conference on Soil-mediated Drivers of Coupled Biogeochemical and Hydrological Processes

Across ScalesBiosphere II, Tucson, AZ, USA

21–24 October 2013

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Note: Attendees at the Chapman conference may be photographed by AGU for archival and marketing purposes. No photography will be permitted during scientific sessions.

Program Committee

Dani OrEldenösslsche Techische Hochschule Zurichdani.or@env.ethz.ch

Yakov PachepskyU.S. Department of Agricultureyakov.pachepsky@ars.usda.gov

Nicolas BrüggemannForschungszentrum Jülich GmbHn.brueggemann@fz-juelich.de

Scott FendorfStanford Universityfendorf@stanford.edu

Ty P.A. FerréUniversity of Arizonaty@hwr.arizona.edu

Karsten Høgh JensenØster Voldgrade Department of Geographyof Geologykhj@geo.ku.dk

Hans Peter SchmidInstitute of Meteorology and ClimateResearch Atmospheric EnvironmentalResearchhape.schmid@kit.edu

Donald L. SparksUniversity of Delawaredlsparks@udel.edu

Kurt RothUniversity of Heidelbergkurt.roth@iup.uni-heidelberg.de

Matthew WallensteinColorado State UniversityMatthew.wallenstein@colostate.edu

Asmeret Asefaw BerheUniversity of California, Mercedaaberhe@ucmerced.edu

Conveners

Harry VereeckenAgrosphere Instituteh.vereecken@fz-juelich.de

Michael YoungThe University of Texas at Austinmichael.young@beg.utexas.edu

Peter TrochScience Director Biosphere 2 The University of Arizonapatroch@hwr.arizona.edu

Paul M. BertschUniversity of Kentuckypaul.bertsch@uky.edu

Poster Presentation Guidelines

Poster sessions are active on Monday, 21 October, 5:00 P.M.-6:30 P.M., and Tuesday, 22October, 4:00 P.M.-6:00 P.M.

The poster dimensions are 4 feet high by 8 feet wide. The size of posters should be not morethan 4 feet wide by 4 feet wide to allow two (2) presenters to utilize one posterboard on eachside. All boards will be marked with the appropriate poster number and category.

Those presenting their posters on Monday are asked to set up their posters on Sunday, 20October. Posters must be removed by 6:30 P.M. on Monday, 21 October.

Those presenting their posters on Tuesday are asked to set up their posters on Tuesdaymorning, 22 October before sessions resume. Posters must be removed by 6:00 P.M. onTuesday, 22 October.

Basic poster supplies will be available for your use. If you have special supply needs, pleaseremember to bring them with you to Biosphere 2.

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Thank You to Our SponsorsThe conveners wish to acknowledge the generous support for this conference

from our sponsors.

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AGU Chapman Conference on Soil-mediated Drivers of Coupled Biogeochemical and Hydrological Processes

Across Scales

Meeting At A Glance Sunday, 20 October6:00 P.M.-6:30 P.M. Welcome Reception (B2 Café/Patio)6:30 P.M.-7:30 P.M. Dinner (B2 Café/Patio)

Monday, 21 October 7:00 A.M.- 8:00 A.M. Continental Breakfast (B2 Café/Patio)8:00 A.M.- 8:05 A.M. Welcome Address: Joaquin Ruiz, Director, Biosphere 2 and Dean, College

of Science (Sahara)8:05 A.M.- 8:30 A.M Introduction by Conveners (Sahara)8:30 A.M.-10:00 A.M. Session I: Coupled Abiotic-biotic Drivers of Organic Matter and Nutrient

Transformations and Transport Across Terrestrial-aquatic Interfaces I(Sahara)

10:00 A.M.-10:30 A.M. Morning Break (Sahara)10:30 A.M.-12:00 P.M. Session II: Coupled Abiotic-biotic Drivers of Organic Matter and

Nutrient Transformations and Transport Across Terrestrial-aquaticInterfaces II (Sahara)

12:00 P.M.-1:30 P.M. Lunch (B2 Café/Patio)1:30 P.M.-3:00 P.M. Session III: Gas Flux Exchange in Soil-Plant Systems I (Sahara)3:00 P.M.-3:30 P.M. Afternoon Break (Sahara)3:30 P.M.-5:00 P.M. Session IV: Gas Flux Exchange in Soil-Plant Systems II (Sahara)5:00 P.M.-6:30 P.M. Poster Session (Lower Habitat Plaza)6:30 P.M.-7:30 P.M. Dinner (Lower Habitat Exhibit Hall)

Tuesday, 22 October7:30 A.M.- 8:30 A.M. Continental Breakfast (B2 Café/Patio)8:30 A.M.-10:00 A.M. Session I: Monitoring Strategies of Soil-mediated Processes and Drivers

from Local to Catchment Scales over Time I (Sahara)10:00 A.M.-10:30 A.M. Morning Break (Sahara)10:30 A.M.-12:00 P.M. Session II: Monitoring Strategies of Soil-mediated Processes and Drivers

from Local to Catchment Scales over Time I (Sahara)12:00 P.M.-1:30 P.M. Lunch (B2 Café/Patio)1:30 P.M.-3:30 P.M. Breakout Sessions (Sahara Room, B2 Café Patio, Gobi Room, High Rise

Gallery, Casitas 1900 and 500)3:30 P.M.-4:00 P.M. Afternoon Break (Sahara)4:00 P.M.-6:00 P.M. Poster Session (Lower Habitat Plaza)6:00 P.M.-7:00 P.M. Dinner (Lower Habitat Exhibit Hall)

Wednesday, 23 October7:30 A.M.- 8:30 A.M. Continental Breakfast (B2 Café/Patio)8:30 A.M.-10:00 A.M. Session I: Soil Resource as a Primary Driver of Ecosystem Services I

(Sahara)10:00 A.M.-10:30 A.M. Morning Break (Sahara)10:30 A.M.-12:00 P.M. Session II: Soil Resource as a Primary Driver of Ecosystem Services II

(Sahara)12:00 P.M.-1:30 P.M. Lunch (B2 Café/Patio)1:30 P.M.-3:30 P.M. Visit to Landscape Evolution Observatory, Biosphere 2, or Free Time3:30 P.M.-4:00 P.M. Afternoon Break (Sahara)4:00 P.M.-6:00 P.M. Breakout Sessions (Sahara Room, B2 Café Patio, Gobi Room, High Rise

Gallery, Casitas 1900 and 500)6:00 P.M.-8:00 P.M. Conference Banquet (Lower Habitat Exhibit Hall)

Thursday, 24 October7:30 A.M.- 9:00 A.M. Continental Breakfast (B2 Café/Patio)9:00 A.M.-10:30 A.M. Group Reporting and Synthesis (Sahara)10:30 A.M.-11:00 A.M. Morning Break (Sahara)11:00 A.M.-12:30 P.M. Wrap-up in Plenum12:30 P.M.-1:30 P.M. Lunch (B2 Café/Patio)1:30 P.M. Adjourn

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SUNDAY, 20 OCTOBER

6:00 p.m. – 6:30 p.m. Welcome Reception

6:30 p.m. – 7:30 p.m. Dinner

MONDAY, 21 OCTOBER

7:00 a.m. – 8:00 a.m. Continental Breakfast (Monday)

8:00 a.m. – 8:05 a.m. Welcome Address: Joaquin Ruiz, Director, Biosphere 2and Dean, College of Science

8:05 a.m. – 8:30 a.m. Introduction by Conveners

Coupled Abiotic-biotic Drivers of Organic Matter andNutrient Transformations and Transport AcrossTerrestrial-aquatic Interfaces I - OralSahara Room

8:30 a.m. – 9:00 a.m. Claudia M. Boot | Linking Lability and Composition of DissolvedOrganic Matter Across the Terrestrial-Aquatic Interface (Invited)

9:00 a.m. – 9:15 a.m. Rebecca Martin | Hydrologic Controls of DOM Export FromAgricultural Soil to Surface Water via Tile Drainage: The Roles ofFlow Path and Processing

9:15 a.m. – 9:30 a.m. Eve-Lyn S. Hinckley | The Critical Zone as a Driver of Ecosystem NRetention and Transport in the Colorado Front Range

9:30 a.m. – 10:00 a.m. Jonathan Sanderman | Linking soils and streams: production,consumption, transformation and export of dissolved organicmatter in two contrasting watersheds (Invited)

10:00 a.m. – 10:30 a.m. Morning Break (Monday)

SCIENTIFIC PROGRAM

Coupled Abiotic-biotic Drivers of Organic Matter andNutrient Transformations and Transport AcrossTerrestrial-aquatic Interfaces II - OralSahara Room

10:30 a.m. – 10:45 a.m. Philippe Baveye | Fate of terrestrial carbon: We need to start at themicroscopic scale

10:45 a.m. – 11:00 a.m. Taniya Roy Chowdhury | Role of Geochemical and MicrobiallyDriven Processes in Carbon Dynamics in Arctic Ecosystems

11:00 a.m. – 11:30 a.m. Rose M. Cory | Going to the dark side: a novel pathway for abioticoxidation of dissolved organic matter in arctic soil waters (Invited)

11:30 a.m. – 11:45 a.m. Jessica Davies | Modelling Nutrient Transformations Through TheCritical Zone: From Atmosphere To Plants, Soils To Stream At TheRegional Scale

12:00 p.m. – 1:30 p.m. Group Lunch (Monday)

Gas Flux Exchange in Soil-plant Systems I - OralPresiding: Nicolas Bruggemann, Peter A. TrochSahara Room

1:30 p.m. – 2:00 p.m. Markus Reichstein | Soil, climate extremes and the carbon cycle(Invited)

2:00 p.m. – 2:30 p.m. Dan Yakir | Carbonyl sulfide (COS), a tracer to separate soil formcanopy CO2 exchange (Invited)

2:30 p.m. – 2:45 p.m. Kadmiel Maseyk | Soil, plant and ecosystem COS fluxmeasurements: observations of a new tracer of the carbon cycle

2:45 p.m. – 3:00 p.m. Claire L. Phillips | Using Radiocarbon to Investigate SoilRespiration Impacts on Atmospheric CO2

3:00 p.m. – 3:30 p.m. Afternoon Break (Monday)

Gas Flux Exchange in Soil-plant Systems II - OralSahara Room

3:30 p.m. – 4:00 p.m. Jerome Ogee | Global estimates of land photosynthesis inferredfrom the global budget of 18O in atmospheric CO2: the crucial roleof soil microorganisms (Invited)

4:00 p.m. – 4:30 p.m. Lisa Wingate | Seasonal contribution of soil CO2 invasion to thetotal CO18O flux from a pine forest ecosystem (Invited)

4:30 p.m. – 4:45 p.m. David D. Breshears | Beyond the Big-leaf Homogeneity Assumptionin Evapotranspiration Partitioning: Factoring in Canopy CoverHeterogeneity

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4:45 p.m. – 5:00 p.m. Sadredin Moosavi | Use of a Selective Inhibitor Technique RevealsControls on Hidden CH4 Biogeochemical Cycling Along SoilMoisture Gradients From Wetland to Upland in Boreal & ArcticSoils

5:00 p.m. – 6:30 p.m. Coupled Abiotic-biotic Drivers of Organic Matter andNutrient Transformations and Transport AcrossTerrestrial-aquatic Interfaces - PostersLower Habitat Plaza

M-1 Ling Ou | Carbon sequestration of Louisiana crawfish pondssediment

M-2 Deb Jaisi | A REVERSE PATHWAY OF PHOSPHORUS CYCLINGIN AGRICULTURAL SOILS

M-3 Kizhur Sandeep | Soil-Sediment Linkages in the Catchment area ofLakes in Southern India

M-4 Michael Schmidt | Geochemical tools to infer charring temperature,aromaticity and the degree of condensation of fire-derived organicmatter in soil, water, and sediment - a method comparison

M-5 Praveen Kumar | Passive Regulation of Soil Biogeochemical Cyclingby Root Water Transport

M-6 Owen P. McKenna | Geomorphic controls over Nitrogen andCarbon Stocks in Desert Playas

M-7 Linda H. Pardo | A hydropedological approach to identifyingsources and sinks of nitrogen in a steep, headwater catchment usingnitrogen and oxygen isotopes

M-8 Steven Hall | Synergies Among Oxygen and Iron in the CarbonCycle of Humid Tropical Forest Soils

M-9 Steven Sadro | The influence landscape position and catchmentcharacteristics on the biogeochemistry of high-elevation lake-chains

M-10 Scott W. Bailey | Influence of landscape position and transientwater table on soil development and carbon distribution in a steep,headwater catchment

M-11 Michael Nguyen | Probing Temperature-Dependent Organo-FeOxInteractions Using Quartz Crystal Microgravimetry, NMRSpectroscopy, and Thermal Analyses

M-12 Carrie-Ellen Gabriel | Examining physical and biological controls ofSOM stability through depth in harvested red spruce forest soils

Kate M. Buckeridge | Spring thaw vegetation leachate does notstimulate soil microbial activity in Arctic thermokarst soils

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M-13 Asmeret A. Berhe | Erosion of soil carbon and nitrogen in low-order catchments in the Sierra Nevada

M-14 Dragos G. Zaharescu | Role of Ecosystem Development in RareElements Cycling in an Ultra-oligotrophic System at Biosphere-2

M-15 Ciaran J. Harman | PERTH and the Dynamic Age Function: Atheoretical and experimental framework for understandingresidence and transit times in transient, complex flows

M-16 Jennifer K. Presler | Chemical Signatures of Biological Colonizationin a Model Ecosystem

M-17 Joshua Koch | Runoff sources and flowpaths in a partially burned,upland, boreal catchment

M-18 Fox Peterson | Forest Composition links Soil SOM and DOC toANPP in Complex Terrain

M-19 Rebecca Lybrand | Climate and landscape position controls on soilcarbon cycling in the Santa Catalina Critical Zone Observatory

M-20 David P. Huber | Climate Controls on Soil Hydrological andNutrient Partitioning in Dryland Ecosystems

5:00 p.m. – 6:30 p.m. Gas Flux Exchange in Soil-plant Systems - PostersLower Habitat Plaza

M-21 Zhongwen Bao | Numerical Analysis on the Factors Influencing theSoil/Atmosphere Diffusive Exchange of Persistent OrganicCompounds

M-22 Darin J. Law | Evapotranspiration Partitioning: Competitionbetween abiotic and biotic components of the water budget

M-23 Guo-Yue Niu | A Microbial Enzyme Based Soil Organic Carbon(SOC) Decomposition Model for Use in Climate Models

M-24 Zachary M. Subin | Representing the Effects of Hillslope-ScaleHydrology on Soil Carbon Distributions within an Earth SystemModel

M-25 Samuel Dunn | Production, consumption, and transport ofmethane in alpine and sub-alpine wetlands as a function of plantspecies

M-26 Laura Gangi | Identifying and quantifying determinants of theoxygen isotopic exchange between soil water and CO2 by combininglaser-based spectroscopy and gas-permeable tubing

M-27 Stephan Glatzel | Methane controls the greenhouse gas budget ofrewetting fens

Anne E. Kelly | Deep soils allow anomalously high productivity andlimit summer drought stress in California conifer forests

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M-28 Luke A. Pangle | Climate-warming impacts on water and carbonfluxes in a seasonally semi-arid grassland ecosystem

M-29 Katherine M. Powell | Links between soil water availability and soilrespiration in semi-arid ecosystems along the Colorado FrontRange

M-30 Shiliang Wu | Interactions between Anthropogenic and SoilEmissions of Nitrogen Oxides

6:30 p.m. – 7:30 p.m. Dinner (Monday)

TUESDAY, 22 OCTOBER

7:30 a.m. – 8:30 a.m. Continental Breakfast (Tuesday)

Monitoring Strategies of Soil-mediated Processes andDrivers from Local to Catchment Scales Over Time I - OralPresiding: Yakov Pachepsky, Harry VereeckenSahara Room

8:30 a.m. – 9:00 a.m. Guenter Bloeschl | From the local to the catchment scale:challenges and ways forward (Invited)

9:00 a.m. – 9:30 a.m. Jeffrey J. McDonnell | The importance of boundary conditions onwater flow and residence time at the hillslope scale (Invited)

9:30 a.m. – 9:45 a.m. Willemijn M. Appels | The role of soil depth, bedrock permeability,and lateral flow on hillslope groundwater recharge patterns

9:45 a.m. – 10:00 a.m. Mark S. Seyfried | Soil Temperature and Water Dynamics onContrasting Aspects in the Rain-Snow Transition Zone at ReynoldsCreek

10:00 a.m. – 10:30 a.m. Morning Break (Tuesday)

Monitoring Strategies of Soil-mediated Processes andDrivers from Local to Catchment Scales Over Time II - OralSahara Room

10:30 a.m. – 11:00 a.m. James W. Kirchner | Universal fractal scaling in stream chemistryand its implications for solute transport and water quality trenddetection (Invited)

11:00 a.m. – 11:30 a.m. Peter A. Troch | The Landscape Evolution Observatory (LEO) atBiosphere 2: Opportunities for collaborative Earth system researchin a controlled environment (Invited)

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11:30 a.m. – 11:45 a.m. Jessica M. Driscoll | Role of storage on hydrologic and chemicalflux in soil-limited alpine catchments in the Southwestern USA

11:45 a.m. – 12:00 p.m. Christoph Hinz | State transitions in the artificial catchmentHuehnerwasser (Chicken Creek): Ecosystems development 8 yearsafter initialisation

12:00 p.m. – 1:30 p.m. Group Lunch (Tuesday)

1:30 p.m. – 3:30 p.m. Breakout Sessions (Tuesday)Sahara Room, B2 Café Patio, Gobi Room, High Rise Gallery, Casitas 1900 and 500

3:30 p.m. – 4:00 p.m. Afternoon Break (Tuesday)

4:00 p.m. – 6:00 p.m. Monitoring Strategies of Soil-mediated Processes andDrivers from Local to Catchment Scales Over Time - PosterLower Habitat Plaza

T-1 Wolfgang Schaaf | Using the constructed catchment Chicken Creekto disentangle feedbacks between soils, surface structures,vegetation and hydrology during initial ecosystem development

T-2 Michael P. Stockinger | Active Catchment Area as a ControllingFactor of Spatial Patterns of Transit Time Distributions in a Small,Forested Catchment

T-3 Adrian A. Harpold | Snowmelt Infiltration Dynamics in SeasonallySnow-Covered Areas of the Western U.S

T-4 Colin S. Campbell | Effects of changing rainfall patterns on soilmoisture storage and plant canopy dynamics in a subalpine meadow

T-5 Damiano Pasetto | Soil water potential assimilation to reconstructsaturated hydraulic conductivity at the Landscape EvolutionObservatory

T-6 Sebastian Gebler | Modelling soil moisture patterns with ParFlow-CLM: A comparison of high resolution model simulations with asensor network

T-7 Min Chen | Investigating the Role of Vegetation and Soil Moisturein Land Surface Hydrology

T-8 Karl Vanderlinden | Soil Water Diffusivity Estimation fromDistributed Water Content Observations across a Rainfed OliveOrchard

T-9 Eleni Yeshaneh | Temporal Variation of Suspended SedimentTransport in the Koga Catchment, North Western Ethiopia andEnvironmental Implications

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T-10 Robert A. Root | Toxic metal(loid) speciation is controlled by ironmineral (bio)weathering in phytostabilized mine tailings

T-11 Yakov Pachepsky | Modeling Flow and Transport in Field Soil withPedotransfer and Scaling

T-12 Alexander M. Yakirevich | Augmentation of Monitoring NetworksUsing Information Theory and Ensemble Modeling withPedotransfer Functions

T-13 Elisabeth Bui | Net redistribution of Cs-137 provides evidence ofcontinental-scale interaction between hydrological andbiogeochemical processes

T-14 Ethan Kyzivat | Stable Water Isotope Analysis of Subsurface Flow inArtificial Hillslopes

T-15 Mark Seyfried | Reynolds Creek Carbon Critical Zone Observatory:Improving prediction of soil carbon storage and flux from thepedon to the landscape scale

T-16 Matthew C. Reid | Gas Exchange in the Wetland Rhizosphere:Quantifying Spatial and Temporal Variability at Field Scales withDissolved Gas Tracer Experiments

T-17 Xavier Zapata-Rios | PEDON SCALE SOIL MOISTURE ANDWATER FLUXES DYNAMICS DURING EXTREMELY DRY YEARSIN A HIGH ELEVATION SNOW DOMINATED LANDSCAPE

T-18 David Pal | Determining Relationships Between DissolvedHydrogen and Methane Porewater Concentrations and StaticChamber Flux Measurements in Vegetated Wetland Soils

T-19 Ryan D. Stewart | Improved understanding and prediction ofrunoff thresholds

T-20 Kenneth Wacha | Total Belowground Carbon Allocation inIntensely Managed Landscapes

T-21 Guo-Yue Niu | Analysis of an extreme rainfall-runoff event at theLandscape Evolution Observatory by means of a three-dimensionalphysically-based hydrologic model

T-22 Anouk Gevaert | Two-step soil saturation mechanism at hillslopescale

T-23 Carlotta Scudeler | Numerical simulations of isotope tracerexperiments at the Landscape Evolution Observatory

T-24 Steffen Klatt | Assessing water, carbon and nitrogen fluxes on thelandscape scale by coupling LandscapeDNDC, a regional multi-ecosystem biogeochemical model to the hydrological model CMF

T-25 Nicholas Cowan | A study of nitrous oxide (N2O) emissions on afield and farm scale

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T-26 Alex Furman | Exploring Root Uptake Under High FrequencyIrrigation Using Electrical Resistivity Tomography

T-27 Rebecca Lever | Quantifying pyrogenic carbon fluxes and meanresidence time in eroding hillslopes

T-28 John A. Trofymow | Developing a 100-year Retrospective CarbonBudget for the Sooke Watershed, Vancouver Island, BC

T-29 Joost L. Van Haren | CO2 sequestration through weathering ofbasalt tefra in the Landscape Evolution Observatory (LEO)

T-30 Tao Ma | Hydrochemical constituents of interflow compared fromartificial experimental monoliths and catchments

T-31 Iftekhar Ahmed | Bayesian Inference of Coupled Hydro-Biogeochemical Soil Organic Carbon Loss Model

T-32 Christopher J. Kelley | A decade of water and nitrate fluxes from adryland agricultural headwater catchment: Linking hydrologic andbiogeochemical drivers of the soil N cycle

T-33 Maria Knadel | Fusing Proximal Sensing Data for OptimalLocations of Soil Moisture Monitoring Stations

T-34 Christina M. Haberer | Oxygen transfer in the capillary fringe:Impact of physical heterogeneity and transient flow conditions

4:00 p.m. – 6:00 p.m. Soil Resource as a Primary Driver of Ecosystem Services -PosterLower Habitat Plaza

T-35 Hartmut Holländer | Impact of modellers’ decisions onhydrological a priori predictions

T-36 Sheng Ye | Derivation of Subsurface Stormflow Parameterizationfrom Regional Analysis of Streamflow Recession Curves: A PossibleClimate Dependence?

T-37 Adam Trueman | Vegetation as a spatiotemporally heterogeneouscontrol on landscape evolution: A critical zone approach toLandscape Evolution Modelling

T-38 Jason P. Field | Bridging from Soil to Ecosystem Goods and ServicesProvided by the Critical Zone

T-39 Samuel Prentice | QUANTIFYING HILLSOPE SOIL THICKNESSUSING FINE SCALE TERRAIN MODELLING

T-40 Carmen Burghelea | CONTRIBUTION OF ARBUSCULARMYCORRHIZA TO PLANT UPTAKE OF LITHOGENICNUTRIENTS IN AN ENCLOSED EXPERIMENTAL ECOSYSTEMAT BIOSPHERE 2

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T-41 Martha Gebhardt | Soil biotic indicators for improving native plantestablishment in disturbed Southwestern grasslands

T-42 Jinsung An | Chemical speciation of fluorine in solid materials bythe combined use of X-ray photoelectron spectroscopy andsequential extraction scheme

T-43 Junseok Lee | Total and soluble fluorine concentrations in soil afteroccurring hydrogen fluoride spill

T-44 Liu Yunjia | Arsenic Speciation in the Copper Tailings with theEffects of Magnetite Removal

T-45 Diane Hagmann | Effect of heavy metal contamination on selectedextracellular enzyme activities in soil

T-46 Karin A. Block | Interaction of Bacteriophage 6 withMontmorillonite and P. syringae Biofilm Aggregates

T-47 Adrianna Trusiak | Disassembly of Phage 6 by MontmorilloniteClay

T-48 Michael Young | Soil development, time, and ecosystem function inwater-limited systems

6:00 p.m. – 7:00 p.m. Dinner (Tuesday)

WEDNESDAY, 23 OCTOBER

7:30 a.m. – 8:30 a.m. Continental Breakfast (Wednesday)

Soil Resource as a Primary Driver of Ecosystem Services I -OralPresiding: Michael Young, Dani OrSahara Room

8:30 a.m. – 9:00 a.m. Hangsheng (Henry) Lin | New Frameworks for Decoding ComplexSoil Systems (Invited)

9:00 a.m. – 9:30 a.m. Dan O. Breecker | Soil carbonate accumulation: chemical,biological and physical controls (Invited)

9:30 a.m. – 9:45 a.m. Chelsea L. Arnold | Linking loss of water storage capacity in highelevation meadow soils to changes in soil structure and organicmatter stock after extreme drought

9:45 a.m. – 10:00 a.m. Craig Rasmussen | Using statistical methods to quantify andpredict catchment scale soil variability

10:00 a.m. – 10:30 a.m. Morning Break (Wednesday)

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Soil Resource as a Primary Driver of Ecosystem Services II- OralSahara Room

10:30 a.m. – 11:00 a.m. David Dunkerley | Water partitioning at the dryland soil surface:roles of precipitation intensity variation and plant-mediated waterfluxes (Invited)

11:00 a.m. – 11:15 a.m. Elmarie Kotzé | Influence of rangeland management practises onorganic matter contents and aggregation dynamics of clayey soils inthe semi-arid grassland biome, South Africa

11:15 a.m. – 11:30 a.m. Laura Turnbull | Mechanisms Regulating the Fate of Nitrogen inDrylands

11:30 a.m. – 11:45 a.m. Ann Tan | Topographic Influence on Spatial and Temporal Patternsof Grassland Productivity

12:00 p.m. – 1:30 p.m. Group Lunch (Wednesday)

1:30 p.m. – 3:30 p.m. Visit Landscape Evolution Observatory, Bioshere 2 or FreeTime

3:30 p.m. – 4:00 p.m. Afternoon Break (Wednesday)

4:00 p.m. – 6:00 p.m. Breakout Sessions (Wednesday)Sahara Room, B2 Café Patio, Gobi Room, High Rise Gallery, Casitas 1900 and 500

6:00 p.m. – 8:00 p.m. Conference Banquet

THURSDAY, 24 OCTOBER

7:30 a.m. – 9:00 a.m. Continentatal Breakfast (Thursday)

9:00 a.m. – 10:30 a.m. Group Reporting and Synthesis

10:30 a.m. – 11:00 a.m. Morning Break (Thursday)

11:00 a.m. – 12:30 p.m. Wrap-up in Plenum

12:30 p.m. – 1:30 p.m. Group Lunch (Thursday)

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Ahmed, IftekharBayesian Inference of Coupled Hydro-Biogeochemical Soil Organic Carbon Loss ModelAhmed, Iftekhar1; Karim, Abdullah1; Boutton, Thomas2;Strom, Kyle3; Fox, James4

1. Civil & Environmental Engineering, Prairie View A&MUniversity, Prairie View, TX, USA

2. Ecosystem Science and Management, Texas A&MUniversity, College Station, TX, USA

3. Civil & Environmental Engineering, University ofHouston, Houson, TX, USA

4. Civil Engineering, University of Kentucky, Lexington, KY,USA

The thematic focus of this USDA-CBG collaborativeapplied research is sustainable integrated monitoring of soilorganic carbon (SOC) loss from multi-use lands using state-of-the-art stable isotope science under uncertain hydrologicinfluences. In this study, SOC loss and water runoff arebeing monitored on a watershed scale using natural rainfallevents, and total organic carbon/nitrogen concentration(TOC/TN) and stable isotope ratio (13C, 15N)measurements with different land-use types on a southTexas urban watershed. This paper investigates the mid-project interdisciplinary research results to uncover practicalyet scientific ways to monitor SOC loss by (i) creation ofstatistical models to assess the relationship between rainfall-runoff and SOC release during soil erosion in space andtime, (ii) capturing the episodic nature of rainfall events andits role in the spatial distribution of SOC loss from erosion,(iii) stable isotope composition guided fingerprinting(source and quantity) of SOC by considering various types oferosion processes common in a heterogeneous watershed, tobe able to tell what percentage of SOC is lost from variousland-use types (Fox and Papanicolaou, 2008), (iv) creating anintegrated watershed scale statistical soil loss monitoringmodel driven by spatial and temporal correlation of flowand stable isotope composition (Ahmed et. al., 2013), and (v)creation of an integrated decision support system (DSS) forsustainable management of SOC under hydrologicuncertainty to assist the end users. References: Ahmed, I,Karim, A., Bouttom, T. W., Strom, K. B. (2013). MonitoringSoil Organic Carbon Loss from Erosion using StableIsotopes Proc., Soil Carbon Sequestration, May 26-29,Reykjavik, Iceland. Fox, J.F. and Papanicolaou, A.N. (2008).An un-mixing model to study watershed erosion processes.Advances in Water Resources, 31, 96-108.http://www.pvamu.edu/pages/4844.asp

An, JinsungChemical speciation of fluorine in solid materialsby the combined use of X-ray photoelectronspectroscopy and sequential extraction schemeAn, Jinsung1; Lee, Junseok1; Yoon, Hye-On1

1. Korea Basic Science Institute, Seoul, Republic of Korea

Chemical speciation of fluorine (F) in solid materialsshould be considered to assess its reliable risk to human andenvironment. However, studies related to F speciationscheme have not been extensively performed. In this respect,certified reference materials (CRM) with having highfluorine contents (i.e., slag (JK S9) = 17.3%, phosphate rock(Western 694) = 3.2%, Cupola dust (SX62-07) = 0.73%) andplant samples exposed to hydrofluoric acid are analyzed byX-ray photoelectron spectroscopy (XPS) to investigate thedifferent bond type of fluorine in various solid materials.Concurrently, the proportion of fluorine distributed in solidmaterials is also assessed by sequential chemical extraction(SCE) approach. The combined use of XPS and SCE enableus to assess the fluorine fractionation in various solidmaterials with different fluorine contamination sources.Acknowledgement This research was supported by a grantfrom the Korea Basic Science Institute (project No. E33300).

Appels, Willemijn M.The role of soil depth, bedrock permeability, andlateral flow on hillslope groundwater rechargepatternsAppels, Willemijn M.1; Graham, Chris B.2; McDonnell,Jeffrey J.1

1. Global Institute for Water Security, University ofSaskatchewan, Saskatoon, SK, Canada

2. Hetchy Hetchy Water and Power, Moccasin, CA, USA

The hillslope scale patterns of groundwater recharge arepoorly known. On hillslopes with a thin soil mantleoverlying bedrock, complex interactions of percolation ofwater through the soil, permeability contrasts between thesoil and the underlying bedrock and lateral redistribution ofwater result in large spatial variability of infiltration of waterinto the bedrock. Here, we combine new measurements anda new modeling approach to investigate how patterns of soildepth, bedrock topography, and bedrock permeability affectthose spatial patterns of groundwater recharge. We explorethe following questions: what are the effects of the spatialdistribution of soil depth and bedrock permeability ongroundwater recharge; what are the characteristics lengths ofwater delivery to, infiltration in, and lateral flow along thebedrock layer; how can we derive spatial distributions ofbedrock permeability without stripping away the soilmantle? We focus our work on the well-studied PanolaMountain experimental hillslope site where (sub)surface

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ABSTRACTSlisted by name of presenter

topography and soil depth distribution have been collectedpreviously. Here we report new measurements ofpermeability of the soil mantle immediately above thebedrock and within the bedrock itself to aid thedevelopment of a conceptual model to explore how therecharge pattern varies during different precipitation events.We found that the ratio between the rate of water deliveryand bedrock permeability controlled the effective fill rate ofthe depressions in the bedrock topography and the averageamount of recharge into the bedrock. By comparison, therun-on distance was mainly determined by the interactionbetween soil depth distribution and bedrock topography. Onthe Panola hillslope, the correlation length of the soil depthdistribution is larger than that of the bedrock permeabilitydistribution. As a result, the spatial pattern of bedrockpermeability was found to shorten run-on distances on thehillslope, most strongly for events with a low water deliveryrate.

Arnold, Chelsea L.Linking loss of water storage capacity in highelevation meadow soils to changes in soil structureand organic matter stock after extreme droughtArnold, Chelsea L.1; Berhe, Asmeret A.1; Ghezzehei, TeamratA.1

1. University of California, Merced, Merced, CA, USA

High elevation meadow soils provide essential ecosystemservices such as filtering, storing and slowly releasing waterin mountain watersheds. Extreme dry years can cause thewater table in these meadows to drop below historic levels.Drying induced changes in soil structure then follow as aresult of consolidation by capillary suction. Subsequently,consolidation leads to loss of macroporosity and waterholding capacity in these soils. Utilizing a modified triaxialsystem, we investigate the historic limit of dryness thatmeadow soils in the Central Sierra Nevada have experiencedin order to determine if the extreme dry summer of 2012irreversibly changed the structure of meadow soils. Wefurther relate the changes in soil structure and water holdingcapacity to measured changes in soil organic matter stockduring the same time period.

Bailey, Scott W.Influence of landscape position and transient watertable on soil development and carbon distributionin a steep, headwater catchmentBailey, Scott W.1; McGuire, Kevin4; Ross, Donald S.3; Bullen,Thomas2; Bourgault, Rebecca3; Gannon, John P.4

1. Northern Research Station, US Forest Service, NorthWoodstock, NH, USA

2. US Geological Survey, Menlo Park, CA, USA3. Department of Plant and Soil Science, University ofVermont, Burlington, VT, USA

4. Department of Forest Resources and EnvironmentalConservation, Virginia Tech, Blacksburg, VA, USA

Upland headwater catchments, such as those in theAppalachian Mountain region, are typified by coarse, well-drained soils, flashy hydrologic response, and low streambaseflow, suggesting minimal groundwater storage. Modelformulations of soil genesis, nutrient cycling, critical loadsand rainfall/runoff are typically based on verticalpercolation, soil horizons parallel to the land surface,mineral weathering inputs limited to the rooting zone anddrainage from lumped catchment reservoirs (e.g., thesubsoil) as the dominant source of stream flow. However,detailed study of the hydrologic reference catchment atHubbard Brook Experimental Forest, NH, USA showsstriking spatial patterns of soil development that reflect theinfluence of transient water tables within the solum innearly all landscape positions and transportation ofweathering products from deeper in the lithosphere to therooting zone. Shallow bedrock and variations in hydraulicconductivity promote lateral flow and development of atranslocational soil catena at the hillslope scale. Wedistinguished several soil groups based on presence ofdiagnostic horizons indicative of differing patterns ofpodzolization and carbon storage. Typical podzols werefound in well drained positions on steep back slopes andspurs and have limited exposure to groundwater in thesolum. E, Bhs, and Bh podzols, named for the dominantmineral horizon present, were formed by lateral, hillslopescale processes, each with a distinct frequency and depth ofwatertable development. Lateral podzols had up to 50%greater carbon content, and higher concentration of metalsassociated with spodic materials than typical podzols.Dissolved organic carbon concentrations in groundwatervaried from 13 mg/L in E-podzols to 1.5 mg/L in Bh-podzols. Spatial patterns in stream chemistry reflectdistribution of soils at the subcatchment scale. Modellingshows that precipitation events producing thresholdresponses in transient watertables in the different soilgroups has changed over the 50+ years of the HubbardBrook record, suggesting a mechanism that could alter thedistribution of soils and retention/release of carbon andother solutes over time.

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Hydropedologic catena at Hubbard Brook Experimental Forest.Dashed and solid arrows indicate portions of the catena where soilforming processes are controlled by vertical percolation and lateralgroundwater flow, respectively.

Bao, ZhongwenNumerical Analysis on the Factors Influencing theSoil/Atmosphere Diffusive Exchange of PersistentOrganic CompoundsBao, Zhongwen1; Beckingham, Barbara1; Maier, Uli2;Grathwohl, Peter1

1. University of Tübingen, Tübingen, Germany2. Helmholtz Centre for Environmental Research – UFZ,Leipzig, Germany

Abstract Soil/atmosphere exchange of persistent organiccompounds (POPs) acts as an important transport processinfluencing the environmental fate of POPs, especially whilesoils function as a second source via volatilization. Dry/wetdeposition from atmosphere to soil and re-volatilizationfrom soil to the atmosphere by diffusion are the majorprocesses. This study focuses on modeling of vapor phaseexchange of POPs across the soil/atmosphere interface usingthe numerical code MIN3P which was validated withanalytical solutions. Phenanthrene (Phe) as a representativeof hydrophobic legacy compounds was selected to elucidatethe relevant processes and parameters influencingsoil/atmosphere exchange. Time scales considered in themodel amount to 100 a of gas deposition and re-volatilization. Because of the high eddy diffusioncoefficients the atmospheric boundary layer is well-mixedand overall fluxes of Phe are limited by the soil side.Temperature variation is a key issue influencing thedynamical exchange of POPs in soil/atmosphere media.Sorption, seepage water flow rates, biodegradation and soilproperties (i.e. soil texture, water saturation) are decisive forthe concentration gradients which develop duringaccumulation and re-volatilization. Sorption causes strongretardation of re-volatilization and biodegradation. Duringthe deposition process of Phe, sorption limits the spreadingin short term while biodegradation functions in long termafter the top soil is fully loaded. Diffusion decides the re-volatilization of Phe due to the increase of temperature.Warming events, such as temperature increase from night todaytime, lead to a release of sorbed phase Phe, an increase ofpartial pressure. The model goes across the soil/atmosphereboundary and also allows to test sensitivity of the crosscompartment fluxes as a function of the dynamicconcentration gradients in atmospheric boundary layer

(ABL). The conceptual model of 1D soil/atmosphereexchange of Phe is shown in Fig. 1.

Fig. 1 : Conceptual model of soil/atmosphere exchange ofphenanthrene with regions identified

Baveye, PhilippeFate of terrestrial carbon: We need to start at themicroscopic scaleBaveye, Philippe1, 2; Otten, Wilfred2; Battaia, Guillaume3, 2;Falconer, Ruth2

1. Civil and Environmental Engineering, RPI, Troy, NY, USA2. SIMBIOS Centre, Abertay University, Dundee, UnitedKingdom

3. BioEMCo, AgroParisTech, Thiverval-Grignon, France

It is becoming increasingly recognized that soilmicrobial processes, and the effect of soil structure andwater retention on them, need to be described explicitly inany attempt to predict the fate of terrestrial carbon, and therelease of CO2 by soils. Current models of soil organicmatter dynamics divide soil organic matter into conceptualpools with distinct turnover times, assuming that acombination of biochemical and physical properties controldecay without explicit description. Albeit robust in theirapplication, such models are not capable to account forchanges in soil structure or microbial populations, oraccurately predict the effect of wetness or priming. A newclass of carbon fate models is needed, which explicitlyaccounts for microbial dynamics, physical processes and arespatially explicit to embrace the microscopic heterogeneity insoils. In the case of fungi, we demonstrate how such a modelcan provide contrasting results to existing approaches. Wepresent a model with spatially explicit representation ofmicrobial and Carbon dynamics, and physical structure toinvestigate how micro-scale processes manifest at the corescale with particular emphasis on evolution of CO2. Thefungal model is based upon previous work by Falconer et al.(2012) and includes the following processes: uptake,translocation, recycling, enzyme production, growth, spreadand respiration. The model is parameterised through acombination of literature data and parameter estimation(Cazelles et al., 2012).The Carbon model comprises twopools, particulate organic matter which through enzyme

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activity is converted into dissolved organic matter. Thefungal and carbon dynamics occur within a 3D soil structureobtained by X-ray CT. In addition Lattice Boltzmannmodelling is used to predict the water distribution withinsoil structures. Results show that CO2 is affected not only bythe amount of Carbon in the soil but also by microbialdynamics, soil structure and the spatial distribution of OM.The same amount of OM can result in substantially differentrespiration rates, with surprisingly more released CO2associated with increased clustering of OM. With increasingsoil C content, respiration increases non-linearly, and morerapidly so above a critical threshold. This type of model is ofgreat benefit towards understanding underground ecology,offering a predictive framework and stimulating hypothesis-driven experimentation. We demonstrate the novel insightsthat this approach can offer for C dynamics. We discuss thebenefits and the challenges that need to be overcome beforethis class of model can be incorporated in large-scale carbon-climate models. References, Cazelles, K., W. Otten, P.C.Baveye, and R.E. Falconer. 2012. Soil fungal dynamics:Parameterization and sensitivity analysis of modelledphysiological processes, soil architecture and carbondistribution. Ecological Modelling 248, 165-173. Falconer, R.E., A. Houston, W. Otten, and P. Baveye. 2012. Emergentbehaviour of fungal dynamics: influence of soil architectureand moisture distribution. Soil Science 177 (2), 111-119.

Berhe, Asmeret A.Erosion of soil carbon and nitrogen in low-ordercatchments in the Sierra NevadaBerhe, Asmeret A.1; Stacy, Erin1; Hart, Stephen C.1;McCorkle, Emma1; Hunsaker, Carolyn2; Johnson, Dale3

1. University of California, Merced, Atwater, CA, USA2. US Forest Service, PSW, Fresno, CA, USA3. University of Nevada, Reno, Reno, NV, USA

Erosion in the Sierra Nevada Mountains transportstopsoil, and associated carbon and nitrogen, imposingsignificant controls on dynamics of soil organic matter(SOM) in the eroding watershed. Recently, the implicationsof lateral distribution of sediment on carbon (C) andnitrogen (N) dynamics in eroding upland forestedecosystems have been receiving growing recognition. Theamount and nature of the eroded C and N exported fromeroding watersheds depends on the amount and stability ofthese essential elements in eroding slope profiles, the typeand rate of erosion, and anthropogenic disturbances.Sediment traps located at the point where first-orderstreams leave the watershed provide insight into the amountand composition of material removed by soil erosion. Here,we will present data on the amount and composition of soilmaterial eroded from eight first-order watersheds in themixed-conifer zone of the Sierra National Forest in the KingsRiver Experimental Watershed. Our results show that thereis large variability in nature of exported material across eightheadwater catchments that is not directly related towatershed size or climatic variability.

Block, Karin A.Interaction of Bacteriophage 6 withMontmorillonite and P. syringae BiofilmAggregatesBlock, Karin A.1; Hawkins, Holly1; Trusiak, Adrianna1; Katz,Al2; Gottlieb, Paul3; Alimova, Alexandra3; Steiner, Jeffrey C.1

1. Earth and Atmospheric Sciences, City College of NewYork, New York, NY, USA

2. Physics, City College of New York, New York, NY, USA3. Sophie Davis School of Biomedical Education, CityCollege of New York, New York, NY, USA

Viruses are important components of soils that controlmicroorganism populations and serve as delivery vehicles forgenetic material through transduction. Viruses are known toaggregate with clays, often resulting in virus inactivation. Asa result, the interaction between soil minerals, viruses andthe microbiome has profound implications inbiogeochemical cycling and the health of plants andanimals. Bacteriophage 6 is a member of the Cystoviridaefamily of viruses, the only family of lipid enveloped phage.The 6 host cell is Pseudomonas syringae, a common plantpathogen. Prior work has shown that montmorillonite andP. syringae heteroaggregate and that biofilms form withinthree hours of mixing the bacteria with montmorillonite.The role of montmorillonite in mediating the infection of P.syringae by 6 is explored by monitoring the survivability ofP. syringae after the addition of 6 to suspensions ofmontmorillonite platelets and P. syringae at different timepoints. It is observed that when 6 is added to themontmorillonite suspension prior to addition of P. syringae,the 6 phage is inactivated and biofilm growth iscomparable to growth without phage. However, when the 6is added to the montmorillonite suspension after theformation of biofilms (t = 4 h), the 6 retains its infectivityof P. syringae. While the inactivation of 6 bymontmorillonite is a result of electrostatic and/or van derWaals interactions between the platelets and phage, inbiofilm - montmorillonite heteroaggregates, the biofilmlikely limits physical contact between the montmorilloniteplatelets and virions and thus prevents loss of 6 infectivity.

Bloeschl, GuenterFrom the local to the catchment scale: challengesand ways forward (Invited)Bloeschl, Guenter1

1. Hydraulic Water R Engineering, Vienna University ofTechnolog, Vienna, Austria

While the mechanistic, upward modelling approachallows to portray hydrological processes in much detail,coupling these processes across many magnitudes of spaceand time scales remains a challenge. One way of sheddinglight on the process interactions across scales is thecomparative hydrology approach which aims at learningfrom the similarities and differences between catchments indifferent places, and interpreting these in terms of the

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underlying climate and landscape controls. Thispresentation will illustrate the comparative hydrologyapproach by a number of examples of hydrologic response inAustria. The time scales considered range from hours tomillennia. In a region in southern Austria, for example, thegeology consists of phyllites that are deeply weathered andhave led to deep soils and therefore deep flow paths. Acomplex landscape has evolved with tortuous flow pathsboth on the hillslopes and in the valleys which in turn retardrunoff response and impedes the evolution of an efficientdrainage network. In contrast, in a region in Eastern Austriathe geology consists of marl and clay which has led toshallower soils and faster flow paths. As a result of frequentconvective events in the region and the flashy soilcharacteristics, the catchment form has adapted to theflashy response and produced an efficient drainage networkwhich in turn enhances the flashiness of the hydrologicresponse. These are examples of the co-evolution oflandform and hydrological processes. These findings areused as the basis for assessing current modelling conceptsacross space and time scales. Emerging space-time patternsare discussed and how they could be used to assist inhydrological modelling, in particular, to give guidance onsuitable model structures and parameter patterns. The roleof comparative hydrology in identifying feedbacks andinteractions that would be difficult to obtain from pointmeasurements alone is discussed as are advances inmeasurement strategies across scales.

Boot, Claudia M.Linking Lability and Composition of DissolvedOrganic Matter Across the Terrestrial-AquaticInterface (Invited)Boot, Claudia M.1; Hall, Ed K.1, 2

1. NREL, Colorado State University, Fort Collins, CO, USA2. Fort Collins Science Center, United States GeologicalSurvey, Fort Collins, CO, USA

Terrigenous DOM moves from terrestrial to aquatichabits where it fuels secondary production in a wide range ofaquatic habitats. However, at any one time, only a fraction ofthe DOM pool is accessible to microbes (i.e. labile) and theproportion of labile to recalcitrant DOM varies with abioticfactors including temperature, moisture and nutrientcontent. In this context, global change, including shifts inseasonality and reactive N inputs, has the potential to alterDOM composition and its associated flux andtransformation. To assess the effects of season and reactiveN inputs on DOM properties we studied a long-term (15years) fertilization experiment in old growth sub-alpineforest in, Rocky Mountain National Park. We sought todetermine how season and reactive N inputs influenced soilDOM composition and lability in ambient and N fertilizedplots. Surface soil samples were collected in July andSeptember, 2012, DOM was extracted and characterized bywith a mass spectrometry (MS) based meta-metabolomicsapproach. Soil extracts were incubated with natural lakebacterial communities and respiration was monitored. Using

ultra performance liquid chromatography (UPLC) coupledwith MS we measured approximately 3200 features in thesoil DOM pool. Principle components analysis indicatedseason is a stronger driver of DOM composition thanfertilization, with PC1 describing 61% of the variabilitybetween July and September 2012. Soil DOM from July andSeptember, fertilized and ambient treatments, was incubatedwith bacterial communities from the adjacent body of water,Loch Vale, to understand how the compositional differencesrelate their decomposition properties. With this effort tounderstand the relationship between DOM composition andlability, and how the relationship is influenced by seasonand N fertilization, we can begin to understand the effectsglobal change factors on C and N dynamics in a sub-alpineecosystem. These findings can then be used to inform globalbiogeochemical models, and generate hypothesis to test foruniversal mechanisms in other ecosystems.

Breecker, Dan O.Soil carbonate accumulation: chemical, biologicaland physical controls (Invited)Breecker, Dan O.1

1. Geological Sciences, University of Texas at Austin, Austin,TX, USA

Pedogenic calcium carbonate (CaCO3) occurs in soils onnearly half of Earth’s land surface. Its accumulation isimportant for understanding Earth’s carbon cycle, theweathering of silicate minerals, the hydrology of drylandsoils, soil phosphorous budgets, desertification andpaleoenvironmental reconstruction. I discuss recentprogress, current challenges and some ideas about advancingthe quantification of soil CaCO3 accumulation. Recent workbased on stable isotope compositions of soil CaCO3collectively suggests that accumulation occurs duringdroughts, typically when the soil is hot and dry. In contrast,simulations using HYDRUS 1D with UNSATCHEM predictsoil CaCO3 accumulation under wetter conditions whenplants are growing. A current challenge is to resolve thisdiscrepancy, which suggests some process might be missingfrom the model. Indeed, the model maintainsthermodynamic equilibrium whereas dryland vadose andgroundwaters are typically supersaturated with respect tocalcite. Furthermore, organic matter coatings are known toinhibit calcite precipitation, a process not considered by themodel although it has been suggested to explain theobserved supersaturation of dryland waters. I suggest thatgiven the abundance of organic matter in soils, suchcoatings likely inhibit CaCO3 precipitation until droughtconditions drive sufficient supersaturation. The idea thatorganic matter inhibits CaCO3 accumulation leads me topropose a new conceptual model for soil carbon. The modelinvolves a delicate balance between organic and inorganiccarbon in which accumulation of one favors decumulationof the other. Organic matter poisons calcite nucleation sitesand lowers pH, which inhibits calcite accumulation andfavors dissolution. Simultaneously, the presence of solidCaCO3 increases pH, which stabilizes extracelluar oxidative

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enzymes (OE) and thereby results in efficient decompositionof organic matter. I suggest that this competition occursvertically within soils, horizontally across landscapes andclimatic zones and through time with changes in climate,land use and vegetation. If this model is accurate, then thedynamics of inorganic and organic carbon in soils are bestinvestigated together. This will require an interdisciplinaryeffort involving vadose zone hydrologists, organic andinorganic geochemists, microbiologists and pedologists. Forexample, examination of pedogenic CaCO3 surfaces with X-ray photoelectron spectroscopy might indicate theimportance, or lack thereof, of organic matter coatings.Studying spatial gradients in microbial communitycomposition and OE activities would also help test theproposed conceptual model. Amending soil physics modelsto accommodate pedogenically-driven changes in porosityand hydraulic conductivity would advance soil carbonmodeling. Comparing simulated with measuredtemperatures of soil CaCO3 formation would help validateand improve numerical calcic soil models. Couplingnumerical models of organic and inorganic carbon mightpave the way for accurately simulating past and futurechanges in soil carbon over much of Earth’s land surface. Achallenge remains finding the appropriate natural soils andchrono- and climosequences with which to compare modeloutput. Experimental pedology should be considered as oneway forward.

Breshears, David D.Beyond the Big-leaf Homogeneity Assumption inEvapotranspiration Partitioning: Factoring inCanopy Cover HeterogeneityBreshears, David D.1; Villegas, Juan C.2; Espleeta, Javier E.3;Morrison, Clayton T.1; Huxman, Travis E.4

1. Univ Arizona, Tucson, AZ, USA2. Univ de Antioquia, Medellin, Colombia3. Univ of Washington, Seatle, WA, USA4. Univ of California - Irvine, Irvine, CA, USA

Whereas quantifying evapotranspiration (ET) was afundamental environmental advance of the past century,partitioning evapotranspiration into the componentprocesses of soil evaporation (E) and plant transpiration (T)is currently required to improve mechanistic understandingof ecohydrological controls over plant productivity,biogeochemical cycling and climate feedbacks. Existingtheory for unpartitioned ET, developed for homogeneousvegetation cover, uses spatial aggregation of vegetation (e.g.,via Leaf Area Index—LAI) into a homogeneous “big-leaf”.However, in many ecosystems, there is substantialheterogeneity between patches with plants that generate T,and interplant spaces that often generate most E. Given themajority of terrestrial systems are highly heterogeneous, ETpartitioning needs alternatives to homogeneity assumptionto overcome potentially incorrect estimations of surface-atmosphere exchange. To initiate conceptual discussion, herewe hypothesize a framework relating patterns of canopycover to their influence on ET partitioning via vegetation

effects on main E and T drivers. More specifically, wehypothesize that, when holding LAI constant, at low levels ofcover increases in canopy cover result in disproportionatelyhigh increases in T relative to changes in E, and at highercover disproportionately low increases in T relative tochanges in E occur due to canopy self-shading. Additionally,changes in LAI and other ecosystem characteristics areexpected to either amplify or mute the extent of theseeffects, but are not expected to modify their direction.Collectively, the effects of canopy cover on E and T result ona net effect on either E or T, such that the net partitioning isdetermined by a combination of canopy cover, canopyarchitecture, soil water status, and climate. Thishypothesized conceptual framework for ET partitioning isconsistent with the very limited relevant published data, andsuggest that the framework may be applicable acrossdifferent vegetation types. Overall, our conceptual modelhighlights that combining canopy cover with previouslyconsidered variables into the fundamental approach for ETpartitioning is a concept that, while yet not quantitativelydeveloped, merits further discussion and consideration.

Buckeridge, Kate M.Spring thaw vegetation leachate does not stimulatesoil microbial activity in Arctic thermokarst soilsBuckeridge, Kate M.1, 4; Schaeffer, Sean2, 4; Baron, Andres3;Mack, Michelle3; Schuur, Ted3; Schimel, Joshua4

1. University of Kansas, Lawrence, KS, USA2. University of Tennessee, Knoxville, TN, USA3. University of Florida, Gainsville, FL, USA4. University of California, Santa Barbara, CA, USA

Vegetation leachate is an important stimulant tomicrobial activity in aquatic systems, but it is not knownhow this leachate impacts soil microbial activity. Weinvestigated leachate impacts at thaw in a disturbed,nutrient-limited arctic landscape. When upland permafrostthaws, thermokarst (land subsidence as a result of thawing)results in large slope collapse and landscape erosion; suchevents are increasing with a warming climate. Thermokarstscars are common in the Arctic, allowing us to analyze achronosequence of ecosystem recovery since disturbance (5,25, 54 and 150 y). Despite the low nutrient availability inundisturbed arctic tundra, intermediate ecosystem recovery(54 y) is characterized by strongly enhanced above-groundbiomass (shrubbiness); the nutrient source for this biomassis unknown. We hypothesized that nutrient inputs fromupslope vegetation leachate during the annual spring thaw,combined with differential microbial stimulation betweenrecovery stages could be a potential mechanism contributingto this enhanced aboveground biomass. In winter, wesampled frozen soil cores (n=5) from the surface horizon ofeach of the 4 recovery stages of the thermokarstchronosequence and from undisturbed tundra directly abovethe thermokarst scar. In addition, we collected live(dormant) plants and surface litter from the snow-coveredundisturbed tundra, with which we made water-extracted (0-2 oC) vegetation leachate. To test the response of soil

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microbes to thaw pulses of vegetation leachate, we addedthis leachate (or water) to the frozen soil cores, and steppedthem up in temperature from -10 oC to +2 oC over thecourse of 6 days. During the course of the incubation wemeasured soil respiration as an indicator of microbialactivity. At the end of the incubation we measured changesin microbial biomass and extractable soil C, N and P and soilgross N mineralization. We calculated expected recovery ofthe leachate C, N and P addition in the microbial and soilpool. Leachate addition had surprisingly little effect onmicrobial activity, and was much less important than timesince thermokarst disturbance for microbial activity and soilnutrient status over thaw. Microbial activity and biomassnutrient contents were highest in the shrubby, intermediaterecovery stages. Most of the P in the vegetation leachate wasrecovered in the microbial biomass, in the older thermokarstsoils (i.e. 150 y), indicating these soil microbes were stronglyP-limited at thaw. There were no other significant impacts ofleachate on microbial activity, microbial C or N, or soil C, Nor P pools. Although the leachate provided a substantialinput of C, N and P, we suspect leachate quality was poor, assupported by the very low proportion of C added that wasrespired in the samples with leachate alone. Despite the verylarge effect that vegetation leachate has on aquatic processes,in this study it provided much less of an impact on soilprocesses, regardless of the age of the landscape.

Bui, ElisabethNet redistribution of Cs-137 provides evidence ofcontinental-scale interaction between hydrologicaland biogeochemical processesBui, Elisabeth1; Chappell, Adrian1

1. CSIRO Land and Water, Canberra, ACT, Australia

Soil redistribution at the Earth surface is a keygeomorphological process that is the result of interactionsbetween soil, land, and atmospheric processes. It is mostreliably traced by cesium-137 (137Cs) and inventories havebeen used around the world to estimate net (ca. 30-40 year)soil redistribution by wind, water and tillage, typically at thelocal scale, since the late 1970s. Recently 137Cs was used toestimate net soil redistribution at the catchment scale forthe continent of Australia. Here we use that mapping toprovide new insights into the interaction of fluvial andeolian processes over Australia. The Lake Eyre Basin (LEB) incentral Australia is at the heart of these interactions. Fluvialprocesses move eroded soil and sediment down toward LakeEyre, the lowest point in Australia. Large-scale fluvial activityin the LEB is triggered by La Nina events. During El Ninoyears, dust-raising wind systems redistribute this sedimentfrom the lake and fluvial beds in the LEB across Australiawhere it accumulates behind distant forests that act as windbreaks. Soil nutrients in the deposited dust fertilize theseforests. Carbon in sediment can be a source of atmosphericCO2 if it decomposes during its journey through the aquaticcontinuum or in the atmosphere, before it enters the marineenvironment and becomes a sink of atmospheric CO2. Thisscale of mapping and large area assessment provides new

insights into contemporary geomorphological andbiogeochemical processes which can inform current naturalresources management issues such as erosion, land usechange, and conservation of biodiversity. Erosion of topsoilis not as dire an environmental problem as many suggest.Severe erosion is limited to cropped areas and respondsrapidly to soil conservation measures. However, it is clearthat agricultural practices need to be carefully managed tominimize erosion loss, especially on highly erodible soils.Extensive areas of contemporary eolian deposition exist thatcorrespond to unique bioregions, characterised by broad,landscape-scale natural features and environmentalprocesses that influence the functions of entire ecosystems.Policy making for biological conservation in Australia todate has not taken account of large-scale spatialbiogeochemical cycling patterns and thus is overlooking keyprocesses in the maintenance of healthy functioningecosystems and biodiversity on this unique dry continent.

Burghelea, CarmenCONTRIBUTION OF ARBUSCULARMYCORRHIZA TO PLANT UPTAKE OFLITHOGENIC NUTRIENTS IN AN ENCLOSEDEXPERIMENTAL ECOSYSTEM AT BIOSPHERE 2Burghelea, Carmen1; Zaharescu, Dragos1; Dontsova,Katerina1; Maier, Raina1; Chorover, Jon1; Huxman, Travis2

1. Biosphere 2, University of Arizona, Tucson, AZ, USA2. University of California, Irvine, CA, USA

Mycorrhizal fungi are microscopic soil organisms livingin symbiosis with plant roots; they are capable of regulatingresource allocation between abiotic and biotic componentsin soil/rock-plant systems. They are key players in manyecosystem functions, including nutrient cycling andformation of soil structure. The most common rootassociated mycorrhizae are the ectomycorrhiza and vesiculararbuscular mycorrhiza (VAM). While ectomycorrhiza hasbeen shown to enhance weathering and bio-uptake ofnutrients by actively secreting low molecular organiccompounds, the mechanisms of mineral driven weatheringby vesicular arbuscular mycorrhiza (VAM) are poorlyunderstood. The present study addresses the role of VAM inlithogenic element uptake by plants growing on nutrientlimited mineral substrate. Specifically, we compared thebiological uptake of a number of nutrients (P, K, Ca, Mg, Si,Na, Fe, Mn, Cu, Zn, B, Mo, Ni, Co and Al) and trace elements(Ti, V, Se, Sr, Ba, Be, Cr, As, Ag, Cd, Sn, Sb, Tl, Pb) by buffalograss (Buchloe dactyloides), a perrenial western NorthAmerican grass. Plants were grown in column experimentson different rock media for 4 months, after which they weresacrificed. The columns contained two types of volcanicrock, basalt and rhyolite, and two types of biologicaltreatment, plants inoculated and uninoculated with VAM(Glomus intraradices). To detect changes in plants uptake oflithogenic elements, the aboveground and belowgroundbiomass was acid digested and analyzed for elementconcentrations by ICP-MS. We compared the total uptake ofelements by biomass of plants infected and non-infected

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with mycorrhiza for each type of rock. Root-shootpartitioning of elements was also evaluated. The results ofthis mesocosm experiment showed that buffalo grass wasable to grow in the rock without addition of a fertilizer,deriving necessary nutrients from dissolution of theminerals in the rock. Nutrient and trace element uptake bythe grass was enhanced when plants were infected with VAM.Differences between mycorrhizal and non-mycorrhizaltreatments were significant for both basalt and rhyolite, butelements that had increased uptake differed between therocks reflecting their mineralogy and elemental composition(Fig 1A & B). Roots accumulated significantly largeramounts of lithogenic elements than the shoots of plantsand differences between biomass removal of the elementsamong VAM and non-VAM treatments were greater for theroot uptake. Results of this study indicate that VAM helpsgrasses grown in nutrient deficient conditions accessnutrients needed to satisfy their physiological requirements.

Fig. 1 Comparison of total uptake of lithogenic elements by plantsinfected with mycorrhiza (+VAM) and non-infected (-VAM) showingsignificant differences in element uptake by plant roots on basalt (A)and rhyolite (B).

Campbell, Colin S.Effects of changing rainfall patterns on soilmoisture storage and plant canopy dynamics in asubalpine meadowCampbell, Colin S.1; Gill, Richard A.2; Campbell, Gaylon S.1;Cobos, Douglas R.1; Dixion, Seth S.1

1. Research and Development, Decagon Devices, Pullman,WA, USA

2. Dept. of Biology, Brigham Young University, Provo, WA,USA

Soil moisture has been shown to be a critical controllingfactor determining net primary productivity (NPP) of water-limited ecosystems. Changing climatic conditions in thewestern United States are predicted to change the frequencyand duration of rainfall, thus altering soil moisture storesand dependent plant community longevity and diversity.The object of this study was to investigate the role of soil indetermining the effects of these changing rainfall patterns insubalpine ecosystems on the Wasatch Plateau, UT, USA. Aseries of long-term replicated sites were established tocontrol precipitation intensity and frequency in historicallygrazed and ungrazed areas, and monitor soil moisture andplant productivity. Results showed extreme rainfall eventsincreased the duration of soil water potential above wiltingpoint, especially in the ungrazed sites, compared to thecontrol. Limiting soil water availability through frequent butdiminished rainfall had little or no effect on biomass

accumulation early in the season, but considerable effects inthe late season due to decreasing soil water availability.

Chen, MinInvestigating the Role of Vegetation and SoilMoisture in Land Surface HydrologyChen, Min1, 2; Willgoose, Garry1; Saco, Patricia1

1. Discipline of Civil, Surveying and EnvironmentalEngineering, The University of Newcastle, Callaghan,NSW, Australia

2. Department of Hydrology and Water Resources, ChinaThree Gorges Unveristy, Yichang, China

Soil moisture is an important variable in the climatesystem, and is intrinsically linked with the climate andvegetation. Both soil properties and vegetation exert greatinfluence on the land surface hydrological cycle viainfiltration and transpiration. In this study, we analyzed athree-year (2005-2007) dataset of daily soil moisture at theStanley semi-arid catchment in the southeastern Australia,using two different land surface models (LSMs), i.e. a soilmoisture model (HYDRUS) and a bio-hydrological model(IBIS). In the first set of the analyses, the choice between aconstant leaf area index (LAI) and a temporally varying LAIfor predicting daily soil moisture dynamics was investigated.Calibration results from both models consistently suggestedthat a constant LAI, rather than a full seasonal cycle ofvegetation dynamics, was sufficient to reproduce daily soilmoisture at our site. We did, however, find that soilparameters were changed if the LAI seasonality was input.Those soil parameter sets that were most sensitive to thelong-term mean LAI were the most sensitive to the seasonalcycle. Moreover, we found a strong correlation betweenantecedent rainfall measurements and remote sensingvegetation data, which suggested a simple and effective wayto obtain LAI values (either a long-term average of a fullseasonal cycle) via regression rather than physical modellingof LAI. In the second set of the analyses, the two LSMs wereevaluated and compared using the Monte-Carlo GLUEmethod. The IBIS soil moisture calibration was better for thesurface 30 cm, because its soil component is moreappropriate for the surface condition. The HYDRUScalibration was superior for the full 90 cm profile, due to abetter fitting vegetation component. Both models performedsatisfactorily under average semi-arid hydroclimaticconditions, while model deficiencies only became significantwhen simulating the soil moisture response to extremeprecipitation events. Better calibration of soil moistureresulted in less uncertainty in the three-year total waterpartitioning among the hydrologic variables modelled(surface runoff, evapotranspiration and deep drainage). Thiswas consistent for both surface and full profile. For thesurface, the total evapotranspiration, and total surfacerunoff plus deep drainage for the best-performing soilmoisture simulations were quite consistent between IBIS andHYDRUS. Though the combined total of the surface runoffand deep drainage was well identified (due to the soil waterbalance constraint), the partitioning between surface runoff

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and deep drainage was less well identified. The studyindicated that LSMs may be able to accurately predicthydrology if soil moisture is accurately estimated.

Cory, Rose M.Going to the dark side: a novel pathway for abioticoxidation of dissolved organic matter in arctic soilwaters (Invited)Cory, Rose M.1; Page, Sarah E.2; Sander, Michael2; Kling,George W.3; McNeill, Kristopher2

1. Earth & Environmental Sciences, University of Michigan,Ann Arbor, MI, USA

2. Institute of Biogeochemistry and Pollutant Dynamics,Swiss Federal Institute of Technology Zurich, ETH,Zurich, Switzerland

3. Department of Ecology and Evolutionary Biology,University of Michigan, Ann Arbor, MI, USA

Hydroxyl radical (•OH) is a reactive oxidant of dissolvedorganic matter (DOM) in aquatic environments. Thecurrently accepted view is that •OH is important for DOMcycling only in sunlit environments in which •OH isphotochemically formed, but new work suggests that •OHmay be a formed in the dark via abiotic oxidation of reducedDOM or ferrous iron, Fe(II). These findings suggest thatdark •OH formation may be important in soil C dynamicswhere reduced DOM and Fe(II) are produced by anaerobicmicrobial respiration. We investigated this novel pathway ofdark •OH formation in soil waters of the Alaskan Arcticacross a vegetation toposequence representing the dominantlow–arctic landscapes of hilltop heath to mid–slope tussocktundra to lowland wet sedge. More reduced, iron and DOM–rich soils had the highest •OH formation, consistent withthe proposed model of dark •OH formation from theoxidation of ferrous iron and reduced DOM by oxygen. Wefound that the formation of •OH from these samples isrelated to the reduction of oxygen by both reduced iron andDOM. At landscape scales, abiotic oxidation of organicmatter by •OH in soils may be at least as important tocarbon cycling as is bacterial respiration of DOM in surfacewaters. The controls on this •OH oxidation are linked to thecycle of reducing and oxidizing soil conditions, which inturn are governed by hydrological residence time andflushing.

Dark formation of hydroxyl radical from reduced dissolved organicmatter and iron. Reduced dissolved organic matter (DOM) andferrous iron are produced during anaerobic microbial respirationand are stable under anoxic conditions. When these reduced speciescome into contact with O2, the reduced DOM and ferrous iron willreduce O2 by three electrons to form •OH. The •OH formed isexpected to irreversibly oxidize DOM, forming CO2 and lowmolecular weight, bio–available products in the process. After thereduced DOM and iron are oxidized by oxygen, they may again bereduced if anaerobic conditions are re–established.

Cowan, NicholasA study of nitrous oxide (N2O) emissions on a fieldand farm scaleCowan, Nicholas1, 2; Famulari, Daniela2; Skiba, Ute2

1. Geosciences, University of Edinburgh, West Lothian,United Kingdom

2. Land/atmosphere exchange, Centre of Ecology andHydrology, Edinburgh, United Kingdom

Of the 3 dominant GHGs (CO2, CH4 and N2O) theestimated anthropogenic fluxes of N2O have the largestuncertainty associated with them. Agricultural activities arebelieved to be the largest source of global anthropogenicN2O with emissions forecast to rise due to an increase inlivestock numbers and the growing use of artificialfertilisers. Many individual agricultural sources of N2O arepoorly defined with very large associated uncertainties. Alack of understanding of these emissions prevents accurateestimates of N2O fluxes to be made on a large scale. The aimof this study is to use modern measurement methodology toimprove understanding of N2O fluxes from many differentagricultural sources on the field and farm scale. This workwill add to the increasing number of studies whichcontribute to the improvement of the IPCC guidelines forcalculating N2O emission factors from which national andglobal N2O inventories are calculated. Using high accuracychamber methods and eddy covariance, individual sources ofN2O are measured and monitored regularly over the periodof a year. The flux measurements made are cross validatedamongst different methods and across different scales. Fieldand landscape (farm) scale measurements are carried outand then results will feed into a simulation model of carbonand nitrogen biogeochemistry in agro-ecosystems such asDNDC and DAYCENT. This will provide an N2O budget onthe landscape scale, that can then be used for upscaling theresults to the national level by using regional scale models.The compilation of the dataset describing the landscape

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involves measuring fluxes from arable and grazed fields on aregular basis as well as other known sources of N2O such asmanure heaps and drainage streams from agricultural land.Flux measurements from soils are accompanied bymeasurements of soil ammonium and nitrateconcentrations, pH, soil moisture content, total carbon andnitrogen content and combined with detailed meteorologicaland farm management data. Once gathered, themeasurements will be used to complete a farm scale N2Oinventory of a working livestock farm at Easter Bush Farmestate. Easter Bush farm estate is a working livestock farmowned and run by the Scottish Agricultural College. Thefarm estate covers 1,013 hectares (2,500 acres) of land inlowland Scotland. The farm contains over 200 cattle, 1400sheep and has capacity for 120 pigs. 80 hectares of land willbe monitored frequently for N2O emissions at the farmestate. This land will consist of a number of arable fields(mostly barley) and fields grazed by sheep and cattle. Theactivities at the farm are closely recorded by the farmmanagement to provide a detailed account of fertiliser useand land management. The project focusses on measuringmany known sources of N2O whilst also searching for newsources to define. The management of the farm will bemonitored and all data will be used to create N2O emissionfactor estimates through a variety of simple and complexmodels. Results obtained from models will be comparedwith measurement data for verification.

Davies, JessicaModelling Nutrient Transformations Through TheCritical Zone: From Atmosphere To Plants, Soils ToStream At The Regional ScaleDavies, Jessica1, 2; Quinton, John N.1; Tipping, Ed2

1. Lancaster University, Lancaster, United Kingdom2. Centre for Ecology and Hydrology, Lancaster, UnitedKingdom

The interactions between biogeochemical andhydrological processes are highly coupled and intertwinedwith the physical properties of the soil. Hence, if we are tounderstand and quantify the stores and fluxes of nutrientswithin the critical zone it essential that an integratedapproach to modelling is taken. Within the Long-TermLarge-Scale (LTLS) project, development of an integratedmodel is underway which will simulate the pools and fluxesof carbon, nitrogen and phosphorus (C, N, and P) betweenatmospheric, vegetation, soil and aquatic systems for thewhole of the United Kingdom for a period spanning fromthe onset of the industrial revolution up until the presentday. Throughout this time span, humans have transformedthe nutrients in our landscape through industrialization,agricultural intensification and urbanization. It is importantto consider all compartments of the critical zonesimultaneously in order to trace the effects of deposition,fertilization, cultivation and land use change. It is alsocrucial that C, N and P are considered concurrently, as theirintegration controls the generation of biomass andconsequent production of soil organic matter –

consideration of C (or indeed C + N) alone in attempting tounderstand ecosystem function is insufficient as N and P arethe most commonly limiting elements. The LTLS integratedmodel incorporates enhanced versions of the N14C [1] andRothC [2] models (simulating terrestrial biogeochemicalcycling in semi-natural and agricultural land areasrespectively), with hydrology derived from the Grid-to-Grid[3] model. The flux of sediments from terrestrial tofreshwater compartments is driven by the hydrology, land-use and biogeochemical subsystems and subsequent riverineprocesses are also simulated. Here, the task of linkingterrestrial biogeochemical cycling in semi-natural land typeswith soil erosion processes at regional spatial scales andmonthly to centennial temporal scales is focused on. Amethodology for integrating these processes is presentedand issues in doing so discussed. Preliminary results in thisendeavor are presented. [1] Tipping, E. et al., 2012 EcologicalModelling, 247. 11-26. [2] Jenkinson, D. S. and Coleman, K.,2008. European Journal of Soil Science, 59: 400–413. [3] Bell,V.A. et al, Journal of Hydrology, Volume 377, Issues 3–4, 30October 2009, Pages 335-350.

Driscoll, Jessica M.Role of storage on hydrologic and chemical flux insoil-limited alpine catchments in the SouthwesternUSADriscoll, Jessica M.1; Meixner, Thomas1; Steven, Jepsen2;Molotch, Noah2; Williams, Mark W.2; Sickman, James O.3

1. Hydrology and Water Resources, University of Arizona,Tucson, AZ, USA

2. INSTAAR, Colorado Univeristy, Boulder, CO, USA3. Environmental Science, University of California atRiverside, Riverside, CA, USA

Montane regions of the water resource-limited WesternUnited States receive the majority of their annualprecipitation in winter and early spring as snow (Serreze etal., 1999). This hydrologic input is physically and chemicallybuffered through hydrologic connectivity at the catchmentscale (Laurenson, 1961, McGuire and McDonnell, 2006).Catchments with larger storage capacity have longer averageflowpaths (Frisbee et al., 2011, Broxton et al., 2009),connecting hydrologic inputs to deep storage systems.Hydrologic connectivity to these deep flowpaths is directlyrelated to higher concentration of weathering products, dueto longer residence time (Garrels and Mackenie 1967).Catchment response to daily input variability was measuredin two alpine headwater catchments, Green Lake 4 (GL4), inthe Colorado Front Range and Emerald Lake Watershed(ELW) in the Southern Sierra of California. Disconnectedphysical input and output rates, or input rate independentof output rate is an indicator of hydrologically significantstorage. Testing the role of physical storage at the catchmentscale requires measuring the input and output rates at thesame temporal scale, at a small enough resolution tomeasure short-term connectivity. Snowmelt-dominatedheadwater catchments provide a single hydrologic inputcontrolled by maximum snow water equivalent, topographic

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and hydrometerologic conditions. A spatially distributedsnowmelt model derived from the extrapolation of pointmeasurements of these conditions is an improvement fromextrapolation of precipitation point measurement values fortotal input to the catchment area. These hydrologic fluxes,at a daily step, over the snowmelt seasons from 1996-2006were compared. In ELW, 2006 shows a hysteresis relationship(Figure 1), which may be due to filled storage capacity fromthe previous year. Given the similar geologic terranes, weexpect hydrochemcial variability to be controlled byflowpaths through storage reservoirs. The hydrochemicalevolution of waters at the output over the snowmelt seasonshow greater flux of primary weathering products, in GL4relative to ELW and similar variability of secondary mineralweathering products in both catchments.

Dunkerley, DavidWater partitioning at the dryland soil surface: rolesof precipitation intensity variation and plant-mediated water fluxes (Invited)Dunkerley, David1

1. School of Geography and Environmental Science,Monash University, Melbourne, VIC, Australia

The partitioning of water arriving at the dryland soilsurface involves dependencies on many aspects of theprecipitation, biota, and the soil material itself. There areimportant interactions and feedbacks in the linkages amongwater, soil and biota that are incompletely explored. Rainfallsimulation has been employed in both field and laboratoryin order to explore some of these. Field experiments oncrusted dryland soils at Fowlers Gap in arid Australia haveshown that the temporal intensity profile of rainfall exerts asubstantial influence on water partitioning. For instance, arainfall event with a late intensity peak can yield a runoffratio more than 3.5 times that found in constant intensityrainfall, while the maximum flux of overland flow can bemore than 5.7 times larger. Importantly, however, the flux ofwater arriving at the soil surface is mediated by standing

vegetation and by litter resting on the soil surface, as well asby the intensity of the rainfall. Laboratory studies haveshown, for instance, that stemflow on plants also dependsnot only on the intensity of incident rainfall, but on theintensity variation through time. Events with early intensitypeaks can yield ~ 50% more stemflow than arises from rainof constant intensity. However, peak fluxes of stemflow aremaximized by late intensity peaks, and can be an order ofmagnitude larger than in constant intensity rainfall. Highstemflow fluxes are known to be capable of driving thepartitioning of water into Hortonian overland flow, thoughthis has primarily been seen in wet tropical forests, and littleis known from dryland ecosystems. Consequently, a complexpicture of interactions and feedbacks emerges in the systemprecipitation – soil – biota, that has clear implications forbuilding a full understanding of plant water availability. Afurther reason for wishing to understand these interactionsmore fully is than many appear subject to change as globalenvironmental change leads to altered rainfall eventproperties and temporal distributions.

Dunn, SamuelProduction, consumption, and transport ofmethane in alpine and sub-alpine wetlands as afunction of plant speciesDunn, Samuel1, 2; von Fischer, Joe1, 2

1. Graduate Degree Program in Ecology, Colorado StateUniversity, Fort Collins, CO, USA

2. Biology, Colorado State University, Fort Collins, CO, USA

Methane is a greenhouse gas that is produced bymicrobes under anoxic conditions. Previous work hascoupled photosynthesis and methane emissions using stableand radio isotopes of Carbon Dioxide within a greenhousesetting. However, a full understanding of the transfers andconversions of fixed carbon from the plant, through therhizosphere, and to the atmosphere as methane is lacking.The coupling of the methane and below ground carboncycles within model simulations will allow for a finerunderstanding of the role of ecosystem production inmethane emission and the potential effects of a changingclimate. In order to parameterize this model, flux rates andcarbon conversion efficiency need to be measured in situ.Using 13C-CO2, 13C-Acetate, and 13C-CH4, we conducted apulse-chase experiment in high alpine and sub-alpinewetlands dominated by Carex aquatilis and other commonwetland grasses to determine the temporal importance andrelative contribution of different pools within the methanecycle for measured emissions. We measured the flux andisotopic composition of methane from the labeled plots at ahigh temporal resolution (~ every 3 hours) over the course of48 hours after tracer addition. Flux of 13C-CH4 from theplots amended with dissolved 13C-CH4 peakedapproximately 5 hours after addition and decreasedsignificantly within 24hours. The decay of this isotopicenrichment tightly followed an exponential decay curvesuggesting density dependent diffusion of methane from thesoil to the atmosphere. Flux of labeled methane from the

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plots amended with dissolved 13C-Acetate peaked 13 hoursafter injection and decayed very slowly. Flux of labeledmethane from plots amended with 13C-CO2 appearedaround 13 hours after addition and was not detectablewithin another 12 hours. Overall methane flux rates from allplots were very similar in magnitude and varied over thecourse of the day with temperature.

Field, Jason P.Bridging from Soil to Ecosystem Goods andServices Provided by the Critical ZoneField, Jason P.1; Breshears, David D.1; Law, Darin J.1; Brooks,Paul D.1; Chorover, Jon1; Pelletier, Jon D.1; Troch, Peter A.1;López-Hoffman, Laura1; Rasmussen, Craig1; Papuga,Shirley1; Harpold, Adrian1; Biederman, Joel A.1; Barron-Gafford, Greg A.1; McIntosh, Jennifer C.1; Litvak, Marcy2

1. University of Arizona, Tucson, AZ, USA2. University of New Mexico, Albuquerque, NM, USA

Over the past decade, ecologists have sought to betterquantify the consequences of changes in ecosystems byfocusing on the “ecosystem goods and services” that theyprovide humanity and the specific ways in which theyincrease human well-being. These goods and services havebeen subdivided into “supporting”, “provisioning”,“regulating” and “cultural”. This framework has beenfurther expanded in numerous ways, including identifyingoptions associated with differentiating between location-centric vs. location-flexible stakeholders, between portableand non-portable services, and between fast, patchyecosystem change versus gradual, homogenous ecosystemchange, both of which can be driven by climate change. Thecritical zone itself provides services that overlap withecosystem services, and soils are a primary driver of suchecosystem services. Drawing on potential issues within theJemez River Basin and Santa Catalina Mountains CriticalZone Observatory, we highlight the role of soils in fourexamples: (1) How will changes in winter precipitation andsnowpack affect CZ water resources?; (2) How will changes indrought affect CZ water resources?; (3) How will a snow-rainshift affect CZ productivity- and carbon-related services?;and (4) What will determine post-disturbance recovery andchanges in associated CZ services? These examples highlightmore generally a central role for soils and associatedecohydrology in determining critical zone goods andservices, much in the way that they do for many ecosystemgoods and services.

Furman, AlexExploring Root Uptake Under High FrequencyIrrigation Using Electrical Resistivity TomographyFurman, Alex1; Garre, Sarah2; Assouline, Shmuel3; Gunther,Thomas4

1. Civil & Env. Engineering, Technion IIT, Haifa, Israel2. Gembloux Agro-Bio Tech, Université de Liège, Gembloux,Belgium

3. Soil Water and Environmental Sciences, AgriculturalResearch Organization – Volcani Center, Bet Dagan,Israel

4. Leibniz Institute for Applied Geophysics, Hannover,Germany

Root uptake and its relation to environmental factors,and primarily soil water content, are perhaps the leastunderstood component in terrestrial water balance and is ofhigh importance for water resources management, ecologyand agriculture. In this research we explore the spatial andtemporal distribution of soil water in high resolution usingelectrical resistivity tomography (ERT). Bell peppers wereplanted in a chamber and irrigated in two different schemes,differing only in irrigation frequency (daily and eight-dailyirrigation, where the daily dose is equal for both treatments).This irrigation difference results in very different spatio-temporal distribution of the soil water in the root zone,which in turn derives spatio-temporal differences in rootuptake. Experiment was conducted under a screen-house inMediterranean summer conditions, i.e. very highevapotranspiration. Resistivity surveys, using 96 electrodesplaced around the growth chamber and at soil surface(Figure 1) were taken over 10 times daily. Plants subjected tohigh frequency irrigation generally were faster in growth andmatured about a week earlier. This is primarily attributed tothe higher water content that exists in the root zone, andprimarily during the climatically stressing noon hours.Inverted images (e.g. Figure 2) provide an interesting insightinto the spatio-temporal distribution of the root uptake.This in turn can now be correlated to the spatial location ofthe roots, and to the soil induced water content dynamics.

Picture of experimental setup including growth chambers equippedwith 96 electrodes each

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An example of soil resistivity distribution

Gabriel, Carrie-EllenExamining physical and biological controls of SOMstability through depth in harvested red spruceforest soilsGabriel, Carrie-Ellen1, 2; Kellman, Lisa2; Ziegler, Susan3

1. Earth Sciences, Dalhousie University, Halifax, NS,Canada

2. Earth Sciences, St. Francis Xavier University, Antigonish,NS, Canada

3. Earth Sciences, Memorial University, St. John’s, NF,Canada

Understanding how environmental factors affect soilorganic matter (SOM) stability is important, particularly inthe context of changing landuse such as forest harvesting.Following a harvesting disturbance, soil temperature andmoisture dynamics are altered, and organic matter (OM)inputs change, resulting in a potential increase in SOMdecomposition and mobilization. The objective of this studyis to investigate mechanisms that alter SOM stability in atemperate forest soil where SOM losses have beendocumented following harvesting. To accomplish this, weexamine temperature-driven changes in respiration andwater extractable organic matter (WEOM) from soilsdiffering only in their harvest history, through depth andunder C amendment conditions that closely mimic thosefound in the field setting. Composite field moist soil genetichorizons (Ae, Bf and BC) were sampled at a paired mature(110yr) and young (35 yr) red spruce forest, incubated for 28days at 5, 15 and 25 C at optimum moisture, and sampledfor CO2 and 13C-CO2 weekly. Before and after theincubation, soils were analyzed for elemental composition,and stable isotope ratios of C and nitrogen (N). Followingthe incubation period, dissolved organic carbon (DOC) andUV-vis absorbance of WEOM was determined for eachhorizon after which the specific UV-vis absorbance (SUVA,254 nm) and spectral slope ratios were calculated. Resultsindicate a difference in SOM between the two sites. A modestincrease in elemental C and N in the Ae horizon but amarked decrease in C and N for Bf and BC horizons wasdetected in the young relative to the mature site. An order ofmagnitude difference in specific decomposition ratesbetween the shallow horizons (Ae and Bf) and the deeper soil(BC) was observed, with the Bf horizons generating thehighest rates. In Bf and BC horizons, specific decomposition

rates were generally higher at the younger site compared tothe mature site, whereas in the Ae horizons the oppositetrend was observed. For both sites, evolved 13C -CO2matched that of the bulk soil in the Ae horizon, but thesignature that emerged from the Bf and BC horizons wasmore 13C enriched than that of the bulk soil. SUVA ofWEOM was highest in Ae horizons, especially for the youngsite, but dropped off sharply through depth in the Bf andBC horizons. This was also reflected in the spectral analysis,and suggested that low molecular weight moleculesdominate at depth for both sites. These results are consistentwith a change through the profile of the source of SOM forresident decomposers following harvesting, reflectingchanges to plant inputs at the surface, but a microbialsource at depth. Microbes can readily access substrates in theBf horizons that are not present as DOC. At the younger site,SOM from the Bf and BC horizons is more susceptible todecomposition across the temperature range compared tothe mature site. These findings have implications forunderstanding key processes governing SOM stabilityfollowing forest harvesting.

Gangi, LauraIdentifying and quantifying determinants of theoxygen isotopic exchange between soil water andCO2 by combining laser-based spectroscopy andgas-permeable tubingGangi, Laura1; Rothfuss, Youri1; Brüggemann, Nicolas1;Vereecken, Harry1

1. IBG-3, Forschungszentrum Jülich GmbH, Jülich,Germany

The oxygen isotope signature of CO2 (18O-CO2) enables

partitioning the carbon gross fluxes of terrestrial ecosystemsrelated to soil respiration and plant assimilation, as CO2attains a distinct 18O value during equilibration with 18O-depleted soil water and 18O-enriched leaf water, respectively.However, the interpretation of the measured 18O-CO2 fromsoils is still challenging because the signal is influenced bydifferent parameters, e.g. the 18O of soil water (18O-H2O),CO2-H2O equilibration rate (depending on soil moisture,soil porosity and tortuosity as well as the catalytic activity ofcarbonic anhydrase), and soil physical properties which mayvary in time and space. Furthermore, the contribution ofadditional factors, e.g. respiration by plant roots, is largelyunknown. In our study, we measure the 18O-exchangebetween soil water and CO2 on-line within soil columnsfilled with well characterized medium sand and local soilmaterial, respectively. Gas-permeable microporouspolypropylene tubing is installed at different depths in thesoil columns and purged with zero air at a low flow rate. The18O of CO2 and water vapor, which is transported from thesoil into the tubing, is monitored simultaneously by laser-based spectroscopy. The isotopic signature of water vapor isthen used to infer 18O-H2O, using well-establishedcalibration equations, and, together with the 18O-CO2, thedegree of 18O-exchange between soil water and CO2 as well asCO2 diffusion through the different soil layers. We expect

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that (i) variations in 18O-H2O, soil water content, and soilphysical properties such as porosity, (ii) changes in carbonicanhydrase activity, and (iii), depending on the rate of CO2-H2O equilibration, respiration by plant roots will bereflected in the 18O-CO2. This new methodology representsa promising tool to measure stable isotope fluxes betweensoil and atmosphere in situ. It could provide usefulinformation for an improved parameterization of modelssimulating the 18O of soil CO2 fluxes, including CO2invasion from the atmosphere into the soil.

Gebhardt, MarthaSoil biotic indicators for improving native plantestablishment in disturbed SouthwesterngrasslandsGebhardt, Martha1; Fehmi, Jeff1; Rasmussen, Craig2; Gallery,Rachel1

1. School of Natural Resources and the Environment,University of Arizona, Tucson, AZ, USA

2. Department of Soil, Water and Environmental Science,University of Arizona, Tucson, AZ, USA

Arid and semi-arid ecosystems account forapproximately 40% of terrestrial land surface andconsequently play a significant role in the global water andbiogeochemical cycles. In the Southwest U.S., land usechange and non-native plant invasions are widespread andincreasing, typically resulting in losses of native plantbiodiversity that cascade to changes in hydrological andbiogeochemical cycling. Furthermore, projected warmer anddrier conditions in this region have the potential to disruptthe function and stability of ecosystems and soil resourcesthrough direct effects on soil microbiota and plant-microbeinteractions. Using a fully factorial experiment, we examinedthe interactions and feedbacks among plant species, soilamendments, and soil microbial communities to relate theseinteractions into parameters for native plant restorationsuccess in heavily disturbed soils in southern Arizona. Fieldsoil was collected from the site of a proposed mine in theSanta Rita mountains, Arizona. Two reclamationamendments, biochar and wood chip mulch, were combinedwith soil sterilization (autoclaving) to give six treatmentsthat correlate with proposed practices and soil stockpiling.Ten plant species native to southern Arizona and fourcommunity mixtures were grown in six different soiltreatments for 11 weeks in a growth chamber to evaluateplant growth rate and establishment, and bacterial, archaeal,and fungal community structure, activity, and biomass.Initial results from quantitative PCR (qPCR) indicatesterilized soils had significantly lower starting microbialbiomass than unsterilized soils across all soil amendments.Similarly, soil moisture content and water holding capacitywere lower in autoclave-sterilized soils. In the woodchip andnon-amended soils, total aboveground biomass was higherin the unsterilized soils while an opposite trend wasobserved in the soils with biochar. Both the annual and theperennial forb species studied, Eschscholzia mexicana andBaileya multiradiata, had less than 28% establishment

success. The addition of woodchips had a significantlynegative effect on plant growth and establishment successfor all ten species. Woodchip addition lowered pH comparedto other soil treatments, reduced water holding capacity, andchanged C:N ratios in soils, which together could accountfor low plant establishment. Ongoing analyses willdetermine the relative importance of nutrient availabilityand soil microbial community structure and activity acrosssoil treatments and identify key microbial taxa andfunctional groups associated with successful native plantestablishment.

Gebler, SebastianModelling soil moisture patterns with ParFlow-CLM: A comparison of high resolution modelsimulations with a sensor networkGebler, Sebastian1; Hendricks-Franssen, Harrie-Jan1; Kollet,Stefan1; Vereecken, Harry1

1. IBG-3, Forschungszentrum Jülich GmbH, Jülich,Germany

Land surface models are used for a better understandingof hydrological processes and water and energy fluxes in thesoil-vegetation-atmosphere system. However, the predictionof the spatial and temporal heterogeneity of model statesand fluxes with land surface models on small scales andhigh resolutions is still a challenge in hydrologicalmodelling. This work focuses on the comparison of soilmoisture and soil temperature measured by a sensor networkwith simulated values by ParFlow-CLM, for different levels ofmodel complexity and spatial resolution. Developed at theLawrence Livermore National Laboratory, ParFlow isdesigned to simulate fully saturated as well as variablysaturated subsurface flow fully coupled with overland flowon large scales and for high spatial resolutions. ParFlow isespecially designed to run in parallel on high performancecomputers. The Community Land Model (CLM) isembedded as a module in ParFlow which substitutes the soilcolumn of CLM to improve the representation ofgroundwater and overland flow. Like other land surfacemodels CLM describes complex processes using simplifyingassumptions and empirical approaches (e. g. neglectinglateral exchange processes). CLM was originally designed forlateral resolutions of 500 m x 500 m up to hundreds ofkilometers. In our project the integrated model ParFlow-CLM is currently applied with lateral resolutions of 10 m x10 m, 2 m x 2 m and 1 m x 1 m to the 27 ha grasslandTERENO test site at Rollesbroich located in the Eifel(Germany). This study aimed at investigating the effects ofdifferent spatial resolutions and different grid scales onParFlow-CLM simulations. Within the scope of this workthe impact of different lateral and vertical model resolutionsas well as different soil layer complexities of ParFlow-CLMare investigated and quantified for the Rollesbroich studysite to find the impact on the spatiotemporal soil moisturepatterns. Amongst others (i. e. lysimeter devices, eddycovariance towers, discharge measurements etc.) theRollesbroich study site is equipped with a wireless sensor

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network (SoilNet ) measuring soil water content andtemperature delivering long term as well as temporally andspatially high resolution information, which allows adetailed model evaluation. It is expected that an analysis andquantification of the effects of model complexity andresolution will improve the understanding of structuralmodel uncertainties and identify possible scalingdiscrepancies of the model simulations on sub catchmentscale. This will lead to more accurate simulation results forplanned high resolution ParFlow-CLM Data Assimilationstudies for Rollesbroich and other similar study sites.

Gevaert, AnoukTwo-step soil saturation mechanism at hillslopescaleGevaert, Anouk1, 2; Troch, Peter A.1; Teuling, Ryan2

1. University of Arizona, Tucson, AZ, USA2. Wageningen University, Wageningen, Netherlands

Hillslope response to rainfall events is controlled for animportant part by runoff, which is generally subdivided intoinfiltration and saturation excess runoff. This research aimsto improve understanding of the mechanisms of saturationexcess overland flow on hillslope scale. The experimentconsists of a 22-hour rainfall event with a constant intensityof 12 mm/hr that was conducted on a convergent hillslopebuilt at Biosphere 2. This event saturated a large part of thehillslope and produced overland flow in the central troughlasting from 17-19 hours after the start of the experimentuntil more than 24 hours after the rain was stopped. Soilmoisture data showed a two-step wetting process insaturated areas as shown in Figure 1. After initially steadyconditions, the arrival of the infiltration front led to a sharpfirst step in soil moisture to wetter, but still unsaturated,conditions. This step moved from the soil surface to thebottom of the soil column at a constant speed. Once thefirst step reached the bottom of the soil, a second sharp stepin soil moisture propagated from the bottom of the soilcolumn to the surface. This step led to saturated conditionsand thus marked the arrival of the saturation front. Aconceptualization of the steps dividing the hillslope intoinitial conditions and the two steps showed that saturationstarted at the bottom of the soil column in the centraltrough. From there, the second saturation step spreadupwards and to either side of the trough. On hillslope scale,saturation was observed to generally expand in the upslopedirection. The propagation of the second saturation step islinked to changes in subsurface and overland flow. Anabrupt increase in subsurface flow took place in the periodthe second step reached 50 cm depth in and along thecentral trough while overland flow started around the timethe second step reached the surface. The results of this studyprovide insight into runoff generation and the developmentof saturated areas in a hillslope in space and time.

Volumetric water content for a location in the central trough at fourdepths measured from the surface. Time is relative to the start of therainfall event.

Glatzel, StephanMethane controls the greenhouse gas budget ofrewetting fensGlatzel, Stephan1; Franziska, Koebsch1; Hahn, Juliane1;Koch, Marian1; Jurasinski, Gerald1

1. Landscape Ecology and Site Evaluation, University ofRostock, Rostock, Germany

Peatlands are able to store carbon dioxide (CO2) forextended periods of time. On the other hand, they aremethane (CH4) sources. As nitrous oxide release isuncommon in wet ecosystems, the balance between CO2uptake and CH4 release determines the radiative forcing ofthe ecosystem. Especially directly after rewetting, fens mayemit huge amounts of CH4. Generally, coastal peatlands areconsidered being less important with respect to greenhousegas emissions as salt or brackish waters contain relativelyhigh amounts of sulphate, which leads to the inhibition ofmethanogenesis because sulphate reducers outcompete themethanogens. Due to climate change and associated sea levelrise more frequent or permanent inundation of coastalecosystems is expected. Here, we report CO2 exchange byeddy covariance and CH4 emissions determined withdynamic closed chambers between 2009 and 2011 and (atleast during the two last years of study) quasi-continuouseddy covariance CH4 measurements in a coastal peatlandduring the process of rewetting. Over the course of the studyperiod, seasonal (May-Oct), CO2 storage amounted to 294 to352 g C m-2, indicating a small sink for the entire year.Interestingly, the rising water table (close to 0 in 2009, 70 cmaboveground in 2011) did not considerably alter CO2 netecosystem exchange. A sharp drop in gross ecosystemproduction (GEP) was mirrored by a strong decrease inecosystem respiration (Reco) during the first year ofrewetting. During the third, even wetter year, GEP and Recowere just a little higher that in 2010, resulting in a seasonalstorage of 352 g C m-2. In contrast, CH4 emissions changeddramatically in magnitude as the ecosystem shifted from a

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rich brackish fen over a rich, shallow, much less brackishlake to a rich, shallow, brackish lake. When measurementsstarted in 2008, the fen had been under moderate rewettingfor about a decade with water levels between 0.4 m abovesurface in winter and 0.4 m below surface in summer.Conductivity increased up to 15 mS/cm. In 2009, estimatedannual methane emissions were negligible ranging from 0.1to 3.4 g CH4 m-2 a-1 depending on dominant plant species.During the second year of study the emissions increasedhundredfold while the relative contribution of the dominantplant species and the relative seasonal pattern remainedalmost unchanged. The estimated annual emissions (80 to290 g CH4 m-2 a-1) were then well in line with findingsfrom other rewetting projects reporting relatively highmethane emissions during the first years of rewetting. In2011, the estimated annual emissions ranged between 31 and177 g CH4 m-2 a-1. Our data show that CH4 controls theradiative forcing in freshly rewetted fens flooded by sweetwater. We expect an increase in salinity and decreasingmethane emissions. Together with the results above we willpresent the latest data from the ongoing measurements andevaluate whether this notion can be supported.http://www.auf-loe.uni-rostock.de/mitarbeiter/stephan-

glatzel/

Haberer, Christina M.Oxygen transfer in the capillary fringe: Impact ofphysical heterogeneity and transient flowconditionsHaberer, Christina M.1; Rolle, Massimo1, 2; Cirpka, Olaf A.1;Grathwohl, Peter1

1. Department of Geosciences, University of Tübingen,Tübingen, Germany

2. Department of Civil and Environmental Engineering,Stanford University, Stanford, CA, USA

Oxygen transfer across the capillary fringe (CF) toanoxic groundwater is of primary importance for a widevariety of biogeochemical processes occurring in theinterface region between the unsaturated and the saturatedzone. Mass transfer of O2 in the CF is thereby controlled bydiffusive/dispersive transport as well as mass exchangebetween entrapped air and groundwater. In addition,transient flow conditions and the presence of physicalheterogeneity in the porous medium strongly affect the O2-fluxes to anoxic groundwater. We performed quasi 2-Dflow-through laboratory experiments (Fig. 1) to study theeffect of a coarse-material inclusion, located in proximity ofthe water table, on flow and O2-transfer in the CF. Flow andtransport were monitored under both steady-state andtransient flow conditions, the latter induced by a fluctuatingwater table. We visualized the complex flow field using a dyetracer solution, measured O2-profiles across the CF, anddetermined O2-fluxes at the outlet of the flow-throughchamber. Our results show that O2-transfer was significantlyaffected by the coarse-material inclusion during the differentphases of the experiment. At steady state, the O2-flux acrossthe CF was considerably enhanced due to flow focusing in

the fully water-saturated coarse-material lens. Duringdrainage, the capillary barrier effect prevented water to drainfrom the fine material overlying the coarse lens. Theentrapped O2-rich aqueous phase contributed to the totalamount of O2 supplied to the system when the water tablewas raised back to its initial level. In case of imbibition,pronounced air entrapment occurred in the coarse lens,which caused O2 to partition between the aqueous andgaseous phases. The amount of O2 transferred to the anoxicgroundwater was up to 7 times higher in the heterogeneoussystem compared to an equivalent experiment performed ina homogeneous porous medium. Our results show thatknowledge about the interaction of porous mediumheterogeneity, transient flow dynamics, and mass transferprocesses is needed to improve our understanding of theexchange of volatile compounds across the CF and to predictredox conditions and reactive transport in underlyingshallow groundwater systems.

Fig. 1. Experimental setup with inner dimensions of 80 cm 40 cm 0.5 cm (L H W). To visualize the flow field New Coccine (CAS:2611-82-7, Conc. = 75 mg L-1) was used as a red dye.

Hagmann, DianeEffect of heavy metal contamination on selectedextracellular enzyme activities in soilHagmann, Diane1; Mathieu, Carolyn1; McGlone, Cherrelle1;Krumins, Jen1; Goodey, Nina1

1. Montclair State University, Westfield, NJ, USA

The overall goal of this research is to investigate theenzyme activities of soils collected from a heavy metalcontaminated area where study sites lie along a gradient ofincreasing metal load. Our hypothesis is that heavy metalcontamination impacts the microbial communities in thesoil and consequently the extent of nutrient cycling. We haveselected three enzymatic activities as representative of C, P,and N cycling. We have so far optimized the phosphataseand cellobiosidase activities using the substrates 4-MUB-cellobioside and 4-MUB-phosphate for analyzingcontaminated soil. The following assay conditions wereinvestigated: the preparation of the soil slurry (sonicationversus blending), assay temperature, pH, and the amount ofsoil required for the assay. Enzyme activities were determinedby following the kinetics of product formation usingfluorescent substrate analogues and the enzyme activities

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were expressed in pmoles of product formed per /g of drysoil /hr. We also investigated the relationship betweenparticle size of the soils and enzyme activity using sieves withdifferent pore sizes. Herein we present data that show theeffects of assay conditions on the phosphatase andcellobiosidase activities and results from assaying ourcontaminated study sites for enzymatic activity.

Hall, StevenSynergies Among Oxygen and Iron in the CarbonCycle of Humid Tropical Forest SoilsHall, Steven1; McNicol, Gavin1; Silver, Whendee L.1

1. Environmental Science, Policy, and Management, UCBerkeley, Berkeley, CA, USA

Humid tropical forests harbor a large portion of globalsoil carbon (C), yet they simultaneously support the highestrates of litter decomposition of any biome. Variation in soiloxygen (O2) availability concomitant with high precipitationhas been proposed as a mechanism underlying soil Caccumulation in these ecosystems, as these wet upland soilsshare characteristics of both terrestrial and aquaticenvironments. Here, we examined how soil carbon (C) poolsand turnover varied with long-term mean O2concentrations, which decreased across a toposequence fromridges, slopes, to riparian valleys. We also assessedrelationships between C turnover and reactive iron (Fe) andaluminum (Al) minerals, which are thought to stabilize C.We separated C in soil samples (n = 30) according to densityand occlusion using sodium polytungstate solution andsonication, yielding a free light, occluded light, and mineral-associated fraction. We analyzed radiocarbon (14C) contentin the heavy fraction to provide a proxy for turnover time.Concentrations of Fe and Al were measured in citrate-ascorbate and ammonium oxalate extractions.Mineral-associated C concentrations in surface soils (0-10cm depth) were significantly greater on ridges (48 2 mg g-1) than on slopes or riparian valleys (33 3 mg g-1), whereasthe light C fractions did not differ. In subsurface (10 – 20cm) soil, occluded light fraction C was greater in valleys(4.7 1.8 mg g-1) than ridges or slopes (2.7 0.5 mg g-1).These results suggest that O2 limitation may promote theaccumulation of occluded light C in riparian valleys, but notmineral-associated C. Radiocarbon content of mineral-associated C was similar among all topographic positions in0 – 10 cm soil (79 5 ‰ 14C), reflecting accumulation ofbomb-enriched 14C. A simple model suggested turnovertimes of approximately 100 years for mineral-associated C.Subsurface (10 – 20 cm) soils on slopes, however, weresignificantly depleted in 14C (40 14 ‰) relative to ridgesand valleys. This may reflect the removal of soil vialandslides occurring over decadal scales, exposing soils witholder C. Mineral-associated C concentrations and their 14Ccontent increased with oxalate-extractable Fe and Al,whereas 14C declined with citrate-ascorbate extractable Fe(p < 0.01). These extractants could reflect Fe pools withdistinct effects on C cycling. Complexes between oxalate-extractable Fe and organic matter lead to accumulation of C

that cycles over decadal scales. The citrate-ascorbateextraction reflects Fe that is potentially reducible bymicrobes, and thus can support anaerobic respiration. Totalsoil C concentrations decreased with citrate-ascorbate Fe atthe landscape scale, potentially reflecting the importance ofmicrobial Fe reduction in limiting C accumulation underanaerobic conditions. Thus, O2 availability may exertcomplex effects on soil C storage in humid tropical forests:occluded light C accumulates in soils with low O2concentrations, whereas the availability of reducible Feoxides to sustain anaerobic respiration may limit theaccumulation of mineral-associated C. These findingsillustrate couplings between hydrology, geomorphology, andmineralogy that impact C cycling in humid tropical forestsoils.

Harman, Ciaran J.PERTH and the Dynamic Age Function: Atheoretical and experimental framework forunderstanding residence and transit times intransient, complex flowsHarman, Ciaran J.1; Kim, Minseok1

1. Department of Geography and EnvironmentalEngineering, Johns Hopkins University, Baltimore, MD,USA

In many natural systems (from soil to hillslope tocatchment scale) it is difficult to characterize and modeltransport due to the complexity and variability of flowprocesses. An alternative approach is to consider thetransport through a defined control volume in terms of thetransit time and residence time distributions. However,observations of transit time distributions have largely beenlimited to approximating the transit time distribution astime-invariant. A new theoretical framework has recentlybeen developed (Botter et al 2010, 2011) to represent solutetransport under time-varying flow conditions at hillslopeand watershed scales. This framework provides a rigorousalternative to the convection-dispersion equation, whichcannot feasibly be applied to complex flows. However theframework is incomplete, as the form and controls on a keyelement of this framework, the ‘age functions’, are notspecified from theory and must be investigated empirically.Based on a modified version of this framework, we havedeveloped an experimental method, named the PERiodicTracer Hierarchy (PERTH) for making direct observations ofthe age function. This approach does not involve selecting afunctional form for model fitting, but rather estimates theage function directly from the data. The method involvessetting up a periodic flow condition in the system. Thisperiodic condition creates multiple instances of a single‘effective’ transient condition that can be probed by repeatedapplication of tracers at different moments during the event.We deploy tracers in a hierarchical manner to simultaneouslyA) account for the problem of tracers injected several timesover-printing each other in the output breakthrough curvesB) obtain observations of the age function at multipletemporal resolutions and C) look at both fast and long-time-

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scale behavior. We will present the new framework, and theexperimental method, along with preliminary proof-of-concept model results.

Harpold, Adrian A.Snowmelt Infiltration Dynamics in SeasonallySnow-Covered Areas of the Western U.SHarpold, Adrian A.1; Molotch, Noah P.1

1. Institute of Arctic and Alpine Research, University ofColorado-Boulder, Boulder, CO, USA

Water released from melting snowpacks is critical forstreamflow generation, biogeochemical cycling andtransport, and the productivity of forests late into thegrowing season. Snowmelt infiltration dynamics aregoverned by melt water inputs controlled by the snowpackenergy balance, as well as losses from the soil profilemediated by the soil hydraulic properties, terrain, andevapotranspiration (ET) demand. Despite the importance ofsnowmelt to the water budgets of headwater catchments, itremains unclear how snowmelt infiltration dynamics arerelated to the timing and size of seasonal snowpacks. In thisstudy we apply data from over 200 Snow Telemetry(SNOTEL) stations across the Western U.S. with at least fouryears of soil moisture, temperature, and snowpack records,for a total of nearly 1000 station-years. We ask the researchquestion: “When and where are snowmelt infiltrationdynamics principally controlled by the magnitude andtiming of seasonal snowpacks?” Our results showed thatroughly half of all station-years had peak soil moisturecoincident (within 3 days) with snow disappearance. Thissynchronicity likely results from snowpack infiltration ratesexceeding soil profile loss rates (e.g. percolation, runoff, andET) during times when melt is still occuring (e.g. beforesnow disappearance). Roughly a fifth of the station-yearshad peak soil moisture within >3 days after snowdisappearance, which is often due to late seasonprecipitation. Greater than a quarter of the station-years hadpeak soil moisture >3 days prior to snow disappearance,which suggested that losses from the soil profile began toexceed snowmelt infiltration rates. Peak soil moisturepreceding snow disappearance was more prevalent in warmerand/or more southerly stations and is consistent with earlier,large losses due to ET or drainage in those environments.Our results highlight two important ramifications regardingthe synchronicity of snowpacks and the delivery of snowmeltwater to the soil profile: 1. Snowmelt infiltration raises soilmoisture stores up until high ET losses or saturation (e.g.melt rates generally exceed percolation rates) and 2. Somestations had more consistent partitioning of early seasonsnowmelt (e.g. able to draw down soil moisture stores duringsnowmelt) in very wet and dry winters. Because forests abilityto transpire melt water also depends on factors other thanwater availability, such as temperature and light, not alllocations were able to utilize early season melt water fortranspiration. More work is needed to understand how theseobservations of snowmelt infiltration dynamics could alterwater availability for vegetation and the cycling of carbon

and nutrients in montane forests, particularly in light of theearlier and faster snowmelts expected in the coming decades.

Hinckley, Eve-Lyn S.The Critical Zone as a Driver of Ecosystem NRetention and Transport in the Colorado FrontRangeHinckley, Eve-Lyn S.1, 2

1. Institute of Arctic and Alpine Research, Boulder, CO,USA

2. NEON, Boulder, CO, USA

Over a decade of research in the alpine zone of theColorado Front Range has shown that nitrogen (N)deposition originating from low elevation, developed areashas changed ecosystem stoichiometry, microbialtransformation rates, and aquatic community structure.Markedly less research has occurred in mid-elevation forests,which sit at the current snow line and are vulnerable toclimate change impacts on precipitation and temperature,increased N loading, and disturbance by wildfire and pinebeetle outbreaks. Tracer experiments using 15N-nitrate andlithium bromide (LiBr) during spring snowmelt and thesummer monsoon season (the major hydrologic events inthese systems) point to the governing roles that aspect andsoil properties (e.g., organic matter content, macroporosity,and depth to saprolite) play in determining the fate ofatmospheric N. This research, conducted in a mid-elevationforested catchment within the Boulder Creek Critical ZoneObservatory, demonstrates stark contrasts between south-and north-facing slopes with respect to the fate ofatmospheric N. South-facing slopes, characterized by higherinsolation, shallow soils (0.25-0.3 m), and preferential flowpaths, rapidly transport water and reactive N to depthduring major hydrologic events. In contrast, north-facingslopes, characterized by lower insolation, thicker soils (0.4-0.45 m), and periods of sustained water flow through aconnected soil matrix, have greater ecosystem N retentionand lower N losses to groundwater and streams. The largestbiological sink for N was the microbial community, whichsequestered approximately 50% of applied 15N in north-facing slope soils, and 16-34% of applied 15N in south-facingslope soils during the snowmelt period when populationswere largest. The results from this research lend importantinsight into how critical zone structure affects coupling ofhydrologic response and biogeochemical processes at point,hillslope, and catchment scales. In addition, it leads tointeresting new questions about whether ‘legacy effects’ ofthe current critical zone will buffer patterns of ecosystem Nfates as climate, N deposition, and disturbance continue toalter this landscape over short time-scales.

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Hinz, ChristophState transitions in the artificial catchmentHuehnerwasser (Chicken Creek): Ecosystemsdevelopment 8 years after initialisationHinz, Christoph1; Gerwin, Werner1; Schaaf, Wolfgang1;Elmer, Michael1; Fluehler, Hannes2; Hollaender, Harmut3;Huettl, Reinhard1, 4

1. Brandenburg Technical University Cottbus, Cottbus,Germany

2. Swiss Federal Institute of Technology, Zurich,Switzerland

3. University of Manitoba, Winnipeg, MB, Canada4. GFZ German Research Centre for Geosciences, Potsdam,Germany

In 2005 an artificial catchment with an area of 6 ha wasconstructed in Lusatia (150 km southeast of Berlin,Germany). It consists of 1-2 m thick clay lining covered by 2-4 m quaternary sandy and loamy sediments that were placedwith droppers and dozers used in lignite mining. Thecatchment is gently sloped and has a small lake at thebottom. During the initial phase of development thecatchment changed very rapidly due to sediment transport,drainage network formation, and soil crusting very similar togeomorphic processes observed in arid and semi-aridlandscapes void of dense vegetation. Hydraulic propertieschanged rapidly after few wet and dry cycles, indicative ofparticle mobilisation and trapping in the subsurface.Accordingly, the hydrological regime was controlled by rapidsurface runoff enhanced through crust formation and at thesame time a shallow ground water system developed. Thissurface runoff regime peeked about two years initialisationas shown by a maximum area of drainage channels. A major,fairly rapid transition occurred between three and five yearsafter placement, in which the sediment transport ceased andvegetation coverage of the drainage channel exceeded 90%.The transition represents the onset of a transpirationdominated regime that is further enhanced by change of theplant composition of the vegetation with tree recruitmentfrom the surrounding forming significant clusters in thecatchment. This transition in the third year was also seen ina significant increase in soil fauna and plant diversity. Wepropose a simple framework that explains the catchmentevolution as a result of competing feedbacks influenced bythe initial conditions and the atmospheric drivers such asrainfall intermittency and intensity. The first stage of theevolution is dominate by abiotic feedbacks triggered byrainfall and subsequent fluid flow causing particlemobilisation on the surface and in the subsurface leading toflow concentration or in some instances to densification ofsurface and subsurface substrates. Subsequently, abiotic-biotic feedbacks start to compete in the sense that biologicalactivity generally stabilizes substrate by preventing particlemobilisation and hence contribute to converting thesubstrate to a habitat. We suggest that these competingfeedbacks may generate alternative stable states in particularunder semi-arid and arid climatic conditions, while intemperate often energy limited environments biological

process “outcompete” abiotic processes leading to a stablestate, in particular from the water balance point of view forcomparable geomorphic situations.

Holländer, HartmutImpact of modellers’ decisions on hydrological apriori predictionsHolländer, Hartmut1, 2; Bormann, Helge3; Blume, Theresa4;Buytaert, Wouter5; Chirico, Giovanni B.6; Exbrayat, Jean F.7, 8;Gustafsson, David9; Hölzel, Herwig1; Krausse, Thomas10;Kraft, Philipp7; Stoll, Sebastian11; Blöschl, Günter12; Flühler,Hannes11

1. University of Manitoba, Winnipeg, MB, Canada2. Brandenburg University of Technology, Cottbus,Germany

3. University of Siegen, Siegen, Germany4. GFZ German Research Centre for Geosciences, Potsdam,Germany

5. Imperial College London, London, United Kingdom6. Università di Napoli Federico II, Naples, Italy7. University of Giessen, Giessen, Germany8. University of New South Wales, Sydney, NSW, Australia9. Royal Institute of Technology KTH, Stockholm, Sweden10.University of Technology Dresden, Dresden, Germany11. ETH Zurich, Zurich, Switzerland12.TU Vienna, Vienna, Austria

A group of catchment modellers predicted thehydrological response of a man-made 6 ha catchment in itsinitial phase (Chicken Creek) without having access to theobserved records. The prediction exercise was organized inthree steps: (1) for the 1st prediction modellers received abasic data set describing the internal structure of thecatchment (somewhat more complete than usually availableto a priori predictions in ungauged catchments). They didnot obtain time series of stream flow, soil moisture orgroundwater response. (2) Before the 2nd improvedprediction they inspected the catchment on-site andattended a workshop where the modellers presented anddiscussed their first attempts. (3) For their improved 3rdprediction they were offered additional data by chargingthem pro forma with the costs for obtaining this additionalinformation. Table 1 summarizes the relative dischargeprediction “success” for the first three years of thiscatchment. The 1st prediction was a difficult task becausethe modellers were confronted with three special features ofthe newly constructed catchment, (i) the initially dry soil, (ii)the impact of an unusually intensive snowmelt event, (iii)which enhanced the gully formation on the not yet stabilizedbare surface. The 1st predictions for the 2nd year weresomewhat better. The real progress was made with the 2ndprediction after the field visit and the discussions among themodellers during the 1st workshop. Adding additional datafor the 3rd prediction improved those made for the 2nd butnot those for the 3rd year and even decreased the predictiveaccuracy of several models in the last step. The differencesbetween the 1st and 2nd prediction were definitely largercompared to those between the 2nd and 3rd prediction. This

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underpins the value of soft information (field visit,workshop discussions, and experience). However, localmeasurements such as infiltration tests – provided for the3rd prediction – certainly contributed to the improvedpredictions as well. They were apparently better suited todefine the soil parameters than those estimated based onpedotransfer functions.

Table 1. Rating of prediction progress compared to measurements inthe course of consecutive model improvements (0 = poor to 3 =good).

Huber, David P.Climate Controls on Soil Hydrological andNutrient Partitioning in Dryland EcosystemsHuber, David P.1; Lohse, Kathleen A.1, 2; Germino, MatthewJ.3

1. Biology, Idaho State University, Pocatello, ID, USA2. Geosciences, Idaho State University, Pocatello, ID, USA3. Forest and Rangeland Ecosystem Science Center, UnitedStates Geological Survey, Boise, ID, USA

Globally, ecosystems are undergoing dramatic changesdue to altered climate and invasion of exotic plant species.Changing climate is expected to alter the magnitude,seasonality and variability of precipitation over the nextcentury while shifts in vegetation alter fire regimes andecosystem function. Both changing hydroclimate and shiftsbetween woody and herbaceous vegetation alter theavailability and distribution of water in a landscape.Numerous studies have raised concerns that changes inhydroclimate will alter carbon (C) and nitrogen (N)partitioning but to date, the majority of ecosystem scaleclimate change studies have focused on temperature andcarbon. This is especially true for dryland ecosystems, whichrepresent more than a third of the terrestrial surface. Despitethe fact that nutrient dynamics are critical to drylandecosystem function and are sensitive to hydroclimate, nolong-term experimental studies have examined how Npartitioning varies with water availability in drylandenvironments. We use an existing long-term ecohydrologicexperiment (Est. 1993) located in southeastern Idaho toevaluate ecosystem response to changing precipitationpatterns and shifts in vegetation. The experiment consists of3 replicated blocks of 2 vegetation types (a sagebrush steppeassemblage and monocultures of crested wheatgrass, CWG)and 3 irrigation treatments representing shifts inprecipitation seasonality. Samples were collected during the2011 and 2012 growing seasons. We predicted thatdifferences in soil water availability first, and stoichiometrysecond, which vary between treatments, would control soilnutrient availability and process rates. Preliminary result

show water availability has a significant effect on N cycledynamics but varies greatly with both space and time.Regression analysis was stratified by wet versus dry years. Forwet years, multiple regression of net N mineralization showsthat 42.2% of the variability is explained by vegetation typeand soil moisture (F=13.75, P=4.536e-05), with precipitationtreatments having little influence. In addition, nitrificationrates and available NO3- pools are significantly lower inCWG versus sagebrush treatments (P<0.05). During dryyears, vegetation treatments show no significant differencesin N process rates. These findings suggest that sagebrushand CWG exert strong and differential controls over seasonalN dynamics. For dry years, 65.6% of the variability in Nmineralization rates is explained by precipitation treatments,total N, and pH (F=8.62, P=0.0002), suggesting that plantmediated control on N partitioning is dependent onadequate water availability and varies with longer (i.e.annual) moisture patterns. This inter-annual variability inprecipitation and N partitioning likely minimizes differencesin the integrated long-term N processing signal betweentreatments by prohibiting any net directional trend.Observations of total soil N pools and 15N values to adepth of 1 m support this neutral N partitioning signal withno significant differences between precipitation orvegetation treatments.

Jaisi, DebA REVERSE PATHWAY OF PHOSPHORUSCYCLING IN AGRICULTURAL SOILSJaisi, Deb1; Joshi, Sunendra1; Li, Xiaona1

1. Plant and Soil Sciences, University of Delaware, Newark,DE, USA

Commercial phosphorus (P) fertilizers are applied toagricultural crops in order to increase crop yields. Becausecrops cannot uptake all applied P, residual P accumulates insoil over time and may remain as recalcitrant P. Tounderstand bioavailability and exchange of inorganicphosphate (Pi) in different soil phases, we performedsequential extraction of soil samples collected during sixgrowth stages of a corn crop and phosphate oxygen isotoperatios (18Op) of each Pi phase measured. Our resultsshowed that the 18OP values of HCl-Pi were similar to thatof NaOH-Pi, HCO3-Pi, and H2O-Pi phases. This resultconfirms that the fertilizer P applied in the farm undergoesinterspecies transfer and becomes gradually unavailable as itultimately precipitates as apatite mineral. This trend isopposite to that of non-agricultural environments whereweathering and dissolution of minerals supplies P to plantsand microorganisms. These results are expected to havesignificant implication on current nutrient managementpractices.

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Kelley, Christopher J.A decade of water and nitrate fluxes from adryland agricultural headwater catchment: Linkinghydrologic and biogeochemical drivers of the soil NcycleKelley, Christopher J.1; Keller, C. K.1; Smith, Jeffrey L.2;Hyuck Orr, Cailin1; Evans, R. D.3

1. SoE, Wash. State Univ., Pullman, WA, USA2. ARS, USDA, Pullman, WA, USA3. SBS, Wash. State Univ., Pullman, WA, USA

Long-term monitoring sites are crucial tounderstanding connections among climate, soil hydrology,and biogeochemical controls on nutrient export fromagroecosystems. For over a decade we have monitoredseasonal and interannual variations in water and Ndischarge from a tile-drain section of the Cook AgronomyFarm (CAF), a Long Term Agroecological Reserve (LTAR) inthe Palouse Basin of eastern Washington State. We usedfield-measurement and modeling methods to capture lowerand higher-end estimates of monthly and yearly water andnitrate fluxes. Mean precipitation during the study was 495mm (SD 74). Mean measured and modeled TD water fluxeswere 80 mm (SD 40) and 158 mm (SD 60) respectively. Meanmeasured and modeled TD nitrate fluxes were 12 kg N/ha/yr(SD 7) and 20 kg N/ha/yr (SD 13) respectively (see figureattached). Based on the measured and modeled nitratefluxes between 14 and 21% of the yearly applied fertilizer isleached from the CAF each year. Previous research applyingstable N and O isotope ratios of nitrate concluded there weretwo sources of nitrate in TD discharge. The high-dischargeseason (January - May) source of nitrate was nitrifiedammonium fertilizer (~96% of the yearly leached nitrate).The low-discharge season (June - December) source wasmineralized soil organic nitrogen (SON) (~4% of the yearlyleached nitrate). We hypothesize that the source of leachednitrate shifts from nitrified fertilizer to mineralized SONbecause of changes in soil-water flow paths rather thanchanges in the soil nitrogen cycle processes. We suggest thatboth mineralization of SON and nitrification of fertilizeroccur year round. During the high-discharge season, nitratecontribution from mineralization of SON to the tile-drain isimperceptible compared to leaching of nitrified fertilizerfrom the top ~15 cm of soil. Then during the low-dischargeseason vertical transport pathways shut down as the upperprofile dries, at which point mineralized SON becomes thesole source of leached nitrate though the tile drain. If ourhypothesis is correct, changes in precipitation rates ortiming that alter typical runoff/ infiltration patterns candramatically change the timing and rate of nitrogen losses.Our research has implications for decreasing managementcosts, improving nitrogen use efficiency, and managingnitrogen losses in dryland agriculture.

*These values are know to over-estimate fluxes, based on samplingbias of peak events.

Kelly, Anne E.Deep soils allow anomalously high productivity andlimit summer drought stress in California coniferforestsKelly, Anne E.1; Fellows, Aaron W.1

1. Earth System Science, UC Irvine, Irvine, CA, USA

Understanding the processes that link biomass,production, and soil depth is critical to understanding thestructure, function, and water use of present ecosystems. Anaccurate mechanistic model is critical to predicting futurespecies distributions in a changing climate. Research on themontane conifer forest in California has found highbiomass, high productivity, and high evapotranspirationthat are well above values predicted by bioclimatic models.Traditional temperature/precipitation models (e.g., Whitaker1975) predict steppe or open woodland where sequoia grovesare found. Evapotranspiration (ET) models predict potentialevapotranspiration below measured actualevapotranspiration in many locations, especially in summerdrought conditions in large-statured conifer forest. The onlyway to resolve this apparent paradox of lush, productiveforests in a Mediterranean climate is if vegetation is able toaccess deep soil water throughout the dry summers. In thisstudy, we measured actual evapotranspiration at eddy fluxtower sites across ten diverse California ecosystems andextrapolated ET across California using the MODISNormalized Difference Vegetation Index (Goulden et al.2012). We used gridded PRISM temperature andprecipitation data along with the ET map to determine soilwater storage. We found that soil water storage and effectiverooting depth across much of California is much higherthan previously thought, with especially large discrepanciesin the conifer forests. We also examine the case study of asite in a Sierra Nevada mixed conifer forest that exhibitsyear-round growth, high ET, and little drought stress despitedry summers and snowy winters. We show using direct andindirect methods that rooting depth and soil water storageat this site far exceed conventional prediction. Because of thestrong heterogeneity of soil depth and soil water storageacross California, our results show potentially important

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limitations on future ecosystem distributions with climatechange.

Kirchner, James W.Universal fractal scaling in stream chemistry and itsimplications for solute transport and water qualitytrend detection (Invited)Kirchner, James W.1

1. Environmental System Sciences, ETH Zurich, Zurich,Switzerland

The chemical dynamics of lakes and streams affect theirsuitability as aquatic habitats and as water supplies forhuman needs. Because water quality is typically monitoredonly weekly or monthly, however, the higher-frequencydynamics of stream chemistry have remained largelyinvisible. To illuminate a wider spectrum of water qualitydynamics, rainfall and streamflow were sampled in twoheadwater catchments at Plynlimon, Wales, 7-hourly for 1-2years and weekly for over two decades, and were analyzed for45 solutes spanning the periodic table from H+ to U. Herewe show that in streamflow, all 45 of these solutes –including nutrients, trace elements, and toxic metals –exhibit fractal 1/f^alpha scaling on time scales from hours todecades (alpha=1.050.15, meanstandard deviation). Weshow that this fractal scaling can arise through dispersion ofrandom chemical inputs distributed across a catchment.These 1/f time series are non-self-averaging: monthly, yearly,or decadal averages are roughly as variable, one from thenext, as individual measurements taken hours or days apart,defying naive statistical expectations. (By contrast, thestream discharge itself is non-fractal, and is self-averaging ontime scales of months and longer.) In the solute time series,statistically significant trends arise much more frequently,on all time scales, than one would expect from conventionalt-statistics. However, these same trends are poor predictorsof future trends – much poorer than one would expect fromtheir calculated uncertainties. Our results illustrate how 1/ftime series pose fundamental challenges to trend analysisand change detection in environmental systems.

Klatt, SteffenAssessing water, carbon and nitrogen fluxes on thelandscape scale by coupling LandscapeDNDC, aregional multi-ecosystem biogeochemical model tothe hydrological model CMFHaas, Edwin1; Klatt, Steffen1; Kraus, David1; Butterbach-Bahl, Klaus1; Breuer, Lutz2; Kraft, Philipp2; Wlotzka,Martin3; Heuveline, Vincent3

1. Institute of Meteo. and Climate Research, KarlsruheInstitute of Technology, Garmisch-Partenkirchen,Germany

2. Institute of Landscape Ecology and ResourcesManagement, Justus-Liebig-University of Giessen,Giessen, Germany

3. Engineering Mathematics and Computing Lab,Interdisciplinary Center for Scientific Computing (IWR),Heidelberg University, Heidelberg, Germany

The rise in global population causing a growing fooddemand can only be satisfied by an intensification of foodproduction systems. This will affect the terrestrial carbonand nitrogen cycles significantly resulting in environmentalconsequences such as increased water use, surface watereutrophication, changes in soil carbon stock and fertility andvarious greenhouse gas (GHG) emissions as agriculturalsystems are major sources of anthropogenic GHG (e.g. CO2,CH4, N2O). Ecosystem models are suitable tools to studythe intrinsic carbon, nitrogen and water cycle from microbialprocesses to plant growth. LandscapeDNDC is abiogeochemical process based simulation system capable ofmodelling carbon and nitrogen cycling for variousecosystems such as forest, arable and grassland ecosystems.It was derived from the DNDC family of biogeochemicalmodels. It uses a generalized process description for the soilbiogeochemistry. As such it unites various DNDC modelsleading to one general model being capable of simulatingbiogeochemical processes in grassland, cropland and forestecosystems. This allows for transient simulations ofalternating ecosystems (land use change). Furthermore,different species types can be simulated sequentially(conventional agricultural or forest management) as well asconcurrently (multi-cropping and agroforestry). Thesimulation system permits regional scale applications byprocessing many time-synchronized grid cells where each cellhas its individual model setup / configuration. Beingsynchronized with respect to time facilitates coupling withexternal regional models, e.g. hydrological modelssuperimposing lateral transport of water and nutrients onLandscapeDNDC’s domain. A coupling of LandscapeDNDCto the catchment modelling framework CMF allowingsimulations of carbon and nitrogen cycling on the landscapescale has been performed. To illustrate the capabilities ofLandscapeDNDC, we will present a study that illustratesresults of a regional coupled biosphere – hydrospheresimulation including: - Various ecosystem types -Agricultural & forest management and practice - Transientsimulation of land use change - Multi-cropping andagroforestry - Nutrient (nitrate) transport due to water

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fluxes in the saturated and unsaturated zone and theirconsequences to plant growth and the soil biogeochemistry,nitrification / denitrification, GHG emissions etc.; -Nutrient eutrophication

Knadel, MariaFusing Proximal Sensing Data for OptimalLocations of Soil Moisture Monitoring StationsKnadel, Maria1; Schelde, Kirsten1; Thomsen, Anton1;Andersen, Mie2; Greve, Mogens H.1

1. Dept. of Agroecology, Aarhus University, Tjele, Denmark2. Dept. of Geosciences and Natural ResourceManagements, University of Copenhagen, Copenhagen,Denmark

The local water balance and ground water recharge aregoverned by soil texture, soil moisture and vegetationdevelopment. The complicated nature of these factors andtheir high spatial variability is challenging whenrepresentative sampling and monitoring areas at differentscales need to be selected. The aims of this work werethreefold: (1) to characterize soil variability with soil andvegetation sensors, (2) to identify hydrologically uniformregions based on the c-means clustering of the multiplesensory data, (3) to select optimal locations for monitoringnetworks of wireless sensors to capture soil moisture spatialand temporal variability. Mobile sensors are attractingincreasing attention due to their large potential forgenerating extensive amounts of data with high spatialresolution. A sensor fusion approach including in-situ andproximal sensing techniques of soil and canopy for thedetection of patterns in the soil-vegetation systems and forsoil moisture and canopy monitoring was applied in thisstudy. The instrumentation included: Veris mobile sensorplatform [with electrical conductivity, temperature and nearinfrared spectroscopy (NIRS) sensors], MobilTdr - timedomain reflectometry (TDR) mobile sensor for soil watercontent analysis and MobilLas canopy optical instrumentgenerating vegetation spectral indices. NIRS was used tocollect soil spectra for predicting soil total organic carbon(TOC) and texture. Kriging maps of both soil and vegetationsensory data and additional maps of selected digitalelevation model (DEM) derivatives were generated for twoagricultural fields in Skjern River catchment, Denmark.Management Zone Analyst software was used to clustervariables relevant to hydrological parameters of the fields.Three clusters representing hydrologically uniform unitswere obtained in each field. Within each of the three unitsmonitoring networks of manual TDR probes were installedfor further soil moisture analysis (Figure). The fusion ofhigh resolution sensory data on soil and vegetationproperties provided a detailed characterization of within-fields variation of soil and vegetation properties and adelineation of fairly uniform hydrological regions.

Koch, JoshuaRunoff sources and flowpaths in a partiallyburned, upland, boreal catchmentKoch, Joshua1; Striegl, Robert2; Ewing, Stephanie3;Wickland, Kimberly2; Kikuchi, Colin4

1. Alaska Science Center, US Geological Survey, Anchorage,AK, USA

2. Branch of Regional Research, US Geological Survey,Boulder, CO, USA

3. Department of Land Resources and EnvironmentalSciences, Montana State University, Bozeman, MT, USA

4. Department of Hydrology and Water Resources,University of Arizona, Tucson, AZ, USA

Climate change is resulting in significant changes inboreal catchments, including permafrost thaw and increasedfire. Predicting the effect of these changes on aquaticecosystems and critical subsistence species will requiregreater understanding of boreal catchment hydrology andthe processes responsible for runoff generation and soluteproduction. Runoff from boreal catchments is complex,involving flow through a patchy matrix of organic andmineral soils with varying hydraulic conductivities. Flow isconstrained in some places by the presence of permafrostand aided by preferential flow through soil pipes and areasthat remain saturated. Soil residence times and flushing

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exert substantial control on catchment carbon cycling andthe flushing of carbon, nitrogen, and mercury into the rivernetwork. In order to constrain the sources of runoff to thestream we studied two catchments in the White Mountainsof interior Alaska. We rely on permeameter measurementsand infiltration tests, porewater and surface water chemistry,stream tracer additions and end member mixing models. Wefind that approximately 25% of infiltration moves quicklythrough shallow organic flowpaths, while the remainder ofthe water infiltrates into deeper soils that are seldomsaturated and often do not contribute to streamflow.Kilometer-scale tracers show that runoff is evenly distributedalong stream reaches in the early summer, but once theactive layer thaws, inflows are greatest near surface waterbodies and beneath steep slopes. In a late-summer tracerstudy, these waters displayed a uranium isotope signatureconsistent with thawing permafrost, indicating the existenceof deep flow through the mineral soils. Trends in endmember mixing models suggest that in fine, loess soils,burned hillslopes may contribute disproportionately torunoff, potentially due to the formation of macropores andpipe flow. These results have implications forbiogeochemical cycles: labile carbon is predominantlyexported early in the summer when subsurface flowpaths arestill frozen. Carbon still reaches the stream rapidly in the latesummer, but is more recalcitrant. Nitrogen commonly limitsaquatic biogeochemical processes and is predominantly usedby biota on hillslopes and in small surface tributaries,seldom making it to higher order streams. Catchment runoffand hydrologic connectivity between hillslopes and streamscan vary substantially from one year to the next; questionsremain as to how storage on annual timescales affects redoxconditions and the form of exported carbon, nitrogen, andmercury.

Kotzé, ElmarieInfluence of rangeland management practises onorganic matter contents and aggregation dynamicsof clayey soils in the semi-arid grassland biome,South AfricaKotzé, Elmarie1; Sandhage-Hofmann, Alexandra2; Du Preez,Chris1; Amelung, Wulf2

1. Department of Soil, Crop and Climate Sciences,University of the Free State, Bloemfontein, South Africa

2. Institute for Crop Science and Resource Conservation,Soil Science and Soil Ecology, University of Bonn, Bonn,Germany

Rangelands cover half of the worlds land surface. In thearid to semi-arid environments of South Africa more than75% of the land is used for livestock production, and theserangelands are often subjected to degradation mainly drivenby poor land management. The grassland biome of SouthAfrica is a major resource for livestock farming, and the soilsare increasingly threatened by overgrazing. Soil organicmatter (SOM) is specifically a main factor in rangelandecosystem functioning, as it improves soil structure,enhances water infiltration and thus prevents erosion

through aggregate stabilization. Literature shows that only afew studies compared the effects of continuous androtational livestock ranching on SOM properties in semi-arid areas, and the results of these studies were mostlyinconsistent. Therefore the need was identified to researchthis topic further. The aim of this study was to investigatehow the soil properties respond to intensified rangelandmanagement under different property rights andmanagement systems. For this purpose we sampled varioustypes of rangeland management systems under communal(continuous grazing), commercial (rotational grazing) andland reform (mixture of grazing systems) farming, andwithin each of these systems we differentiated good,moderate and poor rangeland conditions along a gradient ofincreasing grazing pressure with decreasing distance to thewater points. In order to achieve this goal, soil analysesincluded the assessment of total C and N as indices oforganic matter, various plant nutrients, bulk density as wellas aggregate fractionation. Results showed that soils fromthe commercial farms exhibited higher values for especiallyC and N when compared to the other farm types. Further,the communal farms with continuous grazing were generallydepleted in all the measured nutrients. As was suspected, thedepletion increased with intensified grazing pressure, i.e.,from good to poor rangeland conditions. Along that linethere was an increased breakdown of macroaggregates withlosses of the C and N stored therein. However, thecommercial farms also exhibited a decline ofmacroaggregates and their associated C content nearby thewater points. We conclude that aggregate fractionation is asensitive indicator for detecting the beginning of soildegradation in these ecosystems; yet, degradation was lesspronounced under the rotational grazing of the commercialfarms than under communal property right conditions. Thelatter do not have fenced camps and therefore cannotpractice rotational grazing, where soils and rangelandvegetation may restore with adequate resting time.

Kumar, PraveenPassive Regulation of Soil Biogeochemical Cyclingby Root Water TransportQuijano, Juan C.1; Kumar, Praveen1; Drewry, Darren2

1. Civil and Environmental Engineering, University ofIllinois, Urbana, IL, USA

2. Jet Propulsion Laboratory, Pasadena, CA, USA

Surface and sub-surface moisture dynamics are stronglyinfluenced by the ability of vegetation to take up andredistribute soil-moisture using hydraulic redistribution(HR). These dynamics in turn affect soil biogeochemicalcycling through controls on decomposition andmineralization rates and ion transport. The goal of thisstudy is to explore this coupling between HR andbiogeochemistry using a numerical model. We examinedecomposition and mineralization of organic matter andanalyze whether differences in decomposition rates inducedby HR influence the long-term storage of carbon in the soiland the movement of nitrate (NO3-) and ammonium

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(NH4+) in the rhizosphere. These dynamics are studied in aframework that incorporates the interaction betweenmultiple plant species. The net effect of HR ondecomposition is controlled by a trade off between theresultant moisture and temperature states. This trade off isconditioned by the availability of fine roots near the surface,and it impacts the long term storage and verticaldistribution of carbon in the soil. HR also impacts thetransport and uptake of ions from the soil. It reduces theleaching of nitrate considerably, and, therefore facilitates theuptake of nitrate by vegetation roots. Furthermore, themagnitude and patterns of the feedbacks induced by HR arealso influenced by the presence of different plant speciesthat coexist. These results suggest that the alteration of soilmoisture by plants through associated processes such as HRcan have considerable impact on the below-groundbiogeochemical cycling of carbon and nitrogen. Quijano,J.C., P. Kumar, and D. Drewry, Passive Regulation of SoilBiogeochemical Cycling by Root Water Transport, To Appearin Water Resources Research, 2013, DOI:10.1002/wrcr.20310.

Kyzivat, EthanStable Water Isotope Analysis of Subsurface Flowin Artificial HillslopesKyzivat, Ethan1, 2; Nakolan, Laura3, 2; Troch, Peter A.3, 2; Smit,Yvonne4, 2; Abramson, Nathan3, 2

1. Yale University, New Haven, CT, USA2. Biosphere 2, Tucson, AZ, USA3. Hydrology and Water Resources, University of Arizona,Tucson, AZ, USA

4. Hydrology and Quantitative Water Management,Wageningen University, Wageningen, Netherlands

Stable water isotope analysis is a valuable tool inestimating water transit time, the amount of time it takesfor water to move through a hillslope or catchment and leavethe drainage basin after a precipitation event. This process isparamount to our understanding of the biogeochemical andecological effects of water fluxes on our changingenvironment. By further examining these effects, we aim toimprove water resource management, especially in semi-aridenvironments where water scarcity is common. Weincorporated isotope analysis by labeling test water withdeuterium and tracking its movement during an artificialprecipitation event at the Landscape Evolution Observatoryof the Biosphere 2. The LEO’s unique ability to control theparameters of rainfall events and its dense array of sensorsand samplers permit the careful observation of the timing ofwater moving through the hillslope. We applied threerainfall pulses to the hillslope to determine the transit timedistribution as well as the spatial and temporal variability ofwater in the hillslope. This presentation will present primaryresults of the hydrologic response of the hillslope under theprescribed conditions.

Law, Darin J.Evapotranspiration Partitioning: Competitionbetween abiotic and biotic components of thewater budgetLaw, Darin J.1; Ravi, Sujith6, 7; Barron-Gafford, Greg A.3, 2;Breshears, David D.1, 3; Huxman, Travis E.4, 5

1. School of Natural Resources and the Environment, TheUniversity of Arizona, Tucson, AZ, USA

2. Biosphere 2, The University of Arizona, Oracle, AZ, USA3. Ecology & Evolutionary Biology, The University ofArizona, Tucson, AZ, USA

4. Ecology and Evolutionary Biology, University ofCalifornia-Irvine, Irvine, CA, USA

5. Center for Environmental Biology, University ofCalifornia-Irvine, Irvine, CA, USA

6. Center for Food Security and the Environment, StanfordUniversity, Stanford, CA, USA

7. Environmental Earth System Science, StanfordUniversity, Stanford, CA, USA

Most studies focus on competition between coexistingplant species. From an ecohydrological perspective in waterlimited environments plants are also competing not onlywith the other biotic components but also with the abioticcomponents of the system in that they are trying to acquirewater for transpiration before it is lost to soil evaporation. Inan ecohydrological paradigm this evapotranspirationpartitioning is a split between “green” water and “blue”water and consequently can result in water loss beingdominated by transpiration uptake or by soil evaporativeloss. Such ET partitioning is extremely relevant for theprospects for native grass species competing with exoticgrass species in both biotic and abiotic context and thenature of such interactions could change dramatically underfuture climate conditions (warmer, drier, high vapor pressuredeficit), and even potentially resulting in plant mortality inextreme cases. Despite the fundamental importance of theissue for semi-arid grassland systems studies comparing ETpartitioning for native vs. exotic grasses under ambient andwarmer-drier climate are generally lacking. Here we showthat evapotranspiration partitioning differs dramaticallybetween a native and a coexisting exotic grass species suchthat water loss under ambient climate for the native grass isE dominated whereas for the exotic grass it is T dominated.Under warmer drier conditions, while there are shifts in thewater loss (exotic shift toward E domination native actuallyincreases T briefly), none of the plants survived theprotracted experimental dry-down in the warmer climateand the native grass died much sooner than the exotic. Theimplications of this work are three fold: (1) our resultshighlight the important role of considering ET partitioningitself, not just plant physiological response in evaluatingnative vs. exotic responses to current climate. (2) Our resultshighlight the extreme sensitivity of both natives and exoticsto mortality under drier and slightly warmer climate becausethe frequency distribution of drought duration is non-linear.Even small differences in survival time can become veryimportant under future climate conditions. (3) Most

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generally because mixed native exotic plots had responsesintermediate between native and exotic pots our resultshighlight the need to consider and integrate ET partitioningas a form of abiotic competition that determines “green” vs.“blue “water with more traditional ecological perspectivethat usually focuses solely on plant/plant competition.

Lee, JunseokTotal and soluble fluorine concentrations in soilafter occurring hydrogen fluoride spillLee, Junseok1; An, Jinsung1; Yoon, Hye-On1

1. Korea Basic Science Institute, Seoul, Republic of Korea

This study investigates the range of total fluorine (F)concentrations and soluble F fractions in soil after occurringanhydrous hydrogen fluoride (HF) spill from a chemicalplant. HF can be precipitated and then accumulated in soil,which may cause the chronic exposure of F to human viaparticle ingestion during the agricultural activities. It is clearthat the continuous monitoring of F concentration of soil inthe vicinity of accident site is necessary. Surface soil samples(n = 60) are collected and their total and soluble Fconcentrations and properties (i.e., organic matter content,total phosphorus, cation exchange capacity, soil texture) aredetermined. Correlations between the soil characteristics andboth F concentrations are investigated and the ratio ofsoluble to total F concentrations of soil is compared to thoseof previous studies. The effect of exotic F on the change ofthe readily available fraction of F in soil is discussed. Thisstudy aims to provide the information of contaminationrange and type of soil in the vicinity of the site whereaccidental HF spill occurred. Acknowledgement This studyreceived substantial support from the Geo-AdvancedInnovative Action (GAIA) project (Grant 2012000540014) ofthe Korea Environmental Industry & Technology Institute(KEITI).

Lever, RebeccaQuantifying pyrogenic carbon fluxes and meanresidence time in eroding hillslopesLever, Rebecca1; Berhe, Asmeret Asefaw1

1. University of California, Merced, Merced, CA, USA

Erosion is a ubiquitous important global process thatredistributes approximately 75 Gt of soil annually and hasbeen shown to serve as an important terrestrial carbon (C)sink. The role of soil erosion in redistribution of carbon andother essential elements has not been adequatelyinvestigated in much of the current literature. Additionally,fire plays a significant role in controlling C and pyrogeniccarbon (PyC) dynamics within the soil system. Here wepresent a new model to determine the mean residence timeof PyC by explicitly considering the role of erosionaltransport in post-fire eroding systems. The method is basedon modification of a simple first order model of soil organiccarbon dynamics that was, in the past, mainly used to modelC dynamics in static landscapes that do not experiencesignificant lateral distribution by soil erosion. With this

method we aim to demonstrate the important role thaterosion plays in lateral distribution of PyC and its estimatedmean residence time in soils of dynamic landscapes.

Lin, Hangsheng (Henry)New Frameworks for Decoding Complex SoilSystems (Invited)Lin, Hangsheng (Henry)1

1. Dept Crop Soil & Sciences, Penn State Univ, UniversityPark, PA, USA

Soils are complex systems with open boundaries,enormous heterogeneity, webs of interactions, wide-rangingscales, self-organizing features, and evolutionary changesover time. Instead of traditional reductionist approaches,three new conceptual/theoretical frameworks for decodingsoil complexity will be discussed in this presentation. First,soils are considered as so-called medium number systemswith organized complexity, where structure is an underlyingcontrol of vast heterogeneity. Such systems are qualitativelydifferent from unorganized complexity (large numbersystems, where statistical methods work) or organizedsimplicity (small number systems, where deterministicapproaches have been widely applied). Second, soilcomplexity is viewed as driven by a combination of movingand living forces, where classical moving forces has beenchampioned by the Newtonian worldview, but living forcesare creative, organizing and/or maintaining in ecosystemsthat are not necessarily in motion. Soil profiles on earth arein situ “semi-living” entities that 1) blend togetherenormous living and non-living components in complexways (without the system being moved from one place toanother) and 2) exhibit metabolic-like features fromthermodynamic and biological points of view, with featuresof self-organization and growth over time in situ. Third, aframework for unifying soil formation and soil functions issuggested, which can facilitate the linkage between theDokovchiav-Jenny’s theory of soil formation with the Darcy-Buckingham’s law of water flow in soils, whereby differenttypes of soils may exhibit contrasting flow mechanisms,pathways, and patterns.

Lybrand, RebeccaClimate and landscape position controls on soilcarbon cycling in the Santa Catalina Critical ZoneObservatoryLybrand, Rebecca1; Heckman, Katherine2; Rasmussen, Craig1

1. Soil, Water and Environmental Science Department,University of Arizona, Tucson, AZ, USA

2. Northern Research Station, USDA Forest Service,LIvermore, CA, USA

The objective of this research was to identify climate andtopographic controls on soil organic carbon (SOC) cyclingacross soils in different semiarid ecosystems. The project wasperformed within the Santa Catalina Critical ZoneObservatory in southern Arizona that spans significantrange in climate, i.e., mean annual temperature range of

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>10°C and annual precipitation range of >50 cm yr-1, with aconcomitant change in dominant ecosystem from desertscrub to mixed conifer systems. Surface (0-10 cm) andsubsurface (30-40 cm) soils were collected from graniticregolith profiles across divergent and convergent landscapepositions. Physical SOC distribution in the regolith wasquantified using a density and sonication technique toobtain the “free” (non-mineral associated), “occluded” (SOCputatively located within aggregates), and “mineral” (SOCassociated directly with mineral surfaces) C pools. Theradiocarbon data indicated that the free fractions werecomposed of the youngest SOC across all ecosystems andlandscape positions considered. Conversely, the mineral oroccluded fractions contained the oldest SOC depending onthe ecosystem. Desert scrub soils stored relatively little C(<1% SOC by weight), with all fractions dominated by fast-cycling SOC. The relatively oldest C was located in themineral fraction, indicating organo-mineral interactions asthe dominant C storage mechanism in this ecosystem. Incontrast, the conifer systems contained more SOC (>3%)with the oldest SOC found in the occluded fractionindicating an important role for aggregation as a SOCstabilization mechanism in these sites. A strong landscapeposition control on SOC distribution was also found in thissystem in that the fraction of occluded SOC was two timesthat of the divergent sites. Furthermore, the divergent soilscontained ~twice as much SOC in fast-cycling free lightfractions relative to the convergent landscape positionswhere the majority of carbon was associated with occludedand mineral fractions. The physical distribution, chemistry,and mean residence time of convergent SOC suggest alandscape level mechanism that includes the downslopetransport and burial of SOC in convergent soils. Bulk SOCat the mixed conifer convergent soil-saprolite interface (~120cm in depth) indicated a modern 14C signal (0.0‰, -16.3‰), suggesting the downward transport of dissolvedorganic carbon to this location. Indeed, 14C of dissolvedorganic carbon collected from nearby lysimeters confirmed amodern 14C signature (19.1‰, 43.5‰). The combined datasets provide the basis for understanding ecosystem andlandscape position level variation in SOC stabilization andfor constraining how shifts in climate may affect SOCstorage across this range of semiarid environments.

Ma, TaoHydrochemical constituents of interflow comparedfrom artificial experimental monoliths andcatchmentsGu, Weizu1; Ma, Tao2

1. Nanjing Institute of Hydrology and Water Resources,Nanjing, China

2. Nanjing Institute of Hydrology and Water Resources,Nanjing, China

. Groups of hydrochemical constituents of Interflowfrom artificial experimental monoliths and catchments LSwith area of 1 m2, L1 of 32 m2, and Hydrohill of 512 m2,with same kind of soil and that of rainfall show a decending

order in concentration, contrary to land surface area ofascending order. It reveals an effect of scale. An example isshown in Fig.1 The diel variations of pH and most ions ofinterflow from unsaturated zone are contrary to that ofevent rainfall. For anions, its peak concentrations happenedmostly during evening and midnight while that of cationsduring both a.m and midnight (Fig.2). If it will reveal therole of metabolism? Compare these variations with thatfrom Morningglory, an artificial catchment without soil butdebris, without saturated zone, with area of 4573 m2, can bereasoned as the role of soil. It follows that any naturalcatchment is inherently a dynamic system coupling withvarious processes in addition to the narrow hydrologicalprocess.

Fig.1 scale effect

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Fig.2 Diel variation of interflow (IF) reveals multi-coupling ofprocesses in watershed

Martin, RebeccaHydrologic Controls of DOM Export FromAgricultural Soil to Surface Water via TileDrainage: The Roles of Flow Path and ProcessingMartin, Rebecca1; Harrison, John A.1

1. School of the Environment, Washington State University,Vancouver, WA, USA

Soils are an important source of dissolved organicmatter (DOM) to surface water, and the quantity and qualityof DOM delivered to surface water can vary as hydrologicconnectivity in watersheds expands and contracts, novelsources of DOM are mobilized, and flow paths shift.Agricultural land use alters many aspects of water quality;however, controls over the quantity and quality of DOMexported from agricultural soils to surface water havereceived limited attention. This is despite evidence thatagricultural management alters soil water DOMcharacteristics and streamwater DOM chemistry at thecatchment scale. To understand the role of hydrology incontrolling the concentration and quality of DOM exportedto surface water via tile drainage, we characterized soilsolution dissolved organic carbon concentration ( [DOC] )and DOM chemical quality in a small (12 ha) agricultural

catchment in eastern Washington, and in tile drain dischargeover a three year period that included a range of hydrologicconditions. We used spectroscopic properties, includingspecific UV absorbance at 254 nm (SUVA) and fluorescenceindex (FI) to characterize DOM chemical composition. Inthis system, water that is exported via the approximately onemeter-deep tile drain has followed a flow path through boththe organic-rich surface soil and mineral subsoil, althoughresidence time in the soil column can vary greatly – on theorder of hours to months. We hypothesized that DOMwould be mobilized from the topsoil and exported withminimal processing during wet, high flow conditions whenthe hydrologic connectivity in the basin is greatest; incontrast, DOM exported during low flow conditions wouldreflect concentrations and quality observed in the sub-soil.Both the concentration and quality of DOM varied with soildepth, although variability was quite high across the field,particularly in shallow soils. In topsoil and subsoil watersamplers, [DOC] averaged 8.53 (SE 2.70) and 4.56 mg C L-1 (0.52), FI averaged 1.48 (SE 0.09) and 1.58 ( 0.01), andSUVA averaged 9.73 (13.49) and 2.34 mg C m-1 (0.19),respectively. In tile drain discharge, the concentration andchemical characteristics of DOM were correlated with tileflow rate; [DOC] ranged from 0.65 to 15.69 mg C L-1,increasing with discharge; FI decreased with discharge (range1.46 to 1.62); and SUVA increased (range 0.92 to 4.06 L mgC-1 m-1). In the winter, DOM characteristics were generallywithin the range observed in shallow and deep soil watersamples; however, in the summer [DOC] in tile draindischarge was often lower than that observed in soil water,indicating removal processes occur en route to the tile drainoutlet. These results indicate strongly contrasting effects offlow path on DOM export during hydrologically active,biologically inactive, winter conditions and hydrologicallyinactive, biologically active, summer conditions, andemphasize the need to consider both residence time andenvironmental conditions in the context of flow path tounderstand DOM transport across the terrestrial-a aquaticinterface.

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Maseyk, KadmielSoil, plant and ecosystem COS flux measurements:observations of a new tracer of the carbon cycleMaseyk, Kadmiel1; Berry, Joe2; Billesbach, Dave3; Campbell,Elliott5; Torn, Margaret4; Seibt, Ulli6, 1

1. Bioemco, Université Paris 6, Thiverval-Grignon, France2. Global Ecology, Carnegie Institution for Science,Stanford, CA, USA

3. Biological Systems Engineering, University of Nebraska,Lincoln, NE, USA

4. Earth Sciences Division, Lawrence Berkeley NationalLaboratory, Berkeley, CA, USA

5. Sierra Nevada Research Institute, University of California,Merced, CA, USA

6. Atmospheric and Oceanic Sciences, University ofCalifornia, Los Angeles, CA, USA

Atmospheric carbonyl sulfide (COS) is a promising newmeasurement-based tracer to separate soil and plant fluxesof CO2 during biosphere-atmosphere gas exchange. Theuptake of COS and CO2 by vegetation is closely coupledduring photosynthesis, providing an opportunity toestablish independent estimates of gross photosynthesis andsoil respiration at ecosystem and larger scale frommeasurements of COS and CO2 . To develop this approach,it is necessary to both establish the ratios of COS to CO2uptake from the canopy and characterise soil fluxes. We haveexplored the dynamics of COS ecosystem-atmosphereexchange in a wheat field at the Southern Great Plains usingthe latest instrumentation for trace gas research. We havemade eddy covariance (EC) measurements of ecosystem COSfluxes and automated chamber measurements of soil fluxes,providing us with unparalleled information on in situ soilCOS flux behavior. Measurements were made over a two-month period that covered the growing season, senescenceand post-harvest periods, and which yielded someunexpected results. We found that during the growingseason, there was a strong uptake of COS by the canopy ofbetween ~ 10 and 40 pmol m-2 s-1, with a strong diel signal.Ecosystem COS sink strength diminished as the plantsapproached the grainfilling period, and after senescence andover the harvested field, we observed a strong source of COSto the atmosphere of up to +40 pmol m-2 s-1. Contrary towhat is commonly assumed, we observed that overall the soilwas a net source of COS, but both sink and source behaviourwas observed in a strongly temperature dependent response.Further investigations into the soil COS fluxes indicate thatroots, not soil microbes, appear to be responsible for theCOS production, and hypothesise that processes associatedwith senescence and plant internal reallocation of resourcesunderlie the interesting seasonal pattern of COS fluxes weobserved. We have also made measurements in aMediterranean oak system, including unique data on theCOS to CO2 uptake ratio during photosynthesis under fieldconditions. These results reveal that this ratio is notconstant in time but show diurnal and synoptic scalevariability that appears largely environmentally. We alsoobserved a temperature dependence of soil COS fluxes that

was similar to that observed in the wheat field at lowertemperatures, but with a stronger dependence on soil watercontent. Ongoing measurements that will also be presentedinclude ecosystem and component fluxes in a freshwatermarsh ecosystem. This information is necessary forparameterising regional scale modelling and interpretationof boundary layer atmospheric COS concentrationmeasurements. Overall, these high-resolution COSmeasurements at high precision are opening up newopportunities for exploring and constraining carbon cycleprocesses.

McDonnell, Jeffrey J.The importance of boundary conditions on waterflow and residence time at the hillslope scale(Invited)McDonnell, Jeffrey J.1

1. Global Institute for Water Security, University ofSaskatchewan, Saskatoon, SK, Canada

The effects of boundary conditions on flow andtransport at the hillslope scale are poorly understood.Formative experiments in the field in the 1960s controlledboundary conditions when examining flow and transport bycovering the soil surface and removing vegetation and/orlining the soil base with concrete or similar impermeablematerial. Results from these studies still define ourconceptual framework for streamflow generation at thecatchment scale. Here I re-examine some of these benchmarkworks and interpretations in light of new results focused onboundary controls at the hillslope scale. Two examples arepresented: one focused on upper soil boundary (atmosphere-vegetation partitioning) and the other focused on the lowerboundary (the soil bedrock interface). These results showthat boundary conditions are perhaps the defining featureof water movement at the hillslope (and catchment) scaleand that partitioning at these interfaces influences most, theage, origin and pathways of water movement from the soilsurface to the stream. I illustrate these effects with examplesfrom hillslopes in the USA Pacific Northwest and Mexicoand show how these boundary controls also have potentialramifications for related issues of slope stability, surface-groundwater interactions and water quality.

McKenna, Owen P.Geomorphic controls over Nitrogen and CarbonStocks in Desert PlayasMcKenna, Owen P.1; Sala, Osvaldo E.1

1. School of Life Sciences, Arizona State University, Tempe,AZ, USA

Playas are ephemeral desert wetlands situated at thebottom of closed catchments. Desert playas in theSouthwestern US have not been intensively studied despitetheir potential importance for the functioning of desertecosystems. The objective of this study is to assessgeomorphic and ecological variables that control carbon andnitrogen stocks in playas. We hypothesize that the

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magnitude of carbon and nitrogen stocks depend on: (a)catchment size, (b) catchment slope, (c) catchment biomass,(d) catchment plant cover and (e) spatial arrangement (e.g.patch size distribution), and (f) catchment soil texture. Wechose thirty playas from across the Jornada Basin (LasCruces, NM) ranging from 0.005-0.60 km2 in area and withvarying catchment characteristics. We used a 5m digitalelevation map (DEM) to calculate the catchment size andcatchment slope for these thirty playas. We measuredbiomass, percent cover, and patch size using the point-intercept method with three 10m transects in eachcatchment. We used the Bouyoucos-hydrometer soil particleanalysis to determine catchment soil texture. Stocks oforganic carbon and nitrogen were measured from soilsamples at four depths (0-10 cm, 10-30 cm, 30-60 cm, 60-100cm) using C/N combustion analysis. Using a 5m DEM wecalculated the catchment sizes of the thirty playas, theseranged from 0.10-26.99 km2. We used the same data tocalculate the slope of each catchment, these range from0.015-0.21 m elevation/ 5m distance. In terms of nitrogenand carbon storage, we found soil nitrogen values rangingfrom 0.007-0.114 %, and soil carbon values ranging from0.002-1.36 %. The results of a regression analysis show bothnitrogen and carbon decrease linearly as a function of soildepth (nitrogen: y= -0.015x+0.071, R2=0.30; carbon: y= -0.19x+0.89, R2=0.24). The results of an additional regressionanalysis show a positive relationship between catchment sizeand nutrient stock size (% of soil sample) for both nitrogenand carbon (nitrogen: y= 7.0*10-5x +0.027, R2=0.14; carbon:y= 0.0014x + 0.29, R2= 0.25). These data support ourhypothesis that catchment size is one of factors controllingcarbon and nitrogen stock in desert playas.

Moosavi, SadredinUse of a Selective Inhibitor Technique RevealsControls on Hidden CH4 Biogeochemical CyclingAlong Soil Moisture Gradients From Wetland toUpland in Boreal & Arctic SoilsMoosavi, Sadredin1

1. Science, RCTC, Rochester, MN, USA

Use of a selective inhibitor technique for observation ofsoil carbon trace gas fluxes measured along moisturegradients can offer insight into biogeochemical processeshidden from net emission measurements collected by fluxchamber or remote sensing approaches. Net emissions fromwetland systems almost universally indicate theseenvironments are major methane (CH4) sources whileupland systems appear to be small CH4 sinks. Use of theselective inhibitor methyl fluoride (CH3F) reveals a morecomplicated scenario in which methanogens andmethanotrophs respond differentially to both long andshort-term changes in soil conditions. Dry, upland soils richin organic matter appear to have a latent potential tobecome, at a minimum, short-term CH4 sources whenexposed to precipitation events. The extant methanotrophicpopulation, accustomed to the limited CH4 supply availablefrom the atmosphere may be limited in its ability to respond

to this spike should the increased moisture conditionsfavoring methanogenesis persist. Similarly, the large sourceof CH4 from organic-rich wetland soils masks a significantcomponent lost to CH4 oxidation in a narrow zone at thetop of the water table. While CH4 production appearspossible over a broad range of the soil profile from thosecomponents which remain flooded, measurements in soilcores suggest that the methanotrophic populationresponsible for amelioration of CH4 emission to theatmosphere resides in the soil layer where the water table istypically found and does not quickly track water tablemovements outside this band. Deviations in the elevation ofthe water table caused by extreme weather events or climaticchange, either directly due to changes in precipitation andevapotranspiration or indirectly via changes in the level ofsurface waters, thus have the potential to disrupt the balancebetween CH4 production and consumption triggeringunexpectedly large changes in methane flux to theatmosphere. The scale and duration of such changes acrossthe landscape remains to be identified. Given that CH4oxidation consumes from 10-25% in arctic systems, 40-60%in boreal systems and as much as 90% in subtropical ricepaddies, this potential feedback to weather events resultingfrom climate change should not be ignored. Fieldexperiments along moisture gradients from open water toupland systems in boreal and arctic soils will be examinedalong with results from 50 cm deep peat cores from borealsoils exposed to changes in the water table in microcosm.

Nguyen, MichaelProbing Temperature-Dependent Organo-FeOxInteractions Using Quartz Crystal Microgravimetry,NMR Spectroscopy, and Thermal AnalysesNguyen, Michael1; Hockaday, William1; Lau, Boris1

1. Dept. of Geology, Baylor University, Waco, TX, USA

Soils are becoming increasingly important in climatechange discussions. Soil respiration accounts for the secondlargest flux of carbon dioxide globally. It is unknownwhether warming will turn the soil reservoir into a carbonsource or alter its ability to act as a sink. One mechanism bywhich soil organic carbon is stored is through the formationof organo-mineral complexes. 50-75% of all natural organicmatter (NOM) in soils has been found associated withmineral surfaces. These org-min interactions can protectcarbon from decomposition for timescales of decades tomillennia. This study utilizes spectroscopic, thermal, andsurface-sensitive techniques to examine the formation aswell as the physical and chemical changes in org-mincomplexes caused by climate-relevant temperature changes(25, 30, 35°C). Iron oxide (Fe2O3) was chosen as therepresentative soil mineral substrate. Soil humic and fulvicacids purchased from the International Humic SubstancesSociety were chosen as the representative NOM. Nuclearmagnetic resonance spectroscopy (1H NMR) was used toidentify the interacting functional groups. Our initial resultssuggest that aromatic (phenolic) components of NOMpreferentially interact with Fe2O3. Thermogravimetric

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analysis (TGA) is being used to determine thethermostability of org-min complexes. Differential scanningcalorimetry (DSC) is being utilized to measure thethermodynamics and binding energies associated with org-min complexes. Quartz crystal microgravimetry is beingused to quantify the extent and kinetics ofadsorption/desorption between NOM and mineralsubstrates. Preliminary QCM experiments conducted withAl2O3 and soil humic acid suggest that 1) NOM adsorptionfollows Langmuir kinetics, 2) the extent of adsorption at 25,30, and 35°C are not significantly different, and 3) the initialrate of adsorption was only significantly different at 35°C.TGA, DSC, and QCM experiments are currently beingconducted with Fe2O3 and soil humic acid. The results ofthis study will help to predict how soils dominated by ironrich minerals will respond to increasing temperatures.

Niu, Guo-YueA Microbial Enzyme Based Soil Organic Carbon(SOC) Decomposition Model for Use in ClimateModelsNiu, Guo-Yue3, 1; Zhang, Xia2; Barron-Gafford, Greg A.4, 1

1. Biosphere 2, The University of Arizona, Tucson, AZ, USA2. Institute of Atmospheric Physics, Chinese Academy ofSciences, Beijing, China

3. Department of Hydrology and Water Resources, theUniversity of Arizona, Tucson, AZ, USA

4. School of Geography and Development, the University ofArizona, Tucson, AZ, USA

The scheme of SOC decomposition in most climatemodels is based on the first-order decay, and the dependenceof the decay rate on temperature is based on a Q10relationship (e,g, Q10=2.0, meaning the decay rate increases2 times for every 10 K increase in temperature). However, thisscheme is inconsistent with current understanding ofdecomposition mechanisms. SOC decomposition shoulddepend on the activity of microbial communities andtemperature sensitivity is more complex depending onacclimation of the carbon use efficiency by microbes. Wepresent a microbial enzyme based SOC decompositionmodel. In the model up to five pools of soil carbon aredefined including SOC, dissolved organic carbon (DOC),microbial biomass carbon (MIC), and enzyme (ENZ). Themodel assumes enzyme-catalyzed degradation of organiccompounds and to simulate the pulse response to rainfall(or the “Birch effect”) DOC is further divided into two poolsincluding a bio-available pool that allows catalyzed C toaccumulate during dry periods for later use by microbes inwet periods. This model has been successfully tested againstsoil CO2 efflux and NEE collected in a natural savannahecosystem at the Santa Rita of the AmeriFlux network.

Niu, Guo-YueAnalysis of an extreme rainfall-runoff event at theLandscape Evolution Observatory by means of athree-dimensional physically-based hydrologicmodelNiu, Guo-Yue2, 1; Pasetto, Damiano3; Scudeler, Carlotta3;Paniconi, Claudio3; Putti, Mario4; Troch, Peter2, 1

1. Biosphere 2, The University of Arizona, Tucson, AZ, USA2. Department of Hydrology and Water Resources, theUniversity of Arizona, Tucson, AZ, USA

3. Institut National de la Recherche Scientifique, CentreEau Terre Environnement (INRS-ETE),, Université duQuébec, Quebec City, QC, Canada

4. Department of Mathematics, University of Padova,Padova, Italy

We present a detailed analysis, by means of a three-dimensional physically-based hydrological model, of the firstexperiment conducted at the Biosphere 2 LandscapeEvolution Observatory (LEO). The experiment was driven byan intense rainfall event and produced a hydrologicalresponse characterized by predominant water outflow alongthe lower lateral boundary of LEO (seepage face), togetherwith overland flow that began 15 hours after the start ofrainfall and that caused erosion of the superficial soil andformation of a small channel. In the first simulations, usingsoil parameters estimated from an analysis of particle sizedistribution (e.g., porosity s = 0.39 m3 m–3) and varyingsaturated hydraulic conductivity (Ks), the model did notproduce any overland flow. In subsequent simulations,reducing either s or Ks at the seepage face (Ks,sf) facilitatedoverland flow production. To systematically search for theoptimal parameters, we then performed over 10,000sensitivity simulations by varying Ks, s, and Ks,sf for twovalues of the n parameter in the van Genuchten soilhydraulic characteristics (n = 2.26 and n = 1.72, obtained byfitting the van Genuchthen relationship measured at LEOand in laboratory, respectively). It was found thatsimulations with Ks,sf < Ks produced a higher probability ofbest realizations than those with Ks,sf = Ks for both valuesof n. In addition, the best realizations for both n values withKs,sf < Ks result in smaller errors than those with Ks,sf = Ks.The simulation results are consistent with our in-situobservations that the seepage face, consisting of gravels anda perforated plate, became partially filled with fine soilparticles transported and deposited by saturated subsurfaceflow. The optimized n (2.26) and Ks (1.110–4 m s–1) valuesfor LEO are higher than those from laboratorymeasurements with the same soil (n = 1.72 and Ks = 2.010–5m s–1), suggesting a possible “scale” effect.

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Ogee, JeromeGlobal estimates of land photosynthesis inferredfrom the global budget of 18O in atmosphericCO2: the crucial role of soil microorganisms(Invited)Ogee, Jerome1; Wingate, Lisa1; Cuntz, Matthias2

1. INRA, Villenave d’Ornon, France2. Helmholtz Centre for Environmental Research, Leipzig,Germany

Quantifying terrestrial carbon storage and predictingthe sensitivity of ecosystems to climate change relies on ourability to obtain observational constraints on photosynthesisand respiration at large scales (ecosystem, regional andglobal). Photosynthesis (GPP), the largest CO2 flux from theland surface, is currently estimated with considerableuncertainty (1-3). Robust estimates of global GPP can beobtained from an atmospheric budget of the oxygen isotopiccomposition (18O) of atmospheric CO2, provided that wehave a good knowledge of the 18O signatures of theterrestrial CO2 fluxes (1, 4). The latter reflect the

18O of leafand soil water pools because CO2 exchanges “isotopically”with water [CO2+H2

18OÄH2O+CO18O]. This exchange can

be accelerated by the enzyme carbonic anhydrase (CA). Inleaves, where CA is present and abundant, this isotopicequilibrium is reached almost instantaneously. As aconsequence, and because soil and leaf water pools havedifferent 18O signatures, CO2 fluxes from leaves and soilscarry very distinct 18O signals and can thus be tracked fromthe fluctuations in the 18O of atmospheric CO2 (a). Theaccelerated isotopic exchange between CO2 and water due toCA activity has recently been shown to be a widespreadphenomenon in soils as well (4). Across a range ofecosystems, we found that CO2 hydration was 10 to 1000times faster than the un-catalysed rate, with highest valuesin the hottest ecosystems. At the global scale, accounting forsoil CA activity dramatically shifts the influence of soil andleaf fluxes on a, thus changing the estimates of terrestrialgross CO2 fluxes. In this talk we will present the currentstate of understanding of the environmental and ecologicalcauses behind the variability in CA activity observed in soilsand illustrate how this variability can influence ourestimates of global GPP inferred from a budgets. References1. L. R. Welp et al., Interannual variability in the oxygenisotopes of atmospheric CO2 driven by El Niño, Nature 477,579–582 (2011). 2. C. Beer et al., Terrestrial Gross CarbonDioxide Uptake: Global Distribution and Covariation withClimate, Science 329, 834–838 (2010). 3. C. Frankenberg etal., New global observations of the terrestrial carbon cyclefrom GOSAT: Patterns of plant fluorescence with grossprimary productivity, Geophys. Res. Lett. 38 (2011),doi:10.1029/2011GL048738. 4. L. Wingate et al., The impactof soil microorganisms on the global budget of 18O inatmospheric CO2, Proceedings of the National Academy ofSciences 106, 22411–22415 (2009).

Ou, LingCarbon sequestration of Louisiana crawfish pondssedimentOu, Ling1; Wood, C. W.1; Boyd, Claude E.1; McClain, W. R.2;Shaw, Joey1

1. Auburn University, Auburn, AL, USA2. LSU Agcenter, Rayne, LA, USA

Carbon (C) sequestration is considered an effectivemethod to mitigate climate change and improve soil quality.Many studies have examined agricultural soils for theirability to sequester, but few studies have investigated Caccumulation in sediments under aquaculture. In Louisiana,crawfish farming has grown to include more than 1,200farms occupying more than 50,000 ha of land. This studyexamined C sequestration in crawfish aquaculture pondsediments. The study compared SOC (soil organic C)amounts under crawfish ponds and adjacent agriculturefields. There were two crawfish farming systems:monocropping and crop rotation. Soils depths sampled were0-5, 5-10, 10-15 and 15-20 cm. A significant difference(P<0.05) was found in the top layer for SOC concentration incrawfish monocropping systems (25.8 g kg-1) compared toadjacent crop fields (20.8 g kg-1). However, no significantdifferences were found in other soil/sediment layers for Cconcentration or C mass. Crawfish ponds do not appear tohave an advantage over upland cropping systems with regardto soil C sequestration. In addition, according to pond depthand pond age with SOC correlation, input and output of C,a possible C equilibrium in aquaculture ponds, managementpractices and effects of SOC on pond quality andproduction, C sequestration of Louisiana crawfish ponds orother aquaculture ponds is not promising.

Pachepsky, YakovModeling Flow and Transport in Field Soil withPedotransfer and ScalingPachepsky, Yakov1; Yakirevich, Alexander M.2; Guber, AndreyK.3; Gish, Timothy J.1; Cady, Ralph E.4; Nicholson, ThomasJ.4

1. BARC, USDA-ARS, Beltsville, MD, USA2. Department of Environmental Hydrology &Microbiology, Ben-Gurion University of the Negev, SedeBoqer, Israel

3. Department of Plant, Soil and Microbial Sciences,Michigan State University, East Lansing, MI, USA

4. ORR, US NRC, Rockville, MD, USA

Scale dependence in soil flow and transport parametershas been demonstrated by using measurement techniqueswith different support volumes. Pedotransfer functions toestimate soil hydraulic conductivity from soil texture andbulk density were developed from data of measurements onrelatively small samples. Simulations of flow and transportin field soils may involve using coarse grids andcorresponding large computational cells. We tested thehypothesis that upscaling saturated hydraulic conductivityfrom the small sample support volume to the support

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volume of large computational cells can provide usefulestimates of this critical parameter for numericalsimulations of flow and transport using large computationcells. We tested this hypothesis with groundwater and soluteconcentration monitoring data from field scale tracerexperiment in which chloride tracer was introduced in soilwith the pulse of irrigation water and the irrigationcontinued for four months causing predominantly lateraltracer transport in variably saturated soil and groundwater.The power law upscaling of pedotransfer-predicted hydraulicconductivities resulted in the model accuracy comparablewith the accuracy of the calibrated model. Support size-based scaling of saturated hydraulic conductivity appears tobe useful in finding the effective hydraulic conductivity ofcomputational cells in soils within the two-orders ofmagnitude linear scale range.

Pal, DavidDetermining Relationships Between DissolvedHydrogen and Methane Porewater Concentrationsand Static Chamber Flux Measurements inVegetated Wetland SoilsPal, David1; Tripathee, Rajan2; Shäfer, Karina V.2; Jaffe, PeterR.1

1. Civil and Environmental Engineering, PrincetonUniversity, Princeton, NJ, USA

2. Biological Sciences, Rutgers University, Newark, NJ, USA

Methanogenesis and wetland methane emissions havebeen studied for multiple decades, repeatedly demonstratingthe importance of methane and wetlands to global climatechange. Acetate, hydrogen and carbon dioxide are significantsubstrates for methane production. Studies have shown thatalmost one third of all methane produced in wetland soils isproduced by the hydrogen-dependent methanogenesispathway. While hydrogen is a precursor to methaneproduction in soils, few studies have examined subsurfacehydrogen dynamics and gas exchange in wetland soils.Methane emissions are primarily controlled by volatilizationthrough plants and this loss pathway may also prove to be asignificant loss mechanism for hydrogen in soils. It isimportant to be able to quantify hydrogen losses fromwetland soils in order to more accurately understandmethane substrate availability and production rates. Ourobjective is to better understand the relationship betweenhydrogen, atmospheric methane flux and porewaterconcentrations and explore how this relationship may have acontrol on methanogenesis in soils. In this study we presentdissolved methane and hydrogen data from subsurface“peeper” measurements and the related above-ground staticchamber flux measurements from tidal Spartina spp. andPhragmites australis soils. “Peepers” are subsurface dialysis-based porewater sampling devices that allow for themeasurement of dissolved gas profiles, and other dissolvedchemicals, in saturated, vegetated or unvegetated, sediments.Static chambers measure fluxes through the same vegetationand soil types as the “peepers” to understand how vegetationand soils affect gas emission rates. By combining “peeper”

measurements with static chamber flux measurements wecan understand how methane and hydrogen volatilizationrates are affected by subsurface gas concentration profiles inthe upper and lower soils. Additionally, by studying methaneand hydrogen simultaneously, we can demonstrate therelative importance of hydrogen volatilization rates as acontrol for methane production and any relationshipsbetween methane and hydrogen flux. In order to betterconceptualize vertical methane profiles we can evaluate gasloss and volatilization models along with porewatersubstrate availability as controls on methanogenesis indiscretized mathematical models.

Pangle, Luke A.Climate-warming impacts on water and carbonfluxes in a seasonally semi-arid grasslandecosystemPangle, Luke A.1; Phillips, Claire L.2; Gregg, Jillian W.3;McDonnell, Jeffrey J.4

1. Water Resources Graduate Program, Oregon StateUniversity, Corvallis, OR, USA

2. Crop and Soil Sciences, Oregon State University,Corvallis, OR, USA

3. Terrestrial Ecosystems Research Associates, Corvallis, OR,USA

4. School of Environment and Sustainability, University ofSaskatchewan, Saskatoon, SK, Canada

A challenge in ecohydrological research is to understandhow interactions between climate, vegetation function, andsoil-moisture dynamics control intra- and inter-annualvariation in hydrologic partitioning and carbon fluxes inspecific environments. We present results from theTerracosm experiment—a manipulative climate changeexperiment in western Oregon, USA—that examined theresponses of evapotranspiration, soil moisture, potentialgroundwater recharge, and net-ecosystem carbon exchangein response to an experimental temperature increase of 3.5degrees Celsius that was applied symmetrically throughoutthe day, and asymmetrically such that daily minimumtemperatures increased more than daily maximumtemperatures. The results were strongly influenced by theseasonal trends of precipitation and temperature, plantfunction, and resulting soil moisture dynamics. Warmertemperatures enhanced evapotranspiration during thespring, which was driven by greater vapor-pressure deficitand accelerated timing of peak-seasonal photosyntheticrates, and contributed to earlier drawdown of soil-waterstorage entering the summer drought period. A negativefeedback mechanism resulted, whereby evapotranspirationduring the summer was actually lower under climate-warming treatments than under ambient temperature, dueto earlier onset of plant senescence and water-limitedevaporation. Despite warming-enhanced evapotranspirationduring the spring, potential groundwater recharge wasmostly unaffected in this Mediterranean climate whereprecipitation and temperature are temporally out of phase.In addition to accelerating the timing of peak-

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photosynthetic rates during the spring, warming treatmentsenhanced annual-gross photosynthesis, but ultimatelyshifted the grasslands towards a more carbon-negativecondition due to proportionally greater enhancements ofecosystem respiration. This unique manipulative experimentrevealed the important linkages between precipitation,temperature, plant function and soil moisture thatcontrolled how critical-zone water and carbon fluxesresponded to projected temperature increases associatedwith global climate change.www.teraglobalchange.org;

people.oregonstate.edu/~pangle

Pardo, Linda H.A hydropedological approach to identifyingsources and sinks of nitrogen in a steep, headwatercatchment using nitrogen and oxygen isotopesPardo, Linda H.1; Bailey, Scott W.2; Green, Mark B.3

1. USDA Forest Service, Burlington, VT, USA2. Northern Research Station, US Forest Service, NorthWoodstock, NH, USA

3. Plymouth Statue University, Plymouth, NH, USA

Spatial heterogeneity in soil hinders scaling up fromindividual measurements to the catchment scale. Recentadvances in understanding of the complex relationshipbetween soil development and hydrology have facilitated thedevelopment of a novel way to classify soils intohydropedological units (HPU) at the Hubbard BrookExperimental Forest, N.H. The HPUs represent arrangementof soils along hillslope catenas. Typical podzols form undervertical percolation while E-podzols, Bhs-podzols, and Bhpodzols are influenced by lateral development processes inpositions that develop transient watertables. Bimodalpodzols represent a transition between typical and Bhpodzols. Aquepts are found in seeps with permanently highwater tables. . The HPUs also vary in extent and nature ofcarbon (C) and nitrogen (N) cycling. In particular, E-podzolsand Bhs-podzols tend to have the highest levels of nitrateand dissolved organic carbon (DOC) in soil solution andgroundwater. In order to evaluate C and N cycling patternsand improve our understanding of sources and sinks of Cand N, we measured NO3

-, NH4+, DON, DOC, 15N-NO3

-,18O- NO3

-, and pH in soil lysimeters, groundwater wells,and streams during events of different magnitude and type.As higher 18O- NO3

- are associated with atmosphericdeposition, we expected that 18O in nitrate would decreasealong flowpaths as residence time in the catchmentincreased and would increase with duration of event asstored solution was flushed from the system. We expectedthat for HPUs that are paired (one upslope, one downslope),the downslope HPU would reflect less input from depositionand processing of N mediated by soil, but found thisdifference to vary with HPU. Preliminary 18O- NO3

- dataranged from -7 to +26‰ with a broader range for TropicalStorm Sandy (Aug 2012) than for samples collected at theend of snowmelt (April 2013). Similarly, 15N-NO3

-, whichranged from -13 to +7‰, had a much broader range during

the large summer storm event than for the late snowmeltsamples. The HPU classification holds considerable promiseboth for improving predictions of C and N loss or retentionand for scaling up to the catchment or landscape scale in thenorthern forest of the U.S.

Pasetto, DamianoSoil water potential assimilation to reconstructsaturated hydraulic conductivity at the LandscapeEvolution ObservatoryPasetto, Damiano1, 2; Niu, Guo-Yue3, 4; Paniconi, Claudio1;Putti, Mario2; Troch, Peter A.4

1. Centre Eau Terre Environnement, Institut National de laRecherche Scientifique, Quebec City, QC, Canada

2. Dept of Mathematics, University of Padua, Padua, Italy3. Biosphere 2 - Earth Science, University of Arizona,Tucson, AZ, USA

4. Dept of Hydrology and Water Resources, University ofArizona, Tucson, AZ, USA

The Biosphere 2 Landscape Evolution Observatory(LEO) has been developed to investigate hydrological,chemical, biological, and geological processes in a large-scaleand controlled infrastructure. The experimental hillslopes atLEO are instrumented with a large number of differentsensors (water potential, water level, soil moisture, etc) thatallow detailed monitoring of local dynamics and changes inthe hydrological state and structure of the landscapes, suchas the development of soil heterogeneity. Sensor failure insuch an evolving system can have a dramatic impact onobservability of flow dynamics and estimation of soilproperties with a numerical model. In this study we assessthe ability to retrieve the saturated hydraulic conductivity ofthe soil under scenarios of heterogeneity (different values ofcorrelation length) and varying degrees of sensor failure. Theanalysis is conducted by way of numerical simulations usingthe physically-based hydrological model CATHY to emulatethe flow experiment. The Ensemble Kalman filter techniquepermits us to assimilate the measured data into thenumerical simulation and in so doing estimate/correct boththe state and parameters of the model. We consider asynthetic scenario that reproduces the first hydrologicalexperiment at LEO (22 h of rainfall at ~12 mm h–1). Weassume that the ‘true’ hydraulic conductivity is a particularrandom realization of a stochastic field with lognormaldistribution and exponential correlation length. During the‘true’ run, we collect water potential measurements (usingDecagon dielectric sensors) at an hourly interval. Theperturbed observations are then used in the assimilationprocess to retrieve the spatial values of the conductivity. Theresults show, for instance, that there is only a slightdeterioration in the solution of the inverse problem whenthe full configuration (496 sensors) is reduced to 360 and132 sensors.

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Peterson, FoxForest Composition links Soil SOM and DOC toANPP in Complex TerrainPeterson, Fox1, 2; Lajtha, Kate2

1. Forestry, Oregon State University, Corvallis, OR, USA2. Crop and Soil Science, Oregon State University, Corvallis,OR, USA

As permitted by Henry Vereecken, I will submit myabstract by 6-22; I have family matters to attend to. Pleaseread this abstract from our recent article submitted to JGRBiogeosciences for an idea of what we will present: Factorsinfluencing soil organic matter (SOM) stabilization anddissolved organic carbon (DOC) content in complex terrain,where vegetation, climate, and topography vary over thescale of a few meters, are not well understood. We examinedthe spatial correlations of LiDAR and GIS derivedtopography, measured soil characteristics, and vegetationcomposition and structure versus SOM fractions and DOCpools and leaching on a small catchment (WS1) in the H.J.Andrews Experimental Forest, located in the westernCascades Range of Oregon, USA. We predicted thataboveground net primary productivity (ANPP), litter fall,and nitrogen (N) mineralization would be positivelycorrelated with SOM, DOC, and carbon (C) content of thesoil. We also predicted that site characteristics that increasedC inputs would increase C stores and losses in the soil. Whilewe found that ANPP was correlated with litter fall (increasedC inputs) and DOC export, we did not find the expectedrelationships between ANPP, litter fall, SOM stores per unitarea, C content of the soil, or DOC pools. Similarly, soil rockcontent was not well correlated with ANPP, SOM pools, orDOC export, and only demonstrated decreases at very high(> 30%) percentages of rocks in the upper 50 cm. However,exposed, dry sites had lower SOM stores and content andDOC stores and export than moist wet sites. We concludethat many factors, such as stand history, plant adaptation todrought, and even soil erosion in complex terrain canobscure expected patterns between carbon storage in soilsand plant productivity.

Phillips, Claire L.Using Radiocarbon to Investigate Soil RespirationImpacts on Atmospheric CO2Phillips, Claire L.1, 2; LaFranchi, Brian W.2; McFarlane, KarisJ.2; Desai, Ankur R.3

1. Crops and Soil Science, Oregon State University,Corvallis, OR, USA

2. Center for Accelerator Mass Spectrometry, LawrenceLivermore National Lab, Livermore, CA, USA

3. Oceanic and Atmospheric Science, University ofWisconsin, Madison, WI, USA

While soil respiration is believed to represent the largestsingle source of CO2 emissions on a global scale, there arefew tools available to measure soil emissions at large spatialscales. We investigated whether radiocarbon (14C)abundance in CO2 could be used detect and characterize soil

emissions in the atmosphere, taking advantage of the factthat 14C abundance in soil carbon is elevated compared tothe background atmosphere, due to the legacy onthermonuclear weapons testing (i.e. bomb-C). Working in atemperature hardwood forest system in Northern Wisconsinduring 2011-12, we made semi-high-frequencymeasurements of CO2 at nested spatial scales from the soilsubsurface to 150 m above ground level. Thesemeasurements were used to investigate seasonal patterns inrespired C sources, and to evaluate whether variability insoil-respired 14C could also be detected in atmosphericmeasurements. In our ground-level measurements we foundlarge seasonal variation in soil-respired 14CO2 thatcorrelated with soil moisture, and was likely related to rootactivity. Atmospheric measurements of 14CO2 in the forestcanopy (2 to 30m) were used to construct Keeling plots, andthese provided larger spatial-scale estimates of respired14CO2 that largely agreed with the soil-level measurements.In collaboration with the NOAA we also examined temporalpatterns of 14CO2 at the Park Falls tall-tower (150m), andfound elevated 14CO2 levels during summer months thatwere likely due to increased respiration from heterotrophicsources. These results demonstrated that a fingerprint fromsoil-respired CO2 can be detected in the seasonal patterns ofatmospheric 14CO2, even at a regionally-integrating spatialscale far from the soil surface.

Powell, Katherine M.Links between soil water availability and soilrespiration in semi-arid ecosystems along theColorado Front RangePowell, Katherine M.1, 2; Anderson, Dean E.2; Blanken, PeterD.3

1. Environmental Studies, University of Colorado, Boulder,CO, USA

2. U.S. Geological Survey, Denver, CO, USA3. Geography, University of Colorado, Boulder, CO, USA

Arid and semi-arid regions represent a large fraction ofthe world’s terrestrial ecosystems, and as water-limitedenvironments, they are sensitive to changes in soil watercontent which may result in large carbon efflux from soils inresponse to precipitation events. Previous research hasdemonstrated that soil temperature and soil water contentare the primary controls on soil respiration (Rs), however fewstudies relate soil water potential to Rs, although it may be abetter metric for representing how water is available to soilmicrobes and vegetation. Therefore, resolving how episodicchanges in soil water content, specifically measures of waterpotential, cause arid/semi-arid ecosystems to shift from acarbon sink to a source is important for improving futureestimates of terrestrial ecosystem fluxes in these areas. Ourstudy focuses on above and belowground fluxes of carbondioxide and water at two grassland sites and one montaneforest site in Colorado. Continuous (hourly) soil CO2concentration profile measurements, at 5cm, 10cm and20cm (15cm in the grasslands) are coupled with continuous(30 minute), collocated soil water content and soil

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temperature (Ts) measurements. Soil water availability isdetermined by using tensiometers at each site to relatievolumetric water content to matric potential values. Toquantify belowground heterogeneity, soil samples werecollected from each site to determine texture (by sieves andsettling columns) and organic matter content (by loss onignition). All of the sites have ongoing eddy covariance-basedsurface measurements of water, carbon and energy fluxes,including net ecosystem exchange (NEE). To estimate Rs atthe surface, discrete fluxes of CO2 are measured with aportable photosynthesis system (chamber) and a soil “gassnake”(Heinemeyer et al. 2012) - a flexible tube withopenings along the bottom, connected to a gas analyzer, thatlies on the soil surface around the base of the vegetation. Tocharacterize changes in aboveground biomass, vegetationsamples are routinely collected from each of the sites andleaf area index (LAI) and dry biomass are determined.Measurements of Rs, soil water content, soil water potential,precipitation, Ts will be summarized on daily, monthly,seasonal, and annual timescales for each site. Time-seriesplots of Rs will be compared with aboveground fluxes ofcarbon as well as soil water, Ts, precipitation, air temperature(Ta), photosynthetically active radiation (PAR), humidity,evapotranspiration (ET), and LAI. Preliminary results showsoil CO2 concentration increases were well correlated withsoil water content increases at the same soil depth followingprecipitation events and infiltration. More measurementsand calculations will be required to determine monthly andseasonal responses and to make further comparisons withaboveground fluxes and biomass changes.

Prentice, SamuelQUANTIFYING HILLSOPE SOIL THICKNESSUSING FINE SCALE TERRAIN MODELLINGPrentice, Samuel1

1. Geography, University of California, Santa Barbara, CA,USA

Digital elevation models (DEMs) are the dominantinput to spatially explicit digital soil mapping (DSM) effortsdue to their increasing availability and the tight couplingbetween topography and soil variability. Accuratecharacterization of this coupling is dependent on DEMspatial resolution and soil sampling density, both of whichmay limit analyses. For example, DEM resolution may be toocoarse to accurately reflect scale-dependent soil propertiesyet downscaling introduces artifactual uncertainty unrelatedto deterministic or stochastic soil processes. We tackle theselimitations through a DSM effort that couples moderatelyhigh density soil sampling with a very fine scale terrestriallidar dataset (20 cm) implemented in a semiarid rollinghillslope domain where terrain variables change rapidly butsmoothly over short distances. Our guiding hypothesis isthat in this diffusion-dominated landscape, soil thickness isreadily predicted by continuous terrain attributes coupledwith soil catena hillslope segmentation. We choose soilthickness as our keystone dependent variable for itsgeomorphic and hydrologic significance, and its tendency to

be a primary input to synthetic ecosystem models. Indefining catenary hillslope position we adapt a logical rule-set approach that parses common terrain derivatives ofcurvature and specific catchment area into discrete landformelements (LE). Variograms and curvature-area plots are usedto distill domain-scale terrain thresholds from short rangeorder noise characteristic of very fine-scale spatial data. Therevealed spatial thresholds are used to condition LE rule-setinputs, rendering a catenary LE map that leverages therobustness of fine-scale terrain data to create a generalizedinterpretation of soil geomorphic domains. Preliminaryregressions show that continuous terrain variables alone(curvature, specific catchment area) only partially explainsoil thickness, and only in a subset of soils. For example,curvature explains 40% of soil thickness variance at <300 cmat scales up to 20 m, while soil thickness >300 cm shows noclear relation to curvature. Further efforts will be aimed atrefining the regression model by integrating the spatially-constrained generalized LE map classes, as well as simulatingDEM error for uncertainty analysis.

Presler, Jennifer K.Chemical Signatures of Biological Colonization in aModel EcosystemPresler, Jennifer K.1; Zaharescu, Dragos1; Burghelea,Carmen1; Dontsova, Katerina1; Chorover, Jon2; Maier,Raina2; Huxman, Travis3

1. Biosphere-2, University of Arizona, Tucson, AZ, USA2. Soil, Water, and Environmental Science, University ofArizona, Tucson, AZ, USA

3. School of Biological Sciences, University of California,Irvine, Irvine, CA, USA

Ecosystem formation relies on interactions betweenbiotic and abiotic factors to stabilize a habitat, create soil,and make favorable conditions for plants and animals. Anoligotrophic ecosystem can form as plants and microbesextract exploitable elements from a substrate otherwise poorin available nutrients, e.g. rock. In order to understand howdifferent components of plant -microbes- -fungalcommunities interact with bedrock to create soil and form aprimordial ecosystem, a modular experiment was designedat Biosphere-2. The experiment involves 4 granular rocks, i.e.basalt, granite, rhyolite and schist, and biologicalcombinations of rock microbes, plants (Bouteloadactyloides, grass and Pinus ponderosa, pine), and associatedmycorrhizae: arbuscula mycorrhiza - Glomus intraradicesand ectomycorrhiza - Rhizopogon evadens. A plant-free, un-inoculated control was also included. Columns wereirrigated with nanopure water and monthly samples of waterrunoff were collected and analyzed for water consumption,pH, conductivity, dissolved organic and inorganic C, total N,major nutrient and trace element leaching and uptake. Herewe present data from the first 4 months of the experiment.The biological treatments affected porewater chemistrydifferently for each rock. pH slightly decreased in all rocksand treatments over time, while ecosystem colonizationsignificantly lowered pH with respect to control for basalt

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and rhyolite, and raised it on schist. Electrical conductivity, ameasure of total element dissolution, was positivelycorrelated with increased ecosystem complexity for all rocksexcept schist, where it decreased. Treatments dissociatedwith time. Significant chemical signatures of ecosysteminteraction with bedrock were discovered through analysis ofporewater elements. Inorganic carbon (IC), a measure ofbelow ground biomass respiration, had increased productionin the planted components on all bedrocks except schist.This appeared to show a seasonal trend, with clearseparation between the vegetated and un-vegetatedtreatments over time. However, there was a uniquedependence of IC on pH for schist, suggesting a strong pHinfluence on below-ground processes on this rock. Also onthis rock, the presence of grass mycorrhiza had a significanteffect on dissolved organic carbon compounds. Conversely,pine mycorrhiza had the opposite effect on basalt.Phosphorus, an essential nutrient for growth, energy andDNA production seemed to have been less available ongranite and schist as indicated by a comparatively lower lossunder biological treatment. While on basalt pine mycorhizadecreased P loss, grass mycorrhiza on rhyolite had anopposite effect. Our results showed that element leachingdepends strongly on treatment and rock type. For example,phosphorus…the sentence from up. The study exemplifiesthat there is a high variability in terms of element releaseand uptake on different bedrock under ecosystemcolonization and mycorrhiza plays an important role in thisvariability.http://www.b2science.org/earth/people/res/dontsova/ge

obiology

Rasmussen, CraigUsing statistical methods to quantify and predictcatchment scale soil variabilityRasmussen, Craig1; Holleran, Molly1

1. Soil, Water and Env. Science, University of Arizona,Tucson, AZ, USA

Quantifying catchment scale regolith physicochemicalvariation has the potential to yield important insights to theevolution and function of the subsurface critical zone. Theobjective of this study was to quantify and predict soilproperties within a forested catchment in southern AZ, USA.The catchment, Marshall Gulch (MG), is part of the JemezRiver Basin-Santa Catalina Mountains Critical ZoneObservatory (CZO). MG is 5-hectare, mixed-conifer forestedcatchment situated on granitic parent material, with a meanelevation of 2400m, mean annual temperature of 10°C andmean annual precipitation of 75 cm. The study was designedusing a combination of principle component analysis (PCA)of available geospatial data and a conditioned LatinHypercube Sampling (cLHS) scheme. Geospatial datadetermined by the PCA to account for 95% of landscapevariance included modeled soil depth, slope, soil wetnessindex, normalized difference vegetation index (NDVI), andNational Agriculture Imagery Program (NAIP) bands 3/2.The cLHS scheme was performed using these geospatial data

and determined 20 optimal sample locations for collectingsoil material down dug to the depth of refusal, and sampledaccording to genetic horizon. Soils were characterized usingmethods of X-ray Fluorescence (XRF), X-ray Diffraction(XRD), particle size, color, pH, electrical conductivity (EC),C/N isotopes, and loss on ignition (LOI). Regression modelspredicting soil depth (cm), carbon (kg m-2), clay (%), Na flux(kg m-2), pH, and volumetric strain were developed using the20 sample locations, the six geospatial data layersdetermined from the PCA, and reverse step-wise multiplelinear regression. Results indicated strong correlations ofsoil properties with the drainage systems in the MGcatchment. Deeper soils, higher clay content, higher carboncontent, and greater Na loss were observed and modeledwithin the drainages of the catchment relative to adjacentslopes and ridgelines. Regression R2 values ranged from 0.35(soil depth, cm) to 0.50 (carbon, kg m-2) and all modelsexhibited p-values <0.05. Regression model residuals wereextrapolated spatially using an optimized Inverse DistanceWeighting (IDWopt), followed by cross validation anddetermination of spatial autocorrelation using Moran’s I.Cross validation mean errors approached zero and residualerrors were randomly distributed throughout the catchmentas determined by Moran’s I, indicating unbiased modelswith no spatial autocorrelation in predicted residuals.Spatial maps of prediction residuals were added to soilproperties predicted with the regression models to yield finalinterpolated maps of profile data at the scale of the entirecatchment. Overall we found soil properties variedpredictably with topography and landscape positionthroughout the catchment, yielding strong correlations tothe convergent drainages within the study site. These dataprovide a clear basis for modeling water, carbon, andsediment transport within the catchment, in addition tolaying the foundation for quantifying catchment scale soil-water and carbon storage capacities.

Reichstein, MarkusSoil, climate extremes and the carbon cycle(Invited)Reichstein, Markus1

1. Department for Biogeochemical Model-Data Integration,Max-Planck-Inst. for Biogeo., Jena, Germany

In this presentation I will highlight the importance ofthe soil for global biogeochemical questions and pose thequestion, whether the complexity of the soil is adequatelyconsidered in global biogeochemical analysis and modeling.Vertical heterogeneity and vegetation-soil feedback, the roleof soil (micro-)biota in the carbon cycle and bio-chemicaland physico-chemical limitations of soil processes will bediscussed as important topic in this context. Moreover Iargue that the soil is an important determinant of howecosystems and their biogeochemical cycle respond toclimate extremes, which have recently attracted attention forcarbon cycle impact. Finally as synthesis I will present globalresidence times of ecosystem carbon, confront these with

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modeling results and discuss the difference in light of theabove consideration.

Reid, Matthew C.Gas Exchange in the Wetland Rhizosphere:Quantifying Spatial and Temporal Variability atField Scales with Dissolved Gas Tracer ExperimentsReid, Matthew C.1; Pal, David S.1; Jaffe, Peter R.1

1. Civil and Environmental Engineering, PrincetonUniversity, Princeton, NJ, USA

Wetlands exist at the interface of terrestrial and aquaticsystems, and their anaerobic soils are biogeochemical “hotspots” for element cycling that produces trace gases ofenvironmental importance including methane (CH4),nitrous oxide, and halomethanes. The balance betweenbiochemical production and uptake in soils depends, in part,on mass transfer to other compartments of the environment.Chemical transport along the soil – plant – atmospheresystem is an important pathway for these biogenic gases andcontrols mass fluxes from sediments to the atmosphere, butis highly heterogeneous in space and time and remainspoorly described in ecosystem-scale budgets. Plant gastransport is governed by uptake processes at root surfaces,but quantitative information on uptake kinetics is limited bythe lack of non-invasive techniques to monitor rhizosphereprocesses. The objective of this study is to improvepredictions of gas fluxes through vegetation by integratingin-situ measurements of rhizosphere gas exchange withscaling strategies based on root and vegetation communitydistributions. Here we describe the first field application of adissolved gas tracer push-pull test (PPT) to make in-situkinetics measurements of dissolved gas root uptake in thewetland rhizosphere. PPTs involve the injection of a solutioncontaining dissolved sulfur hexafluoride, helium, andbromide tracers into saturated wetland sediments andsubsequent sample withdrawal from the same injectionpoint. Tracer ratios in the extracted solution were combinedwith analytical advection-dispersion-reaction models todetermine first-order uptake rate coefficients. Measurementswere conducted across several months and in differentvegetation zones of a New Jersey tidal marsh to assessseasonal and spatial variations in soil – root gas exchangerates. Tracer-derived rate coefficients were combined withroot and vegetation distributions to scale vegetation-mediated gas exchange estimates to the patch scale, and werevalidated against a set of CH4 porewater and fluxmeasurements. Measurements revealed order-of-magnitudedifferences in dissolved gas root uptake rates betweenseasons, marsh vegetation zones, and soil column depths.Rate coefficients scaled to CH4 approximated measuredfluxes, providing a process explanation for CH4 transportthrough plants. These experiments yield new andquantitative insights into the fate and transport of tracegases in wetland soils, and provide a more completeunderstanding of the biogeochemical processes central tothe ecosystem services provided by wetlands.

Root, Robert A.Toxic metal(loid) speciation is controlled by ironmineral (bio)weathering in phytostabilized minetailingsRoot, Robert A.1; Hammond, Corin1; Valentin, Alexis1;Herbertson, Linnea1; Maier, Raina M.1; Chorover, Jon1

1. SWES, University of Arizona, Tucson, AZ, USA

Legacy mine tailing sites in (semi-)arid environmentspresent a significant health risk to nearby communities fromoff-site wind and water transport of (toxic) metal-ladenparticles. Compost-aided phytostabilization, for revegetationof mine wastes, has been employed as an in situ strategy toreduce contaminant dispersion and diminish physicalerosion. The changes in microbial composition andmetal(loid) speciation that accompany the requisite additionof water and organic matter into the desert tailings remainpoorly known and this motivates our work. Field, mesocosm,and laboratory studies revealed that rhizosphere microbiotaexperienced a 5-log increase in bacterial 16S rRNA copynumber in the amended compared to control tailings and anattendant transition from sulfidic minerals to ferric(oxy)hydroxide and jarosite type minerals with concomitantsequestration of As in the solid phase. We conclude that thedisequilibrium imposed by phytostabilization results in anaccretion of heterotrophic biomass that is concurrent with atime series of geochemical transformations, which controlsthe species, fate, and bioavailability of toxic metal(loid)sincluding Zn, As, and Pb.

Green house and field-scale compost-aided phytostabilization forrevegetation of mine tailings.

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Roy Chowdhury, TaniyaRole of Geochemical and Microbially DrivenProcesses in Carbon Dynamics in Arctic EcosystemsRoy Chowdhury, Taniya1; Graham, David1; Tang, Guoping2;Chourey, Karuna3; Hettich, Robert3; Phelps, Tommy1; Elias,Dwayne1; Wullschleger, Stan2

1. Biological Sciences, Oak Ridge National Laboratory, OakRidge, TN, USA

2. Environmental Sciences, Oak Ridge National Laboratory,Oak Ridge, TN, USA

3. Chemical Sciences, Oak Ridge National Laboratory, OakRidge, TN, USA

Permafrost-affected soils occupy only 16% of the earth’ssurface but store nearly 50% of the terrestrial global C. Theorganic matter in these systems will be subjected toincreased microbial degradation as the active layer deepensand permafrost thaws and remains unfrozen for extendedperiods due to soil warming. The unique nature of thesefrozen materials, consisting of organic, mineral, and mixedorganic/mineral materials, as well as saturated seasonallythawed active layers and permafrost layers with massive,pore, and vein ice, makes the ideal assessment oftemperature response of C fluxes very challenging. In turn,the proportion of greenhouse gases like methane (CH4) andcarbon dioxide (CO2) released in response to soil warmingdepend on the microbial response to warming, organicmatter availability and the geochemistry. This study aims atunderstanding the underlying feedback processes betweensoil geochemistry and microbial activity towards anenhanced understanding of Arctic systems. Intact frozen soilcores were collected from the Center, Ridge and Troughareas of a low-centered polygon on the BarrowEnvironmental Observatory (Barrow, Alaska). A typical soilcore consisted of a 0-20 cm deep organic (O) horizon, 20–50cm deep mineral (B) horizon and 50–90 cm deep permafrost.Significant amounts of ferrous iron in O and B horizonsconstituting the active layer and permafrost indicatedanaerobic soil chemistry. Therefore, microcosms wereconstructed to incubate soils using ecologically relevanttemperatures of -2, +4 or +8 °C under anaerobic conditions.Both CH4 and CO2 production exhibited distincttemperature response curves. To estimate the dependence oforganic C degradation on electron acceptor concentrations,the data were fit to predictive models. CO2 productioncould be explained by Monod kinetics exhibiting a shorterlag phase in contrast to CH4 production that followedexponential kinetics, with a longer lag phase characteristic ofphysiological adaptation. Production rates for both CH4 andCO2 were substantially higher in microcosms of O horizon(~40 % total C) at all temperatures, compared to B horizonsamples (~20 % C) or permafrost (~12 % C) that producedCO2 but negligible CH4. Metaproteomincs revealedabundance of signature proteins from methanogens andiron storage in the biomass extracted from untreated frozensoils in both permafrost and active-layer. Followingincubations, however, methanogenic proteins were foundonly in active-layer samples, consistent with the temperature

induced headspace gas measurements. This suggests thatthawing and warming of the low-centered polygon soilpotentially increases microbial biomass with associatedsignificant changes in microbial community structure.Additionally, microbial biomass production, fermentation,iron reduction and methanogenesis potentially explain mostof the C and electron flow in these closed systems. Themicrocosm incubation studies presented herein provide astarting point for mechanistic understanding of C fluxes infuture climate in the Arctic.

Sadro, StevenThe influence landscape position and catchmentcharacteristics on the biogeochemistry of high-elevation lake-chainsSadro, Steven1, 2; Nelson, Craig E.2

1. Earth Research Institute, University of California SantaBarbara, Santa Barbara, CA, USA

2. Ecology, Evolution, and Marine Biology, University ofCalifornia, Santa Barbara, Santa Barbara, CA, USA

In catchments where lakes are connected in a sequentiallake-stream network, or lake-chain, terrestrial loading andaquatic processing simultaneously take place alongdownstream flow paths. While the concentrations of solutesare generally thought to increase with increasing pathlength, it is less clear how biogeochemically reactivematerials such as nutrients and dissolved organic mattermay change. Furthermore, the extent to which landscapeposition, catchment characteristics, or hydrologicalconnectivity affect material processing remains largelyunexplored. To examine these dynamics, we conducted asurvey of high-elevation lake-chains from 14 differentcatchments in the Sierra Nevada (California). We sampled atotal of 76 lakes and the stream segments connecting themto evaluate spatial patterns within and among lake-chainsfor a wide range of biogeochemical variables. In addition totaking a snapshot of concentrations under baseflowconditions, we explored material processing by taking thedifference between inlet and outlet samples of lakes ordownstream and upstream samples for stream reaches. Thesedata help illustrate controls over material transport andtransformation within lake and stream networks ofheadwater catchments. There were distinct spatial patternsto the characteristics of dissolved organic matter (DOM) inhigh-elevation Sierran lakes. Dissolved organic carbon(DOC) concentration was related to a number of landscapecharacteristics, most notably to slope and the extent ofvegetation cover within catchments. Landscape influence onDOM was strongest during spring snowmelt when DOC washighest and the fluorescence index, a relative measure ofallochthonous and autochthonous fulvic acids in thedissolved organic matter pool, indicated organic matter waslargely of terrestrial origin. There were strong gradients indissolved nitrogen species along downstream flowpathsdelineated by changes in rock and shrub cover. Nitratetended to decline and dissolved organic nitrogen (DON) toincrease linearly across the alpine zone where shrub cover

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increased to ~20-25% and rock cover decreased to ~70%.Landscape patterns in bacterioplankton abundancemirrored these downstream increases in DOM. Patterns ofmaterial processing within lakes and streams were morecomplex. Lakes tended to be sources for Chlorophyll-a andbacterioplankton cells, exporting them to stream reacheswhere their concentrations tended to decline alongdownstream flowpaths. However, nutrient and organicmatter processing was much more variable, with some lakesand streams acting as sources and others as sinks. Whilelandscape position or catchment characteristics accountedfor some of this behavior, the majority of the variabilityremained unexplained. Despite the relative lack of coherencein material processing, our results emphasize that manybiogeochemically reactive variables changed predictablyalong gradients in catchment characteristics or withlandscape position.

Sandeep, KizhurSoil-Sediment Linkages in the Catchment area ofLakes in Southern IndiaSandeep, Kizhur1, 2; Shankar, Rajasekhariah1; Warrier, AnishK.1, 3

1. Department of Marine Geology, Mangalore University,Mangalore, India

2. Department of Geology, Government College Kasaragod,Kasaragod, India

3. National Centre for Antarctic & Ocean Research, Vasco-da-Gama, India

We investigated the rock magnetic properties (lf, fd,ARM and IRM’s at different field strengths) of sedimentcores from five lakes (Pookot Lake (PK),Thimmannanayakanakere (TK), Shantisagara (SS),Ayyanakere (AK) and Kurburkere (KK)) as well as surface andsub-surface soil samples from the respective catchment areasof the lakes in southern India. The principal objectives of thestudy were to understand pedogenesis in tropical regionsand establish soil-lake sediment linkages, which will beuseful in paleoclimatic studies of lake sediments. The studyrevealed the absence of lithogenic/anthropogenic magneticgrains, bacterial magnetite and greigite in soil and sedimentsamples. Seasonal studies of the soil samples showed thatthe time lag between pedogenic magnetite formation andtopsoil erosion is negligible. The PK profile, which receiveshigh rainfall (~ 4000 mm/year), does not exhibit anymagnetic enhancement of topsoil. There is hardly anydifference between the magnetic susceptibility (lf) values ofsurface and sub-surface samples, which reflects the deeplyweathered nature of the soil profile. The SS profile exhibitslessivage of magnetic minerals, resulting in a thickmagnetically enhanced zone. It displays the highest lfvalues among the five profiles studied. The TK and AK soilprofiles do not exhibit any magnetic enhancement. In fact,lf values increase towards the profile-bottom, suggestingtop-soil erosion, besides contribution of magnetic mineralsfrom parent rocks. In the TK profile, there is a cleardistinction between surface and sub-surface samples, the

former being magnetically coarse grained. The KK profileexhibits moderate to strong lf values and a mild magneticenhancement at the surface. The pedogenic magnetiteformed in the lake catchment is transported and depositedon the lake-bed during each monsoon season, recording andpreserving the climatic signal of that year. The magneticsusceptibility record of sediment cores from the five lakesprovide the Holocene climatic history of the region. High lfvalues indicate periods of high rainfall and vice versa. Theclimate varied significantly during the Holocene and thetrend of variation was not similar across the five sites. Theorganic carbon and nitrogen contents derived fromhydrophytes and terrestrial plant detritus also variedsignificantly, depending upon the climatic conditions. TheC/N ratio of organic matter was used to differentiatebetween organic matter derived from aquatic algae/planktonand land plants. There is a high correlation between organiccarbon and nitrogen (r=0.93), indicating that both theelements are organically bound. The low C/N ratios indicatedeep lake conditions because of the abundant planktonicgrowth, implying a warm and wet climate and vice versa.

Sanderman, JonathanLinking soils and streams: production,consumption, transformation and export ofdissolved organic matter in two contrastingwatersheds (Invited)Sanderman, Jonathan1; Lohse, Kathleen A.2; Baldock, JeffreyA.1; Amundson, Ronald3

1. Division of Land and Water, CSIRO, Glen Osmond, SA,Australia

2. Biological Sciences, Idaho State University, Pocatello, ID,USA

3. Environmental Science, Policy and Management,University of California, Berkeley, CA, USA

In headwater streams, the concentration and reactivityof dissolved organic matter (DOM) primarily reflect thecombined influence of terrestrial biogeochemical cycling oforganic matter and the hydrologic routing of water throughthe landscape. In this talk, I will present isotopic (13C and14C) and spectroscopic (UV and 13C nuclear magneticresonance) data from two contrasting first-order watershedsin coastal California to demonstrate the importance of bothsoil biogeochemical processes and hydrologic connectivity incontrolling stream water DOM concentration, age andreactivity. Soil pore water DOM is regulated by the interplaybetween biological productivity and organic matter supply,exchange reactions with the soil matrix, and microbialutilization [Sanderman et al., 2008]. In particular, exchangereactions between the solid and dissolved phase wereimportant in regulating pore water DOM chemistry. Despitedifferences in the distribution of OM stocks and litterchemistry, similar shifts in DOM chemistry were observedwith soil depth at both sites. In a moderate relief mixedgrassland watershed (3.9 ha), hydrometric observationsindicated that runoff generation shifted from throughflowto shallow macropore flow to overland flow during large

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winter storms. At base flow, only old and highly processeddeep soil OM and DOM sources were connected to thestream, resulting in low concentrations of old and highlyaltered DOM in stream water; whereas when saturatedoverland flow dominated during storms, a direct connectionbetween surface and shallow DOM-rich source areas and thestream resulted in high concentrations of younger andfresher DOM in stream water. In this hydrologically dynamicsystem, stream DOM composition exhibited a temporallyvariable composition representative of almost the entirerange in organic chemistry as found within the soil itself[Sanderman et al., 2009]. In a higher relief redwood-Douglasfir dominated watershed (16 ha), a very narrow range ofstream DOM concentration and chemistry was found acrossstream flows spanning three orders of magnitude. Here, anetwork of large subsurface soil pipes limited the buildup ofpore pressures and thus limited the extent of shallowsaturated areas contributing to stream flow. Due to the lackof shallow flow contributing to runoff, DOMconcentrations were consistently low with a characteristicchemistry of highly altered deep soil OM. Within the soil,biogeochemical transformations greatly alter the characterof DOM as water percolates through the soil but thehydrologic connectivity between the soil and the streamappears to be the dominant control on stream water DOMcomposition in headwater streams. References: Sanderman J,Baldock JA, Amundson R (2008) Dissolved organic carbonchemistry and dynamics in contrasting forest and grasslandsoils. Biogeochemistry 89: 181-198 Sanderman J, Lohse KA,Baldock JA, Amundson (2009) Linking soils and streams:Sources and chemistry of dissolved organic matter in a smallcoastal watershed. Water Resources Research 45: W03418

Schaaf, WolfgangUsing the constructed catchment Chicken Creek todisentangle feedbacks between soils, surfacestructures, vegetation and hydrology during initialecosystem developmentSchaaf, Wolfgang1; Elmer, Michael2; Gerwin, Werner2;Zaplata, Markus K.2

1. Soil Protection, BTU Cottbus, Cottbus, Germany2. Research Centre Landscape Development and MiningLandscapes, BTU Cottbus, Cottbus, Germany

Over a period of eight years, we investigated the initialdevelopment of the constructed catchment Chicken Creek,south of Cottbus, Germany (Gerwin et al., 2009). Since theboundary conditions and inner structures of the hillslopeare well known and documented (Gerwin et al., 2011), thesite offers unique possibilities to study the relevant processesof ecosystem development interacting with variousstructures and patterns. We observed considerable changeswithin the catchment (Elmer et al., 2013). Both internal andexternal factors could be identified as driving forces for theformation of structures and patterns in the artificialcatchment. Initial structures formed by the constructionprocess and initial substrate characteristics were decisive forthe distribution and flow of water. External factors like

episodic events triggered erosion and dissection during thisinitial phase, promoted by the low vegetation cover and theunconsolidated sandy substrate (Schaaf et al., 2013). Withtime, secondary structures and patterns evolved and becamemore and more important. Invading biota and vegetationsuccession initialized feedback mechanisms resulting inpattern and habitat formation, and generally in increaseddifferentiation, heterogeneity and complexity that are typicalcharacteristics of ecosystems (Schaaf et al., 2011). Theprocesses and feedback mechanisms in the initialdevelopment of a new landscape may deviate in rates,intensity, and dominance from those known from matureecosystems. It is therefore crucial to understand these earlyphases of ecosystem development and to disentangle theincreasingly complex interactions between the evolvingterrestrial and aquatic, biotic, and abiotic compartments ofthe system. Elmer M, Gerwin W, Schaaf W, Zaplata MK,Hohberg K, Nenov R, Bens O, Hüttl RF (2013): Dynamics ofinitial ecosystem development at the artificial catchmentChicken Creek, Lusatia, Germany. Environ Earth Sci 69, 491-505. Gerwin W, Schaaf W, Biemelt D, Fischer A, Winter S,Hüttl RF (2009): The artificial catchment “Chicken Creek”(Lusatia, Germany) - A landscape laboratory forinterdisciplinary studies of initial ecosystem development,Ecol Eng 35, 1786-1796. Gerwin W, Schaaf W, Biemelt D,Winter S, Fischer A, Veste M, Hüttl RF (2011): Overview andfirst results of ecological monitoring at the artificialwatershed Chicken Creek (Germany). Phys Chem Earth 36,61-73. Schaaf W, Bens O, Fischer A, Gerke HH, Gerwin W,Grünewald U, Holländer HM, Kögel-Knabner I, Mutz M,Schloter M, Schulin R, Veste M, Winter S, Hüttl, RF (2011):Patterns and processes of initial terrestrial ecosystemdevelopment. J Plant Nutr Soil Sci 174, 229-239. Schaaf W,Elmer M, Fischer A, Gerwin W, Nenov R, Pretsch H, Seifert S,Winter S, Zaplata MK (2013): Monitoring the formation ofstructures and patterns during initial development of anartificial catchment. Environ Monit Assess 185, 5965-5986.

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Schmidt, MichaelGeochemical tools to infer charring temperature,aromaticity and the degree of condensation of fire-derived organic matter in soil, water, and sediment- a method comparisonSchmidt, Michael1; Wiedemeier, Daniel B.1; Abiven, Samuel1;Hockaday, William C.2; Keiluweit, Marco3; Kleber, Markus3;Pyle, Lacey A.4; Masiello, Caroline A.4; McBeath, Anna V.5;Nico, Peter S.6; Schneider, Maximilian P.1; Smernik, RonaldJ.5

1. Department of Geography, University of Zurich, Zurich,Switzerland

2. Geology Department, Baylor University, Waco, TX, USA3. Department of Crop and Soil Sciences, Oregon StateUniversity, Corvallis, OR, USA

4. Department of Earth Sciences, Rice University, Houston,TX, USA

5. School of Agriculture, Food and WIne, University ofAdelaide, Adelaide, SA, Australia

6. Earth Science Division, Lawrence Berkeley NationalLaboratory, Berkeley, CA, USA

Fire-derived, pyrogenic carbon (PyC) is a persistentorganic carbon fraction with a slow turnover in theenvironment because it is relatively resistant againstchemical and biological degradation. It thus represents animportant carbon fraction with a sequestration potential inthe global carbon cycle. PyC is naturally produced on a largescale during wildfires and anthropogenically in the form ofbiochar, when organic waste is pyrolyzed. Aromaticity andthe degree of condensation are the two main qualityproperties of PyC that probably largely determine itspersistence against degradation. The two parameters shouldtheoretically be dependent on pyrolysis conditions, such ascharring temperature, pyrolysis time or feedstock. In thisstudy, we used four different feedstocks and two differentpyrolysis procedures to produce a thermosequence of 40chars, ranging from 100 – 1000° C. The chars were thenanalyzed with six different state-of-the-art methods: solidstate 13C nuclear magnetic resonance (13C NMR), diffuseinfrared Fourier transform spectroscopy (DRIFT), X-raydiffraction (XRD), synchrotron-based near-edge X-rayabsorption fine structure analysis (NEXAFS), benzenepolycarboxylic acid analysis (BPCA) and pycnometry. Theyallowed to infer the aromaticity and the degree ofcondensation of the material. Using multivariate statisticalmethods, aromaticity and the degree of condensation couldsuccessfully be linked to charring temperature becausecharacteristic patterns of the two properties could beobserved by different methods throughout the wholethermosequence. Moreover, we show, which methods aremost suitable for a quality assessment of PyC and discusstheir advantages and limitations.

Scudeler, CarlottaNumerical simulations of isotope tracerexperiments at the Landscape EvolutionObservatoryScudeler, Carlotta1, 2; Niu, Guo-Yue3, 4; Paniconi, Claudio1;Putti, Mario2; Troch, Peter3, 4

1. INRS-ETE, Quebec city, QC, Canada2. Department of Mathematics, University of Padova,Padova, Italy

3. Biosphere 2 – Earth Science, The University of Arizona,Tucson, AZ, USA

4. Department of Hydrology and Water Resources, TheUniversity of Arizona, Tucson, AZ, USA

The Biosphere 2 Landscape Evolution Observatory(LEO) is a research infrastructure designed to study andquantify different hillslope processes, some of them relatedto subsurface flow and solute transport. It consists of threeidentical sloping convergent landscapes inside anenvironmentally controlled facility at Biosphere 2, theUniversity of Arizona. The hillslopes are instrumented with adense network of sensors and samplers for detailedmeasurement of subsurface flow, water potential, soilmoisture, and tracer concentrations. Tracers can beintroduced into the system at a constant or time-varying ratevia the rainfall simulator that has been engineered to deliverwater at a rate between 0.003 and 0.045 m/h. In this studywe used deuterium to label water that entered one of thelandscapes at known rate and concentration. The analysesare performed with a physically-based hydrological modelthat solves Richards’ equation for water flow and theadvection-dispersion equation for solute transport. Thesimulations are used for interpretation of the observationdata, such as what is the impact of the unsaturated zone andthe initial hillslope water storage on the amount of tracermeasured at the seepage outlet? Is there evidence thatgeochemical reactions are altering the expected mass balanceof the system? and for assessment of the numericalperformance of the model, such as what is the sensitivity of astandard finite element discretization to spatio-temporalresolution and different types of boundary condition? Whatare the accuracy gains – especially in terms of mass balance –in using more advanced algorithms for velocity calculationand solute propagation?

Seyfried, Mark S.Soil Temperature and Water Dynamics onContrasting Aspects in the Rain-Snow TransitionZone at Reynolds CreekSeyfried, Mark S.1; Bryden, Sage2; Link, Timothy2

1. US Dept Agr ARS, Boise, ID, USA2. University of Idaho, Moscow, ID, USA

Understanding how complex terrain effects hydrologicaland biogeochemical processes has become increasinglyimportant as the global climate changes because we need toknow how water and carbon fluxes are integrated across the

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landscape up to relatively large (i.e., regional) domains. Soilsmodulate both fluxes and are therefore central to thisunderstanding. Spatial variations of incoming solarradiation, which are a primary driver of terrain effects, arewell understood and quantified. Although terrain effects onsoils are well documented in a qualitative fashion, very littlequantitative description has been done. We are particularlyinterested in soil temperature and water content becausethey exert strong controls on both water and biogeochemicalfluxes. We measured soil water () and temperature (Ts)profiles at three paired locations in mountainous, complexterrain in SW Idaho, USA (~43°latitude). Each pairconsisted of a soil profile of temperature and water contentfrom a depth of 5 cm to bedrock (50 to 110 cm) on opposingnorth and south facing slopes at the same elevation. Theseprofiles are co-located with meteorological stations(including snow depth) and precipitation and streamfloware measured nearby. The sites are located near therain/snow transition elevation for the area (1600 m) on steepslopes (25 to 40°) with sparse vegetative cover. Soils onnorth facing slopes are deeper with greater organic matteraccumulation but otherwise less profile development. Weexpected to measure large Ts contrasts during summer, whensolar radiation is greatest and heat accumulates in the soiland that differences would subside and possibly reverseduring the winter, when differential snow cover wouldinsulate north facing soils more than the south facing soils.We measured dramatic differences between the two slopes,with a difference of 9°C (at 50 cm) in August. Differencesbetween slopes were smaller in winter, about 4° C, but didnot reverse. For perspective, the Ts difference between twoopposing slopes at identical elevations that we measured ispractically the same as the difference between Ts measuredon nearly level ground but separated by 1000 m in elevation.Due to the measured temperature differences, greater year-round carbon mineralization and respiration and greaterground heat flux to the surface are expected from south-facing soils. We expected on north facing soils to declinemore slowly and later in the year the south facing soilsbecause the evaporative demand is greater on south facingslopes. We did not observe this and, in fact, on the twoslopes responded similarly during spring and early summer.This is attributed to two factors. First, spring rains weresufficient to maintain relatively high soil water storage onboth slopes. Second, the denser vegetative cover on thenorth-facing slopes counters the lesser evaporative demand.We are further quantifying these findings via process-basedmodeling.

Seyfried, MarkReynolds Creek Carbon Critical Zone Observatory:Improving prediction of soil carbon storage andflux from the pedon to the landscape scaleLohse, Kathleen A.1; Seyfried, Mark2; Benner, Shawn4; Glenn,Nancy3; Flores, Alejandro4; Baxter, Colden1; Crosby,Benjamin3; de Graaff, Marie-Anne5; Feris, Kevin5; Finney,Bruce1; Flerchinger, Gerald2; Godsey, Sarah3; McNamara,James4; Marks, Danny2; Pierce, Jennifer4; Reinhardt, Keith1

1. Biological Sciences, Idaho State University, Pocatello, ID,USA

2. USDA ARS, Northwest Watershed Research Center, Boise,ID, USA

3. Geosciences, Idaho State University, Pocatello, ID, USA4. Geoscience, Boise State University, Boise, ID, USA5. Biological Sciences, Boise State University, Boise, ID, USA

Most of the world’s terrestrial carbon is found in thecritical zone, where it is predominantly stored as soil carbon.This important carbon reservoir is sensitive to climatic andland use change and may act as a source or sink foratmospheric carbon dioxide. Despite its importance, soilcarbon remains a critical source of uncertainty in bothcarbon cycling and global climate models. That uncertaintyarises due to both an incomplete understanding of theprocesses dictating soil carbon fate and the challenge of up-scaling often highly spatially and temporally heterogeneoussoil processes to the landscape or global level. The ReynoldsCreek Carbon Critical Zone Observatory (RCC CZO) willaddress the grand challenge of improving prediction of soilcarbon storage and flux from the pedon to the landscapescale. Reynolds Creek Experimental Watershed is particularlywell suited for this effort because it extends over stronggradients in climate and vegetation with associated dramaticdifferences in both soil organic and inorganic carbon. Thesegradients facilitate both observation-based science andexperimental investigations in which the gradients act asprimary variables. This new CZO will also be supported byunique long-term, spatially- extensive, meteorological, soilmonitoring, and atmospheric datasets that will both informand constrain conceptual and numerical models of soilcarbon behavior. Research efforts will be focused along aseries of intensively instrumented (eddy flux towers, soilrespiration, moisture, temperature, and a suite of climaticmonitoring) sites along the elevation gradient. Extensivecharacterization of above and below ground biomass, soilcarbon amounts, distribution and characteristics will beundertaken at these sites as well as in a distributed manneracross the watershed, producing a massive watershed-scaledataset that can inform soil carbon research for generations.Experimental research will include long-term manipulationsof precipitation regime and fire (chronosequence)investigations. Modeling of soil physical, chemical andbiological processes will inform our efforts to revealmechanistic linkages between soil carbon behavior and keyenvironmental variables. Sophisticated climate-hydrologicmodels will be used to spatially distribute those controllingvariables at a sufficiently high resolution (5 m) to capture

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the natural heterogeneity on the landscape. This data willallow application of ecosystem-soil carbon simulations thatcan be tested against the landscape-scale datasets and usedto inform our understanding of soil carbon behavior anddirect our research activities towards the areas of greatestuncertainty.

Stewart, Ryan D.Improved understanding and prediction of runoffthresholdsStewart, Ryan D.1; Rupp, David E.2; Abou Najm, Majdi R.3;Selker, John S.1

1. Biological & Ecological Eng, Oregon State University,Corvallis, OR, USA

2. Oregon Climate Change Research Institute, College ofEarth, Ocean and Atmospheric Sciences, Oregon StateUniversity, Corvallis, OR, USA

3. Civil & Environmental Engineering, American Universityof Beirut, Beirut, Lebanon

Clay soils with shrink-swell characteristics – called verticsoils - are found all over the world. The formation ofshrinkage cracks profoundly affects the hydrology of thesesoils, making it difficult to accurately understand and modelprocesses such as infiltration, preferential flow, and runoff.Data collected from a set of instrumented runoff plotslocated in the Secano Interior region of Chile demonstratethe complicated mechanisms by which water moves throughand interacts with vertic soils, and show that the wetting andsealing processes are highly complex. However, an emergentproperty was also clearly observed, as all of the plots showedsimilar runoff thresholds in terms of cumulativeprecipitation. This may in turn simplify future efforts topredict infiltration and runoff across scales.

Stockinger, Michael P.Active Catchment Area as a Controlling Factor ofSpatial Patterns of Transit Time Distributions in aSmall, Forested CatchmentStockinger, Michael P.1; Bogena, Heye1; Lücke, Andreas1;Weiler, Markus2; Vereecken, Harry1

1. Institute for Bio- and Geosciences, IBG-3: Agrosphere,Research Center Jülich GmbH, Jülich, Germany

2. Albert-Ludwigs-University of Freiburg, Freiburg,Germany

Knowledge of catchment response times to precipitationforcing and of transit times of water can be used tocharacterize a catchment’s hydrological behavior. The aim ofthis study was to use one gauging station together withmultiple 18O-isotope monitoring locations along the mainstream and tributaries of a small river to characterize thespatial heterogeneity of a catchment’s hydrological behavior.We present a method suitable for small catchments toestimate the Transit-Time Distribution (TTD) ofprecipitation to any stream point using 18O tracer data,independent of whether the stream point is gauged orungauged. Hourly runoff and precipitation data were used

to determine the effective precipitation for the Wüstebachcatchment (Eifel, Germany), a small, forestedTERENO/TR32 test site. Based on average soil water contentthe modeling period of 2 years was split up in two summerand two winter seasons in order to ensure a good fit of themodel. Given the small size of the Wüstebach catchment (38ha) and its homogenous spruce tree cover, we assumed thederived effective precipitation to be representative for thewhole catchment. For subsequent modeling of stream water18O data we used effective precipitation as an inputvariable and corrected for smaller hydrologically activeresidual area (HARA) during summer months, when parts ofthe catchment become hydrological inactive. Results show adifferent behavior of the catchment’s response time fordifferent catchment wetness conditions, governed by storagecharacteristics. Winter and summer seasons, respectively,show similar response times, with summers reactinggenerally faster due to the shrinking catchment size. TheTTDs across the isotope observation points show locationsmore influenced by shallow source waters than other points,with higher contributions of deep/slow groundwater. Themodel results are verified by independent evaluations of sub-catchment soil properties distributions.

Subin, Zachary M.Representing the Effects of Hillslope-ScaleHydrology on Soil Carbon Distributions within anEarth System ModelSubin, Zachary M.1; Sulman, Benjamin N.1

1. Princeton Environmental Institute, Princeton University,Princeton, NJ, USA

Soil moisture is a crucial control on soil carbon cycling,and its impact on soil carbon accumulation is highlynonlinear due to anoxia and interactions with abovegroundvegetation. Earth System Models (ESMs) generally onlyrepresent the average soil moisture state in grid cells at scalesof 50-100 km, and as a result are not able to adequatelyrepresent the effects of subgrid heterogeneity in soilmoisture, especially in regions with large wetland areas. Weaddressed this deficiency by developing a subgrid hillslope-hydrological model embedded within the Geophysical FluidDynamics Laboratory (GFDL) land-surface model. One ormore representative hillslope geometries are discretized intoland model tiles along an upland-to-lowland gradient ineach grid cell. Each tile has its own surface fluxes andvertically-resolved state variables for soil physics andbiogeochemistry. Inclusion of deep layers down to bedrockallows for physical inclusion of groundwater transport. Thehydrological model is coupled to the Carbon, Organisms,Respiration, and Protection in the Soil Environment(CORPSE) model, which represents soil carbonaccumulation and decomposition including dynamicmicrobial activity, protected carbon pools, and verticalredistribution of carbon through leaching. Soil carbon isvertically resolved in the model, allowing more realisticinteractions with hydrology in wet areas. We presentsensitivities in global and regional soil carbon distribution

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to subgrid hydrological heterogeneity and its representation,including alternative parameterizations of hillslopegeometry (e.g., concave upwards vs. neutral slope profiles),macroporosity, and surface runoff / inundation. Theinclusion of subgrid hydrology can increase the equilibrium0-2 m global soil carbon stock by a factor of ~3, includinglarge realistic increases in peatland-rich areas such as theHudson Bay Lowlands and Western Siberia, in addition topotentially excessive increases in moist and seasonallyinundated areas such as the Amazon. We conclude that themodel allows for more realistic simulation of geographicalvariability in soil carbon while also increasing the sensitivityof biogeochemical cycling to the hydrologicalparameterization. Future work will include simulatingexport of dissolved organic matter to rivers, andinvestigating the interaction of hydrology and soil carboncycling under present conditions at both the regional andglobal scales. This model will allow us to investigate futurechanges in land carbon fluxes caused by the effects ofchanging hydrological regime on soil carbon cycling, as wellas increasing the accuracy of ESM carbon cycle simulationsin wetland-rich regions such as the circumpolar zone.

Tan, AnnTopographic Influence on Spatial and TemporalPatterns of Grassland ProductivityTan, Ann1; Bookhagen, Bodo1; D’Antonio, Carla2; Chadwick,Oliver1

1. Geography, University of California, Santa Barbara, SantaBarbara, CA, USA

2. Ecology, Evolution, and Marine Biology, University ofCalifornia, Santa Barbara, Santa Barbara, CA, USA

Natural landscapes are topographically heterogeneouseven at relatively local scale; this heterogeneity affects plantperformance. For a restoration project to be successful then,the relationship between topography and plant growth mostbe considered to dictate locations of planting. However,while understanding the nature this relationship is critical insuccessful restoration projects, not much is known about it –how exactly do terrain attributes such as aspect andcurvature affect plant establishment and success? We focuson a parameter of success, biomass production, byevaluating the influence terrain attributes has on plantproduction at two different scales: 1m and 12m on threesmall hills in Sedgwick Natural Reserve (SNR), located insouth-central California, through field harvesting andremote sensing on average rainfall years. To describe thetopography, we used a 1m spatial resolution ground-basedlidar digital elevation model (DEM) to calculate several keyterrain attributes: curvature, aspect, and the CompoundTopographic Index (CTI), which indicates areas of potentialwater accumulation in complex landscapes. Biomass wasdetermined in two separate ways: harvest and remotesensing. We harvested 83 1x0.5m2 randomly distributedquadrats of aboveground plant matter at the end of the2011-2012 growing season. Because of the annual nature ofthe vegetation, biomass obtained at the end of the growing

season approximates aboveground net primary productivity(ANPP) for that year. We also used the NormalizedDifference Vegetation Index (NDVI) as a biomass proxy,obtained from monthly 12m resolution AVIRIS (AirborneVisible / Infrared Imaging Spectrometer) flights from Marchto August 2009. The terrain attributes were then regressedagainst field and remote sensing generated biomass values.We found a correlation between aspect and plantproductivity. In March, the south facing slopes had higherNDVI values than the north facing slopes. From April toAugust, the relationship reversed, and the north facingslopes have higher NDVI values. There is no correlationbetween the terrain attributes that described water flow(curvature and CTI) and plant productivity at bothresolutions. Our findings imply limited water redistributionor lack of clear recognizable vegetation response to suchwater transfers during average rainfall years. This isunsurprising as precipitation is often too low to causesaturated flow redistribution at SNR’s clayey soils and theabundant gopher holes makes overland flow rare. Thechanging relationship between NDVI and aspect throughtime lead us to believe we captured the ecosystem transitionfrom a solar insolation limited phase (October – March), to awater limited phase (March – August). Future work focuseson quantifying the seasonal variation in solar insolation andits impact on temperature and evapotranspiration ondifferent aspects. Our study highlights the importance forland managers to consider both topography and theinterannual variability of precipitation when planningrestoration work, as the relationship between productivityand topography is both spatially and temporally dependent.

Troch, Peter A.The Landscape Evolution Observatory (LEO) atBiosphere 2: Opportunities for collaborative Earthsystem research in a controlled environment(Invited)Troch, Peter A.1

1. Hydrology and Water Resources, Univ of Arizona,Tucson, AZ, USA

The University of Arizona Biosphere 2 consists of aunique large-scale experimental apparatus housing sixmodel ecosystems, a team of multidisciplinary scientists, abroad science education and public outreach program, and amodern conference center. On of these six model ecosystemsis the Landscape Evolution Observatory (LEO).LEO consistsof three identical, sloping, 333 m2 convergent landscapesinside a 5,000 m2 environmentally controlled facility. Theseengineered landscapes contain 1-meter depth of basaltictephra, ground to homogenous loamy sand that willundergo physical, chemical, and mineralogical changes overmany years. Each landscape contains a spatially dense sensorand sampler network capable of resolving meter-scale lateralheterogeneity and sub-meter scale vertical heterogeneity inmoisture, energy and carbon states and fluxes. The densityof sensors and frequency at which they can be polled allowsfor measurement to be made that are impossible in natural

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field settings. Embedded solution and gas samplers allow forquantification of biogeochemical processes, and facilitatethe use of chemical tracers to study water movement at verydense spatial scales. Each ~600 metric ton landscape hasload cells embedded into the structure to measure changesin total system mass with 0.05% full-scale repeatability(equivalent to less than 1 cm of precipitation). Thisfacilitates the real time accounting of hydrologicalpartitioning at the hillslope scale. Each hillslope has anengineered rain system capable of raining at rates between 3and 45 mm/hr in a range of spatial patterns. The rainsystems are capable of creating long-term steady stateconditions or to run complex simulations. The precipitationwater supply storage system is flexibly designed in order tofacilitate addition of tracers in constant or time-varyingrates to any of the three hillslopes. This presentation willgive an overview of the research conducted on one of thehillslopes during the commissioning phase (November 2012-September 2013).http://leo.b2science.org/

Trofymow, John A.Developing a 100-year Retrospective CarbonBudget for the Sooke Watershed, Vancouver Island,BCTrofymow, John A.1, 3; Smiley, Byron2; Ussery, Joel4;Niemann, Olaf2

1. Canadian Forest Service, Natural Resources Canada,Victoria, BC, Canada

2. Geography, U. Victoria, Victoria, BC, Canada3. Biology, U. Victoria, Victoria, BC, Canada4. Water Services, Capital Regional District, Victoria, BC,Canada

To address the role that deforestation through reservoircreation as well as forest harvest and natural disturbance,have had on watershed level forest C budgets, historicspatial, inventory and disturbance data were assembled forlands of the Sooke watershed in the Greater Victoria WaterSupply Area (GVWSA). A retrospective carbon (C ) budget forthe watershed for the period 1911 to 2012 is being developedusing the spatially-explicit version of the Carbon BudgetModel of the Canadian Forest Sector (CBM-CFS3). CBM-CFS3 is an inventory-based C budget modelling tool that hasbeen used to simulate forest C dynamics at national,regional, and operational scales and has the capability toinclude lateral transfers of dissolved organic C (DOC) toaquatic systems. In 1911 the 8500 ha Sooke watershed wasdominated by old-growth and mature Douglas-fir forests,when land clearing around the existing 396 ha Sooke Lakebegan, with dam completion and formation of the 480 haSooke reservoir in 1915. Dams were raised and the reservoirwas subsequently expanded in 1970 to 600 ha, 1980 to 650ha, and again in 2002 to 850 ha, resulting in further landclearing for the reservoir and dam infrastructure. Whilesome localized forest harvest occurred in the 1920s and1930s, more widespread forest harvest began in 1954 andover the next 43 years ~2000 ha of forest was cut and

replanted or permanent roads installed. While conversion offorest to reservoirs means a decrease in forest area able tosequester C, reservoir sediments can also potentially serve asa sink for terrestrial C transported in streams, which mightotherwise be respired if it remained in the stream. Such anaquatic DOC flux is an important gap in terrestrial C budgetmodels and currently in CBM-CFS3 the flux assumed to benil. Water quantity and DOC monitoring data from threesubwatersheds in the Sooke will be used to estimate annualC fluxes to the reservoir and data used to parameterize DOCtransfers in the model. Alternative disturbance scenarios andsensitivity analysis of DOC fate will be examined with themodel to determine the relative importance of disturbanceregimes and lateral DOC transfers on watershed level Cbudgets.

Trueman, AdamVegetation as a spatiotemporally heterogeneouscontrol on landscape evolution: A critical zoneapproach to Landscape Evolution ModellingTrueman, Adam1; Wainwright, John1; Densmore, Alex1;Turnbull, Laura1

1. Geography, Durham University, UK, Durham, UnitedKingdom

Feedbacks between Earth’s biotic and abioticcomponents have had and continue to have a profoundinfluence on the evolution of Earth’s atmosphere, biosphere,lithosphere and hydrosphere. Of particular interest to bothgeomorphologists and ecologists is the role such feedbackshave upon Earth’s surface – the region that couples Earth’shydrosphere, biosphere, atmosphere and lithosphere (nowcommonly termed the critical zone). The influence ofvegetation has long been recognised within the critical zone(e.g. Lyell, 1830; Belt, 1874; Gilbert, 1877; Dokuchaev, 1883),whilst recent work has also suggested that terrestrialvegetation can have a profound impact on channelmorphologies (see Gibling & Davies, 2012) and globalbiogeochemical cycles (e.g. Berner, 1997). However only aselection of these complex ecogeomorphic feedbacks havebegun to be understood through harnessing recenttechnological advances such as cosmogenic dating andcomputer modelling. For example, numerous recent studies(e.g. Dietrich et al, 1995; Heimsath et al., 2001; Heimsath etal., 2009; Gabet & Mudd, 2010) have supported one of twodifferent long-standing soil-production functions (SPFs)that relate soil production to soil depth – the humped andthe exponential decay SPFs. These studies have beensupplemented by recent studies which suggest that soilproduction rates are influenced by vegetationstructure/function (e.g. Gabet & Mudd, 2010; Roering et al.,2010) Despite these recent advances in our understanding ofecogeomorphic feedbacks in the critical zone, there has beenrelatively little work on determining the influence vegetationdynamics may have upon SPFs and landscape evolution aswell as the corresponding feedbacks on the vegetationamount and pattern. Progress is hampered by modernLandscape Evolution Models (LEMs) which commonly

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simulate vegetation change relatively simplistically throughtheir ecological components experiencing littlespatial/temporal variability in root and canopy structure,seasonality and/or function. Therefore application of theseLEMs is limited when studying the influence vegetationdynamics may have upon processes within the critical zone.Through utilising a modelling-based approach, this studyaims to improve our understanding of how vegetationdynamics in both space and time can influence soilproduction and landscape evolution. This poster will presentan overview of our current understanding of ecogeomorphicinteractions within the critical zone as a basis for the workcurrently being undertaken concerning the development andcoupling of a spatiotemporally dynamic vegetationcomponent within an existing LEM. Finally, preliminarymodel results associated with hypotheses investigating theinfluence spatiotemporal vegetation dynamics on soilproduction rate and landscape evolution will be presented,emphasizing that different SPFs can emerge as the result ofdifferent process interactions.

Trusiak, AdriannaDisassembly of Phage 6 by Montmorillonite ClayKatz, Al1; Block, Karin A.2; Trusiak, Adrianna2; Gottlieb,Paul3; Alimova, Alexandra3; Wei, Hui3; Morales, Jorge5; Rice,Willaim J.4; Steiner, Jeffrey C.2

1. Physics, City College of New York, New York, NY, USA2. Earth and Atmospheric Science, City College of NewYork, New York, NY, USA

3. Sophie Davis School of Biomedical Education, CityCollege of New York, New York, NY, USA

4. New York Structural Biology Center, New York, NY, USA5. Biology, City College of New York, New York, NY, USA

Bacteriophage are viruses that modulate microorganismpopulations in soils and can transfer genetic material bytransduction. Viruses aggregate with clay minerals,potentially creating viral reservoirs in soils. Therefore, theinteraction between clay minerals and viruses can affectbacterial populations, as well as biogeochemical cycling andthe health of the greater ecosystem. The literature offersconflicting results on the effect of clay on the infectivity ofphage. In this work, the interaction of the enveloped phage6 with montmorillonite clay is examined by TEM andbiochemical analysis. It is observed that virions rapidlyaggregate with the montmorillonite resulting in a loss ofviral infectivity. Analysis of micrographs show that virionsattach to both the negatively charged clay faces andpositively charged edges. The virions exhibit partialdisassembly of the lipid envelope (see Fig. 1) and manyvirions have the envelope totally removed leaving only thenucleocapsid (NC) intact. Band intensities in SDS-PAGE gelsof virus-montmorillonite pellets and supernatantpreparation confirms that the viral particles are almost 100%sequestered into the aggregates. Loss of viral infectivityincreases rapidly when the platelet concentration exceeds thevirion population (See Fig. 2).

Fig. 1. Platelet with two 6 virions attached to edges.

Fig. 2. 6 infectivity as a function of montmorillonite concentration

Turnbull, LauraMechanisms Regulating the Fate of Nitrogen inDrylandsTurnbull, Laura1; Hall, Sharon2; Ball, Becky2; Sparks, Jed3;Grimm, Nancy2

1. Department of Geography, Durham University, Durham,United Kingdom

2. School of Life Sciences, Arizona State Unviersity, Tempe,AZ, USA

3. Department of Ecology and Evolutionary Biology,Corenll University, Ithaca, NY, USA

Like in other areas of the world, drylands are receivingincreasing inputs of nitrogen (N) from the atmosphere dueto combustion and agriculture, with ~ 2 kg N ha-1 yr-1being deposited in the open deserts of the southwestern USand up to ~ 30 kg N ha-1 yr-1in urban regions. The

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processes governing N retention in drylands are likely to befundamentally different compared to mesic ecosystems. Ourconceptual framework posits that novel loss pathways willlimit the retention of N deposition in deserts, and that thestrength of these loss pathways is tied to the distincttemporal and spatial patchiness that characterizes drylandsglobally. We bring together data from multiple studies toexplore the significance of potential N-loss pathways in thedeserts of the southwestern USA and explore how spatialheterogeneity in vegetation and soil properties affects theirrelative magnitudes. Results suggest that biotic processesmay ultimately play a smaller ecological role in the waydeserts function relative to abiotic processes. N lossesthrough gas emissions potentially represent a substantialfraction of N deposition – up to 15-20% of annual Ndeposition, particularly after summer rainfall. Results showthat N losses are significant during high-magnitude rainfall-runoff events, with particulate forms dominating total Nloss. Similarly, wind erosion is significant and accounts forup to ~2-15 kg N ha-1 yr-1 in desert grasslands. Theseaeolian and hydrological transport vectors are most efficientwhere gaps between vegetation are highly connected. Whilethese results provide initial insight into the roles of N-losspathways, research integrating ecology, biogeochemistry,hydrology and geomorphology is required to explore furtherthe potential feedbacks between these processes and theeffects of ecosystem heterogeneity on the fate of Nitrogen indrylands.

Van Haren, Joost L.CO2 sequestration through weathering of basalttefra in the Landscape Evolution Observatory(LEO)Van Haren, Joost L.1; Dontsova, Katerina1; Barron-Gafford,Greg1

1. Biosphere 2, University of Arizona, Oracle, AZ, USA

Weathering of primary silicates is one of themechanisms involved in carbon removal from theatmosphere, affecting the carbon cycle at geologictimescales. Basalt is one of the most reactive rocks and thusa strong contributor to geologic weathering fluxes. TheLandscape Evolution Observatory (LEO), a state of the artfacility at Biosphere 2, Tucson, AZ, consisting of threeidentical 350m2 and 1m deep slopes, allows conductingcontrolled experiments investigating the interactionsbetween atmosphere, hydrosphere, lithosphere, andbiosphere at an unprecedented scale. This study presentsresults of the initial experiments where granular basalt thatserves as a soil medium in LEO was exposed to rainfall. Soilsolution and drainage were collected and analyzed todetermine changes in solution composition. Gas-phase CO2concentrations in the soil were monitored using custom gassamplers and Vaisala CO2 probes and CO2 gas fluxes on thesurface was determined using soil chambers. The goal of thestudy was to determine the impact of precipitation onincipient CO2 driven weathering reactions and inorganic Csequestration in the basalt and how are these reactions

distributed along hillslope flow paths. Results indicate verystrong relationship between water inputs and soil CO2concentrations and fluxes. Within hours of a rainfall eventthe surface CO2 flux increased three fold, while soil CO2concentration was reduced from near atmospheric to<100ppm. In addition significant sequestration and leachingof inorganic carbon was observed, along with significantweathering of basalt and development of heterogeneity insolution-phase composition.

Figure 1. Soil CO2 concentrations as a function of the moisturecontent.

Figure 2. Spatial distribution of DIC concentrations on the LEOhillslope after rainfall.

Vanderlinden, KarlSoil Water Diffusivity Estimation from DistributedWater Content Observations across a RainfedOlive OrchardEspejo-Pérez, Antonio J.1; Giráldez Cervera, Juan V.1;Vanderlinden, Karl2; Pedrera Parilla, Aura2; Martinez García,Gonzalo1

1. Dept. of Agronomy, University of Córdoba, Córdoba,Spain

2. Centro Las Torres-Tomejil, IFAPA, Alcala del Rio, Spain

Soil water sensor networks provide detailed insight intothe spatio-temporal water dynamics across agricultural

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fields and landscapes, while the high resolution observationsoffer possibilities for estimating soil hydraulic properties.Such information is useful to design and develop soilmanagement strategies that optimize simultaneously theconservation of soil and water, e.g. in water erosion-proneolive orchards. In this work a simple method is presented toestimate spatially distributed soil water transmissionparameters using data from a network of water contentsensors installed across a rainfed olive orchard. A total of 99sensors were installed under the canopy, and at adjacentinter-row locations, of eleven olive trees across a 6.8 haexperimental catchment in Southern Spain. Sensors werelocated across the soil profile at depths from 5 to 45 cm, at10-cm intervals. The Mediterranean climate, characterized bya lack of rainfall during an extended period from late springto early autumn, results in a prolonged uninterrupted dryingperiod. Under such conditions the gravitational componentof Richard’s equation becomes negligible as compared to thesuction gradients, and soil water flow can be approximatedby the diffusion equation for horizontal flow in semi-infinite unsaturated porous media. Introducing theBoltzmann transform for the time and depth coordinates ofprofile water content data from drying periods, the diffusionequation becomes an ordinary differential equation fromwhich the diffusivity can be estimated, assuming anexponential relationship between the soil water content andthe Boltzmann coordinate. Soil water diffusivity and itsvariation were successfully estimated within the catchmentwith the proposed method. Diffusivity directly influencessoil water dynamics and its spatial variation elucidateddifferences between areas under olive canopies and inter-rowareas, indicating that the sensor network was able to capturethe effect of individual trees on soil water dynamics acrossthe field.

Relationship between soil water content () and the Boltsmancoordinate () for a location under the tree canopy (UC) and anadjacent inter-row location (IR) . The dashed line represents theexponential fit, with 2 the initial “wet” soil water content, n thenumber of data points and a a fitting parameter

Wacha, KennethTotal Belowground Carbon Allocation in IntenselyManaged LandscapesWacha, Kenneth1; Papanicolaou, Thanos1; Wilson,Christopher G.1

1. Civil Engineering, IIHR - Hydroscience & Engineering,Iowa City, IA, USA

Currently, biogeochemical models lack the ability toaccurately simulate the evolution of total belowgroundcarbon allocation (TBCA) especially in agriculturallandscapes such as in the U.S. Midwest. This limitationinduces high uncertainty in assessing sequestration potentialwhen performing carbon budgets within the critical zone.Many of these models were developed in forest and grasslandsystems under the assumption the systems are homogenousand equilibrated. When comparing agricultural landscapesto forested areas, the soil in the former is not permanentlycovered by plants thereby intensifying the effects ofrainsplash/runoff on soil erosion, soil carbon redistributionand litter incorporation. Adding more complexity, tillagethat occurs in agricultural landscapes not only verticallyredistributes soil carbon through incorporations of rootsand surface litter within the soil column, but also acceleratessoil carbon and litter mobilization laterally atop the soilsurface. Additionally, tillage-induced erosion has long-termimplications on soil carbon storage and overall TBCA bybreaking apart soil aggregates, thereby increasing thelikelihood for enhanced microbial activity, mineralizationand fluxes of carbon dioxide to the atmosphere. Therefore,to accurately simulate TBCA dynamics in agriculturallandscapes it is necessary to account for a series ofhydrological and biogeochemical processes related to TBCAwhich have not been studied in detail before. In this study,some of these limitations were addressed by complementinghillslope event-based and seasonal carbon observationswithin the Clear Creek Observatory with the development ofa coupled modeling framework focused on soil carbonredistribution due to vertical mixing and downslope/lateralmobilization. Few studies have provided updatedgeospatially distributed results of soil carbon while takinginto consideration all of the aforementioned processes andattributes. The framework builds on the coupling of an off-the-shelf spatially distributed erosion hillslope model(Papanicolaou et al., 2010) with the biogeochemical modelDAYCENT. This coupling was deemed important to accountfor the collective effects of rainsplash/runoff and tillage-induced erosion on TBCA across the three dimensionaldomain by predicting routing of clay-size fractions andenrichment ratios. Such results are lacking, especially onevent-based and first-order stream scales watersheds inintensely managed landscapes. Specifically, key physical andbiogeochemical parameters were monitored throughoutseveral growing seasons. Soil samples and respirationmeasurements were taken along various hillslope positions,and sediment was collected at the watershed outlet. Allsamples were analyzed for isotopic signatures of 13C and15N. Rainfall simulation experiments were performed on

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representative hillslope profiles, rainfall intensities, and soiltypes to capture redistribution and runoff rates, evolution ofsoil micro-roughness, and enrichment ratios on an event-based scale. Experimental measurements were used to testthe model on event and seasonal scales to identify howsignals of carbon propagate in space and time.http://www.iihr.uiowa.edu/tpapanicolaou/clear-creek-

watershed/

Wingate, LisaSeasonal contribution of soil CO2 invasion to thetotal CO18O flux from a pine forest ecosystem(Invited)Wingate, Lisa1; Ogee, Jerome1

1. INRA, Villenave D’Ornon, France

The oxygen isotope composition of CO2 in theatmosphere is strongly influenced by the oxygen isotopeexchange of CO2 with leaf and soil water pools across theEarth’s surface. Until recently it was thought that thisisotopic exchange was considerably slower in soils comparedwith leaves. However field estimates have shown that soilisotopic exchange may be up to 1000 times faster thanpreviously estimated for some ecosystems, because of theenzyme carbonic anhydrase. In this talk we will presentseasonal gas exchange observations from a pine forest inSouth West France that demonstrate the importantcontribution of the soil oxygen isotope signal at theecosystem scale. We found that over the entire season theoxygen isotope signal of ecosystem CO2 exchange, derivedfrom nocturnal Keeling plots, was most similar to theoxygen isotope composition of the soil CO2 efflux. Using theisotope-enabled ecosystem model MuSICA, and the isotopicsignals observed in leaf, stem and soil chambers we couldestimate the nocturnal flux rate contribution of eachcomponent to the net ecosystem exchange over the season.In addition we investigated the temporal activity of soilcarbonic anhydrase activity over the growing season and towhat extent it varied with soil surface CO2 concentration,temperature and soil moisture. Conclusions from thisanalysis will be presented and recommendations for futureexperimental studies made.

Wu, ShiliangInteractions between Anthropogenic and SoilEmissions of Nitrogen OxidesWu, Shiliang1

1. Michigan Tech, Houghton, MI, USA

Nitrogen oxides (NOx) play an important role inaffecting atmospheric composition and air quality. Microbialprocesses in soil make significant contributions to NOx inthe atmosphere. Anthropogenic activities, such as increasedfertilizer application, intensified use of fossil fuel (whichwould lead to enhanced NOx emissions and nitrogendeposition), could dramatically affect the nitrogenavailability in the soil and therefore the soil NOx emissions.On the other hand, the increase of soil NOx emissions could

significantly compromise the efforts in domestic NOxemission reductions. Based on both modeling work and fielddata, this study will examine the potential effects ofanthropogenic activities on soil NOx emissions as well as therelative importance of various NOx sources and theirinteractions in the context of global change.

Yakir, DanCarbonyl sulfide (COS), a tracer to separate soilform canopy CO2 exchange (Invited)Yakir, Dan1; Berkelhammer, Max2; Miller, John3

1. Environmental Sciences, Weizmann Inst Sci, Rehovot,Israel

2. Cooperative Institute for Research in EnvironmentalSciences, University of Colorado, Boulder, CO, USA

3. Earth System Research Laboratory, Global MonitoringDivision, NOAA, Boulder, CO, USA

The potential use of COS as tracer of CO2 flux intoleaves, associated gross primary productivity (GPP), andsoils, associated with ecosystem respiration (Re), stimulatedresearch on COS-CO2 interactions during biosphere-atmosphere exchange. This is based on the observation thatCOS co-diffuse with CO2 into vegetation and soils, butwithout an emission outflux. Recent advances in laserspectroscopy and the availability of high precision fielddeployable quantum cascade laser systems resulted withaccumulation in recent years of new results from laboratory-scale control experiments, field studies, atmosphericmeasurements and, consequently, from large scale modelingstudies, all of which demonstrate the potential in the COSapplication to carbon cycle research. These studies alsohighlighted the key uncertainty associated with soil uptakeof COS. Soil uptake is based on dissolution and hydrolysis insoil moisture, which can be enhanced by carbonic anhydrase(CA) that can exist in soil and litter. Our recentmeasurements over the diurnal cycle and across a range ofecosystems indicated that soils act mostly as COS sink,equivalent to 2-6% of canopy uptake during peak activityperiod (temperate summer). The results also indicated thatCOS uptake is influenced by soil moisture and temperature,and net emission can be observed under certain conditions.The importance of CA activities has been demonstrated insoils in CO2 studies using stable isotopes (18O), and forCOS in leaves using anti-sense lines, but quantifying itsimportance for soil COS uptake is still lacking. Dielevolution of the co-variation between COS and CO2 in theambient surface air shows that it reflects the interplayamong the effects of soil, leaf and atmospheric dynamics.Extending observations to background atmosphericmeasurements of the seasonal drawdown in CO2 and COSdemonstrates that comparing drawdowns of CO2 with thatof COS could provide additional constraints on thedifferential responses of photosynthesis and respiration tolocal and regional forcing. Such separation is critical toimprove prediction of future responses of the terrestrialbiosphere to changing environmental conditions.

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Yakirevich, Alexander M.Augmentation of Monitoring Networks UsingInformation Theory and Ensemble Modeling withPedotransfer FunctionsPachepsky, Yakov1; Yakirevich, Alexander M.2; Guber,Andrey3; Gish, Timothy1; Kuznetsov, Mikhail Y.2; Cady,Ralph E.4; Nicholson, Thomas J.4

1. BARC, USDA-ARS, Beltsville, MD, USA2. Department of Environmental Hydrology &Microbiology, Ben-Gurion University of Negev, SedeBoqer, Israel

3. Department of Plant, Soil and Microbial Sciences,Michigan State University, East Lansing, MI, USA

4. ORR, US NRC, Rockville, MD, USA

Improving understanding of chemical transport in soilsincludes comparison and discrimination of differentchemical transport models. The objective of this work was toapply a Kullback-Leibler divergence-based method toaugment a subsurface monitoring network (SMN) fordiscrimination of conceptually different subsurface flow andtransport models. This method is based on computing thetotal information gain using prior probabilities of modelcorrectness. The ensemble modeling with pedotransferfunctions is employed to estimate the variance of thepredicted values. The method was applied to determine thelocation where additional observations are needed todiscriminate models in the tracer experiment conducted atthe USDA-ARS OPE3 research site where a pulse of KClsolution was applied with irrigation water and soil andshallow groundwater were subsequently monitored for fourmonths. A three-dimension model was developed tosimulate the flow and chloride transport, and pedotransferfunctions were used to calibrate and build an ensemble ofmodels. Models were discriminated that included or ignoredthe effect of subsurface soil lenses on the chemical transport.The determination of monitoring locations to augmentexisting ones was conducted on a 2D grid. Explicable andstable solutions were found for the monitoring networkaugmentation. The outcome of this study provides anapproach to future data collection aimed at reducinguncertainties in the conceptual models of flow andtransport in variably saturated soils.

Ye, ShengDerivation of Subsurface StormflowParameterization from Regional Analysis ofStreamflow Recession Curves: A Possible ClimateDependence?Ye, Sheng1; Li, Hong-yi3; Huang, Maoyi3; Ali, Melkamu4;Leung, Lai-yung3; Wang, Shao-wen1; Sivapalan, Murugesu1, 2

1. Geography and Geographic Information Science,University of Illinois at Urbana-Champaign, Urbana, IL,USA

2. Civil and Environmental Engineering, University ofIllinois at Urbana-Champaign, Urbana, IL, USA

3. Hydrology Technical Group, Pacific Northwest NationalLaboratory, Richland, WA, USA

4. Scienze dell’Ingegneria Civile, Universita di Roma Tre,Rome, Italy

Subsurface stormflow is an important component ofthe rainfall-runoff response in mountainous regions, and isstrongly affected by soil hydraulic properties. However, itscontribution is poorly represented in current generation ofland surface hydrological (i.e. rainfall-runoff) models. Weconducted work aimed at deriving universally applicableparameterizations of the storage-discharge relationshiprelating to subsurface flow from a combination of top-down(Darwinian) empirical data analysis and physically based(Newtonian) model simulations. Empirical analysis involvedderivation of storage-discharge relationships fromstreamflow recession curves extracted from 50 easternUnited States catchments. Detailed regression analyses werethen performed between parameters of these empiricalstorage-discharge relationships and the controlling climate,soil and topographic characteristics. Parameterizations ofstorage-discharge relationships were then independentlyderived through simulations with a physically based(Darcian) subsurface flow model for idealized threedimensional rectangular hillslopes, accounting for within-hillslope heterogeneity of soil hydraulic properties, whichwere subsequently up-scaled to the catchment scale byaccounting for within-catchment heterogeneity oftopographic slopes. In both cases, i.e., the theoreticalsimulations as well as empirical analyses of recession curves,the regression analyses with respect to landscape propertiesshowed the significant influence of soil hydraulic propertieson the storage-discharge relationship. One key property isthe vertical profile of the saturated hydraulic conductivity.However, the regression relations in the two cases weresubstantially different, and the divergence between themodel prediction and observed recession coefficientshighlight the importance of accurate estimation of theeffective saturated hydraulic conductivity at catchment scalein subsurface flow generation. This calls for improvedunderstanding of natural heterogeneity of soil hydraulicproperties in real catchments, their relationship to climateand vegetation, and their long-term co-evolution. Indeed,empirical analyses of recession curves indicates a strongclimate (aridity) dependence of the recession curve

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parameters, which needs to be explained and quantified interms of possible co-evolutionary processes.

Yeshaneh, EleniTemporal Variation of Suspended SedimentTransport in the Koga Catchment, North WesternEthiopia and Environmental ImplicationsYeshaneh, Eleni1; Eder, Alexander1, 2; Blöschl, Günter1

1. Civil Engineering, Center for Water Resources Systems,Vienna University of Technology, Vienna, Austria

2. Institute for Land and Water Management Research,Federal Agency for Water Management, Petzenkirchen,Austria

Event sediment transport and yield were studied for 45events in the upstream part of the 260 km2 agriculturalKoga catchment that drains to an irrigation reservoir.Discharge and turbidity data were collected over a period ofmore than a year, accompanied by grab sampling. Turbiditywas very well correlated with the sediment concentrationsfrom the samples (r=0.99) which allowed us to estimate thetemporal patterns of sediment concentrations within events.The hysteresis patterns between discharge and sedimentconcentrations were analyzed to provide insight into thedifferent sediment sources. Anticlockwise patterns are thedominant hysteresis patterns in the area, suggesting smallercontributions of suspended sediment from the riverchannels than from the hill slopes and agricultural areas.Complicated types of hysteresis patterns were mostlyobserved for long events with multiple peaks. For a givendischarge, sediment yields in August and September, whenthe catchment was almost completely covered withvegetation, were much smaller than during the rest of therainy season. The hysteresis patterns and timing suggest thatthe sediment availability from the agricultural areas and hillslopes affects sediment yields more strongly than does peakdischarge. Two distinct types of sediment rating curves wereobserved for the season when the agricultural land wascovered with vegetation and when it was not, indicating thedominating contribution of land use/cover to sedimentyields in the catchment. The rate of suspended sedimenttransport in the area was estimated as 25.6 t year-1 ha-1.

Young, MichaelSoil development, time, and ecosystem function inwater-limited systemsCaldwell, Todd1; Young, Michael1

1. Bureau of Economic Geology, University of Texas atAustin, Austin, TX, USA

The evolution of alluvial deposits to soil is a complexsystem driven by the intrinsic property of time. Soilformation and development result from coupling betweenbiotic and abiotic factors which ultimately influence canopystructure and vigor and they are part of a complex interplaybetween climate and water movement. Soil development isbased on the rate systematic changes in soil properties inrelation to those of the parent material. Unlike all other

fluxes within the soil system, time flows uniformly andirreversibly, and attaining an equilibrium state of a matureor fully-developed soil is thermodynamically improbable. Inpractice, we generally maintain that the larger the number ofhorizons and the greater their thickness, the more mature ordeveloped the soil. Young soils formed on arid alluviumdeposited during the Holocene (deposited within the last 104

year) are weakly developed with minimal horizonation andhigh disorder. By comparison, old soils residing onPleistocene alluvium (sediments deposited between about104 to 107 year) are more strongly developed and have subsoilB-horizons dominated by the pedologic accumulation of silt,clay, calcium carbonate, and other soluble constituents.These two soils are commonly mosaicked across the bajadaresulting in heterogeneity of the soil system we observetoday. These systems are not isolated from theirenvironment and therefore are continuously exchangingenergy and matter with their surroundings. It is such energyand mass flow across various gradients and boundaries (andassociated transformations) that have driven the evolutionand functioning of soils and ecosystems. Time, in a trulylong-term sense, cannot be explicitly removed from ourexperimental design in critical zone studies. Ecology,hydrology, pedology, and geomorphology imply time yet aprofound understanding across disciplines is required tofully understand both the heterogeneity and dynamics of thecritical zone. The synthesis presented will illustrate thecomplex biotic-abiotic feedback that results through timedependent processes of soil pedogenesis in arid regions ofthe desert southwest; at least as we see them today.

Yunjia, LiuArsenic Speciation in the Copper Tailings with theEffects of Magnetite RemovalYunjia, Liu1; Lu, Zhao1; Longbin, Huang1

1. Sustainable Minerals Institute, University of Queensland,Brisbane, QLD, Australia

Arsenic is considered as one of severe metalloidpollutants in the copper tailings, which may pose risks tothe environment and human health. It is known that ironoxides are one of the most important adsorbents of minorelements due to their reactivity and large specific surfacearea, which can coprecipitate and adsorb arsenic. Magnetite(Fe3O4), counting for up to 30% of in copper tailings, mayact as a sink mineral to prevent arsenic mobilization.However, the ore processing has recently changed to removemagnetite as a by-product for economic benefit, whichreduce magnetite concentration from 20 – 30% to 5%. Thusmay affect arsenic speciation and consequently mobilizearsenic in tailings. In this study, we compared the sequentialleaching results from the old copper tailings (total arsenicconcentration 330 mg/kg) with magnetite and new coppertailing without magnetite. There was 34% arsenic adsorbedwith iron in old tailing, comparing to 7% arsenic in newtailings. Organic matter (biochar and mulch) were added inthose tailings and two types of Australian native plants wereplanted in the pot experiment. The leachate was collected

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which may display the different adsorption effects of organicmatter on arsenic due to the reduction of the arsenicadsorption caused by magnetite removal. The results willallow us to understand the changes of arsenic speciationunder the effects of magnetite removal in copper tailingsand show the effects of organic matter addition to thetailings. The results will be interpreted in terms of theinfluence of magnetite and organic matter, which willprovide essential information for further phytoremediationpractice.

Zaharescu, Dragos G.Role of Ecosystem Development in Rare ElementsCycling in an Ultra-oligotrophic System atBiosphere-2Zaharescu, Dragos G.1, 2; Burghelea, Carmen I.1; Dontsova,Katerina1, 2; Presler, Jennifer C.1; Chorover, Jon2; Maier,Raina2; Huxman, Travis3

1. Biosphere-2, University of Arizona, Tucson, AZ, USA2. Soil Water and Environmental Science, University ofArizona, Tucson, AZ, USA

3. School of Biological Sciences, University of CaliforniaIrvine, Irvine, CA, USA

Rare elements (RE) are a group of 17 metals highlydispersed in the Earth’s crust whose economic and scientificimportance has become critical in recent years, withapplications ranging from computing, clean energies, tostudying the origin of sediments and magmas. While there isa relatively significant body of literature on their physicalproperties, the role and fate of RE in the biosphere is stillpoorly understood. For example, few studies from Chinahave suggested that low values of these elements maypromote plant growth. However, there are conflictingevidence and opinions regarding the importance of REs inbiology, particularly because of limitations in theirquantitative analysis. This study originated from a need tofinely test the role of plant-bacteria-mycorrhizae associationsin RE mobilization and uptake particularly at the initialstage of bedrock colonization. For this we setup an ultra-oligotrophic experiment at Biosphere-2 (Tucson, Arizona). Atotal of 4 granular bedrocks were used: basalt, rhyolite,granite and schist. The ecological treatments were acombination of rock extracted bacteria, mycorrhizal fungiand two types of plants: Buffalo grass (Boutelouadactyloides) -a highland species and Ponderosa pine (Pinusponderosa), as well as an un-inoculated control. Anectomycorrhiza (Rhizopogon evadens) and a vesiculararbuscular mycorrhiza (VAM; Glomus intraradices) wereused to inoculate the pines and the grasses, respectively.Infected and non-infected plants were seeded on thepreinoculated mineral media and watered biweekly withnano-pure water. Samples of pore water were collected forthe initial 4 months of ecosystem development (biweekly forfirst 2 months, and monthly thereafter) and analyzed for arange of chemical parameters including RE by ICP-MS.Results of principal component analysis revealed that for allstudied rocks REs clustered together and represented a

major portion in the total variability in pore water elementcontent. Their leaching was higher on rhyolite followed byschist, granite and basalt, most likely being related withdifferences in their mineral contents. The cluster alsodisplayed significant differences between control andecological treatments with incremental values for theecosystem growing on basalt, rhyolite and granite and adecrease on schist. Pine treatment had a significant effect onrhyolite as compared to grass in terms of increased elementrelease. Moreover, VAM significantly increased leaching onbasalt and rhyolite. Regarding element uptake by plants,data analysis revealed that roots had generally highercontent than shoots/leaves. VAM treatment clearly enhancedthe accumulation of certain elements including Y, La, Ce, Pr,Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu on basalt andrhyolite, as compared to un-inoculated plants. The findingsprovide clear quantitative evidence of an important effect ofecosystem settlement on the initiation on RE cycling,specifically on the effect of arbuscular mycorrhizae.

Zapata-Rios, XavierPEDON SCALE SOIL MOISTURE AND WATERFLUXES DYNAMICS DURING EXTREMELY DRYYEARS IN A HIGH ELEVATION SNOWDOMINATED LANDSCAPEZapata-Rios, Xavier1; Troch, Peter A.1; McIntosh, Jennifer1

1. Hydrology and Water Resources, University of Arizona,Tucson, AZ, USA

High elevation semi-arid ecosystems are water limitedenvironments where the timing and amount of wateravailability is a fundamental factor that controls processessuch as weathering, organic matter decomposition, soilrespiration, nutrient uptake, and biomass productionamong others. In turn, water fluxes at higher elevations arecontrolled by interactions between climate, vegetation andsoils. Understanding of these interactions has been hinderedby a lack of integrated measurements of governing fluxesand states. In the southwestern US, high elevationcatchments are snowmelt dominated and recent research hasshown a reduction in snowpack accumulation. The possiblealterations in hydrologic pathways such as evaporation,runoff, infiltration, water residence time due to thesereductions remain poorly understood. The main goal of thisresearch is to improve our understanding of soil moisturedynamics and soil water fluxes at the pedon scale duringextremely dry conditions in the southwestern United States.There are high confidence predictions that snowpacks willcontinue to decline in northern New Mexico through theyear 2100 and projections of snowpack accumulation formid-century (2041-2070) show a marked reduction for snowwater equivalent (SWE) of about 40%. During 2011, 2012and 2013 total winter precipitation in the Jemez Mountainswas reduced by 42%, 9% and 46%, respectively, compared toaverage conditions (353mm). Reductions of SWE duringthese years compared to average conditions (256mm) were56%, 26% and 54%, respectively. The years 2011 and 2013were the driest winters in terms of snow accumulation

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measured during the last 30 years on record. Similarly, thesummer seasons 2011 and 2012 were dry and the totalrainfall during the summer monsoons were 15% and 27%below average conditions (357mm). This study integrates co-located direct observations of snow depth, rainfall, radiation,air temperature, eddie covariance measurements, and soilmoisture at four soil pits into a one dimensional pedon scalemoisture dynamics and soil water balance model.Evaporation, throughfall, vegetation water use, water storageand infiltration are modeled at soil pits located underdifferent tree canopy coverage and terrain aspect at a similarelevation of about 3000 meters on a landscape dominated bydensely welded Bandelier Tuff (Tshrige Member) andassociated rhyolite/rhyodacite rocks. Model results arevalidated by comparing soil moisture measurements and soilsolution water stable isotopes at three different depths ineach soil pit. The study site and climatic conditions duringthe time period of analysis provide a unique setting andopportunity to study water partitioning, vegetation wateruse, deep infiltration and water residence time at the soilpedon scale under extremely dry conditions.

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