Fear and Leaching in Michigan

or,

Dude, where’s my nutrients?

Fear and Leaching in Michigan

or,

Dude, where’s my nutrients?

Emily Farrer, Joshua Haag, Joel Perkovich , Katherine Windfeldt

IntroductionIntroduction

Properties of SoilPhysicalChemicalBiological

Synthesis of Lab and Field Data The Development of a Northern Oak Ecosystem

Physical Properties of SoilPhysical Properties of Soil Texture

– Sand

H20 Holding Capacity– 0.12 cm3 H2O/cm3 Soil– Lowest of all sites

Bulk Density– 1.1 g/cm3 – 2nd Lowest behind NH

Chemical AnalysesChemical Analyses

CEC - Lowest CEC of all sites at 2.2 cmolc/kg (other sites range 3.86-8.71 cmolc/kg)- Thus, smallest nutrient holding capacity of all soils

Base Saturation - Lowest BS of all sites at just 13% (other sites range from 97-99%)

pH- Most acidic of all sites at 4.21 (Mixed Oak highest pH at 5.97)

Soil Biological PropertiesSoil Biological PropertiesProperty Value Relative amount

Soil organic matter 3.06% lowest

Microbial biomass 5.3 g/m2 lowest (w/ OH)

Microbial respiration 12.9 ug/g/d lowest

Specific respiration 304 mg/g/d intermediate(OH higher)

Net mineralization 0.098 g/m2/d lowest

Nitrification 0.002 g/m2/d lowest

C resp./N min. 14.3 ugC/ugN intermediate (MO lower)

Ecosystem Biological PropertiesEcosystem Biological Properties

Ecosystem Biomass

  Mg/ha % total

Aboveground

179.0 79.7

Forest Floor 11.5 5.1

Soil 34.0 15.1

Nitrogen Pools

  kg/ha % total

Aboveground

392.7 24.8

Forest Floor 86.2 5.4

Soil1105.

069.8

Low ecosystem biomass and N compared to other forests

Aboveground and forest floor second lowest (OH lowest)Soil biomass and N pools lowest

Structure / Texture- Well-sorted, sandy PM from former lake bed = larger particle size, weak structure and

sandy texture

Bulk Density (Db)- Well-sorted (homogenous), loosely packed soil results in second lowest Db

` at 1.1 gm/cm3 (other sites range 1.02-1.34)

CEC / Base Saturation - Lowest CEC at 2.2 cmolc/kg 90% sand and 3% clay = weak electronegative charge for CEC- Lowest BS at 13%

Role of topography / fire and well-drained sandy PM = nutrient loss

Available Water Content- Lowest AWC at 0.12 cm3 H20/cm3 soil (other sites range 0.14-0.44)- well-drained sandy PM, lower elevation and southern aspect = H20 loss

pH - Most acidic at 4.21, Non-calcareous PM offers no buffer for soil acidification via weathering

Northern Oak PhysiographyNorthern Oak Physiography

Soil: Field and LabSoil: Field and Lab

Sandy and acidic throughoutLab data supported

Little structureLow OM

Moderately shallow, weak profileWell-drained – weatheringLow OM, no humus accum.

O horizon thinA shallow

Low biomass in forest floor and soil

E weak Bs weak C sand

Profile

SOM rules!SOM rules!

SOMWater holding capacity

Structure

Color

CEC (& anion EC)

Base SaturationpH

Microbial biomassMicrobial respiration N mineralization NPP

VegetationVegetationHistory

1880’s white pine logged, big burnNatural fire regime until 1930 when human fire suppression began

CompositionOverstory– black oak, white oak, red oak, red maple

Understory / Ground Cover– white pine, red maple, sassafras, blueberry, wintergreen,

Pensylvania sedge

VegetationVegetationLow Biomass - 224 Mg/ha

Lowest AWC 0.12 cm3 H2O/cm3 soilLowest Nutrient Availability

– Nitrogen content of 1584 kg/ha– CEC of 2.2 cmol/kg– BS of 0.13

Species Composition – Dry/AcidicLowest AWC 0.12 cm3 H2O/cm3 soilLowest Nutrient Availability Lowest pH of 4.21Fire regime

Perpetuation of systemFire regime/Dry siteOak species

The Development of a Northern Oak Ecosystem

The Development of a Northern Oak Ecosystem

•Young soil•Limited weathering•Low CEC (and non-calcareous parent material) •Well drained (low FC and AWC) -> Loss of nutrients by leaching

Nutrients CEC

Soil Development and Ecosystem Feedbacks

Soil Development and Ecosystem Feedbacks

SOM

Nutrients CEC

•Few nutrients -> low biomass•Low biomass -> little SOM•Little SOM -> Low CEC•Loss of nutrients by leaching

Soil Development and Ecosystem Feedbacks

Soil Development and Ecosystem Feedbacks

Nutrients CEC

Nutrients

•Physiographic and topographic characteristics -> prone to fire

•Loss of nutrients by burning and leaching

Summary:Summary: Young, relatively unweathered soil Susceptible to leaching

Loss of nutrientsLow productivity and biomassLow SOM and CEC

Susceptible to fireLoss of nutrientsLow productivity and biomassLow SOM and CEC

Positive feedbacks maintain low biomass