Assessing Wetland Functional Condition Natural Resources … · drology, Biogeochemistry, Native Plant Community, and Fish/Wild- ... Methods 5 Site selection ... Assessing Wetland

Assessing WetlandFunctional ConditionChange inAgricultural LandscapesS. Diane EcklesNatural Resources Conservation ServiceWashington, DC

Alan Ammann, Ph.D.Natural Resources Conservation ServiceDurham, New Hampshire

Stephen J. BradyNatural Resources Conservation ServiceFt. Collins, Colorado

Sam H. DavisNatural Resources Conservation ServiceJackson, Mississippi

J. Christopher HamiltonNatural Resources Conservation ServiceColumbia, Missouri

Julie HawkinsNatural Resources Conservation ServiceDover, Delaware

Delaney JohnsonNatural Resources Conservation ServiceJackson, Mississippi

Norman Melvin, Ph.D.Natural Resources Conservation ServiceLaurel, Maryland

Rodney O'ClairNatural Resources Conservation ServiceJamestown, North Dakota

Robert SchiffnerNatural Resources Conservation ServiceDodge City, Kansas

Ramona Warren1

Natural Resources Conservation ServiceVicksburg, Mississippi1 Current location: Corps of EngineersVicksburg District, Vicksburg, MS

NaturalResourcesConservationService

WetlandTechnicalNote No. 1

March 2002

March 2002

The U.S. Department of Agriculture (USDA) prohibits discrimination in allits programs and activities on the basis of race, color, national origin, sex,religion, age, disability, political beliefs, sexual orientation, or marital orfamily status. (Not all prohibited bases apply to all programs.) Persons withdisabilities who require alternative means for communication of programinformation (Braille, large print, audiotape, etc.) should contact USDA’sTARGET Center at (202) 720-2600 (voice and TDD).

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A copy of this publication can be accessed via the Internet at:

www.nhq.nrcs.usda.gov/land/index/publication.html

i(190-Functional Assessment—Wetland Technical Note No. 1, March 2002)

Acknowledgments

The authors wish to thank their colleagues Dr. Liz Cook (NRCS, Mis-souri), Doug Helmers (NRCS, Missouri), Marcus Miller (NRCS, Mon-tana), Charles Rewa (NRCS, Wildlife Habitat Management Institute),Bob Sennett (NRCS, Utah), Delmar Stamps (NRCS, Mississippi StateOffice), and Dr. Bill Wilen (Director, National Wetlands InventoryProgram, U.S. Fish and Wildlife Service, Arlington, Virginia) for theirearly participation on the Wetlands Functional Assessment PilotWorkgroup and contributing their thoughts and ideas to the pilot effort.Special thanks to Norm Prochnow (retired, NRCS, North Dakota) forhis critical review of the early draft. The document was significantlyimproved by comments from Dr. Mark Brinson (East Carolina Univer-sity), Dr. Chip Euliss (USGS, Northern Prairie Wildlife Research Cen-ter), Robert Gleason (USGS, Northern Prairie Wildlife Research Cen-ter), Howard Hankin (NRCS, Ecological Sciences Division), Dr. WadeHurt (NRCS, National Soil Survey Center), Dr. Terry Sobecki (NRCS,Resource Assessment Division), and Michael Whited (NRCS, WetlandScience Institute). Dennis Thompson (NRCS, Ecological Sciences Divi-sion) provided material and input on the recommendation regardingdeveloping Ecological Site Descriptions for wetlands. Thanks areoffered to USGS, Northern Prairie Wildlife Research Center, particu-larly Bob Gleason and Tom Sklebar for providing digital coverages andassociated source information for the Prairie Pothole Region in figure 1.The document also benefited from the critical review and editing byAnne Henderson, NRCS, Resource Inventory Division, whose attentionto detail is evident throughout the document. Appreciation and recogni-tion is extended to the National Cartography and Geospatial Centerstaff, Fort Worth, Texas, particularly Lovell Glasscock for contributinghis editorial and design expertise. The senior author extends apprecia-tion to the co-authors and the entire Wetlands Functional AssessmentPilot Workgroup for the time and effort each contributed to the pilot.

The authors also wish to acknowledge the assistance, participation, andinformation provided by the following individuals in the sampling ofrestoration and reference sites, development of GIS coverages, or otheractivities that supported the pilot:

Mark Anderson, NRCS, North DakotaDoug Berka, Soil Scientist, NRCS, Platte City, MissouriPhil Brown, Biologist, U.S. Corps of Engineers, St. Louis, MissouriJohnny Cross, Area Biologist, NRCS, Lafayette, LouisianaDoug Dupin, GIS Specialist – RAD, NRCS, Washington, D.C.Robert Glennon, State Biologist, NRCS, Little Rock, ArkansasAlan Holditch, State Forester, NRCS, Jackson, MississippiDoug Helmers, Biologist, NRCS, Moberly, MissouriW. Matt McCauley, Resource Soil Scientist, NRCS, Benton, IllinoisDave Moffitt, GIS Facility Coordinator–RAD, NRCS, Washington, D.C.Michael Nichols, State Biologist, NRCS, Alexandria, LouisianaNorm Prochnow, Soil Scientist (retired), NRCS, North DakotaTravis A. Rome, Cartographer, NRCS, Kansas State Office

ii (190-Functional Assessment—Wetland Technical Note No. 1, March 2002)

Executive Summary

For more than a century, wetlands on private lands have been modi-fied for growing crops, raising livestock, harvesting timber, buildingof infrastructure to support development expansion, and, in recenttimes, aquaculture. The individual and societal benefits provided bywetlands are well documented, and because of these benefits Fed-eral, State and local government agencies and public and privateorganizations have worked together over the past several decades toreverse the decline of wetland acreage. More recently, the need toprotect and restore wetland functions has been recognized. Studiesinvestigating the relationship between historical and current activi-ties in the surrounding landscape and wetland condition have con-cluded that the level of wetland functioning is determined in part bythis relationship. If wetlands are to provide benefits at an optimumlevel, efforts to manage activities affecting wetlands must alsoinclude those beyond the wetland boundary.

The U.S. Department of Agriculture (USDA), Natural ResourcesConservation Service (NRCS) identified healthy and productive

wetlands sustaining watersheds and wildlife as one of its nationalStrategic Plan objectives (USDA, NRCS 1997). To address thisobjective, NRCS initiated a National Wetlands Functional Assess-ment Pilot to determine whether NRCS was achieving a net increasein wetland function on agricultural lands. The pilot also providedthe means to determine how the agency could achieve a more com-prehensive approach to assess and track wetland functional condi-tion over time. A workgroup was assembled from within NRCS toconduct a study in geographic locations historically and currentlyimportant to agricultural activities. Restoration of wetlands throughUSDA programs and NRCS technical assistance in these regions isintended to increase the wetland base that has experienced some ofthe greatest losses in the conterminous United States because ofagricultural activities.

Three geographic regions were selected for sampling: the NorthernPrairie Pothole Region (NPPR); the Central and Lower MississippiAlluvial Valley (CMV and LMAV); and the High Plains (HP). Wet-lands that are dominant in each of these regions and also make upthe majority of wetlands restored were selected. Approximately 15sites that have been targeted for restoration through USDA pro-grams or have benefited from NRCS technical assistance were se-lected, as were approximately 15 reference wetlands that serve,together with the restoration sites, to provide a snapshot of wetlandfunctional condition in each of the three regions.

To sample wetland functions directly and scientifically would becost prohibitive and time consuming. Instead, the pilot workgroupelected to use a method of assessing wetland functions that requireswetlands first be classified based on water source, hydrodynamics,and geomorphic location, and then sampled using models developedfrom a reference wetland dataset specifically for that class. Themethod is commonly referred to as the hydrogeomorphic method or

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Assessing Wetland Functional Condition Change in Agricultural Landscapes

(190-Functional Assessment—Wetland Technical Note No. 1, March 2002)

HGM (Brinson 1993; Smith et al. 1995), and is used by NRCS toimplement “Swampbuster” provisions of the 1985 Farm Bill, asamended. It is also identified in National Conservation PracticeStandard Nos. 656, 657, and 658 as a method to conduct pre- andpost-functional assessments on lands targeted for wetland restora-tion, creation, or enhancement by NRCS. Wetlands having the samehydrogeomorphic characteristics exhibit similar functions, andtherefore can be placed in the same hydrogeomorphic class.Hydrogeomorphic classes can further be characterized by regionalsubclasses, which are described by large-scale factors such as ho-mogenous climate and geology. The subclasses identified for thisstudy are temporary and seasonal prairie pothole wetlands that aredominated by ground water recharge processes in the NPPR; for-ested, low-gradient riverine wetlands, often referred to as bottom-land hardwood wetlands, of the CMV and LMAV; and playa wetlands,a prominent wetland type occupying depressions of varying sizes onthe HP.

The HGM functional models are used to assess wetland functional

capacity for an individual wetland at any point in time. Wetlandfunctional capacity is used to assess the relative condition of awetland to perform a suite of functions characteristic of an HGMsubclass. Functions typically fall into four general categories: Hy-drology, Biogeochemistry, Native Plant Community, and Fish/Wild-life Habitat. Wetlands with a high functional capacity for all func-tions exhibit sustainable functional capacity. A functional capac-

ity index (FCI) is developed for each function, and ranges from zero(unrestorable) to one (highest sustainable functional capacity).

Restoration and reference sites were sampled once during 1998. FCIvalues calculated during 1998 for the restoration and reference sitesrepresent current conditions ( T1). Functional capacities for condi-tions before restoration (T0) at the restoration sites were estimatedbased on the FCI values calculated for agriculturally altered sitessampled from the reference wetland population, except for theLMAV where they were independently estimated. A net change infunctional capacity was determined for each site (T1 – T0). MeanFCI values were calculated for T0, T1, and the net change for eachfunction. Median FCI values were calculated for current conditionsfor each function to compare restoration and reference sites. Sum-ming of FCI values across functions is not appropriate, nor is sum-ming of functions across subclasses. HGM models are designedspecifically for a particular wetland subclass. Because of the smallsample size, the results presented are not statistically significant.

The results of this pilot indicate that there is a modest relativeincrease in mean functional capacity for wetland restoration sites onagricultural lands within the three geographic regions sampled.More importantly, the results indicate that the relative condition ofmany of the restoration sites is not at the highest sustainable func-tional capacity. Several possible reasons for this include vegetation

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structure, historic, and current land use activities in the surroundinglandscape, lack of appropriate restoration techniques, landownerpreferences for establishing a wetland subclass other than the onefitting the landscape, and modification of the restoration site to ad-dress adjacent landowner concerns with hydrologic restoration.However, the results do provide insight into the challenges faced byNRCS to restore wetlands at sustainable conditions. The followingrecommendations are discussed as a multifaceted approach to moni-tor wetland functional conditions:

1) Implement broad-scale wetland assessments2) Implement site-specific wetland assessments3) Add additional wetland elements to the National Resources Inventory4) Identify wetland functional subclasses before restoration5) Implement a geospatial wetland restoration strategy6) Develop Ecological Site Descriptions for wetlands

v(190-Functional Assessment—Wetland Technical Note No. 1, March 2002)

Contents:

Assessing Wetland FunctionalCondition Change in AgriculturalLandscapes

Introduction 1

Study Area 3

Methods 5Site selection ............................................................................................ 5Wetland functional assessment procedure ....................................... 5Statistical analysis .................................................................................. 7

Results 7Temporary and seasonal Prairie Pothole wetlands, NPPR ............ 7Forested, low-gradient riverine wetlands, LMAV ............................ 9Forested, low-gradient riverine wetlands, CMV ............................. 11Playa wetlands, the High Plains ......................................................... 13

Discussion 14Restoration site vegetation structure ............................................... 16Landscape alteration ............................................................................ 18Temporary and seasonal Prairie Pothole wetlands, NPPR .......... 19Forested, low-gradient riverine wetlands, CMV and LMAV ......... 22Playa wetlands, the High Plains ......................................................... 23Hydrogeomophic method model refinement and validation ....... 23

Recommendations 25

Summary 28

Literature Cited 29

AppendixesAppendix A: Description of Study Area ....................................... A–1Appendix B: HGM Functional Models and Variables ................ B–1Appendix C: Restoration Site FCI Values at T0 and T1 ............ C–1

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Tables Table 1. Wetland classes categorized by the hydrogeomorphic 2classification

Table 2. Functions assessed for three wetland hydrogeomorphic 6subclasses

Table 3. Change in mean FCI (T1 – T0) for each function within 8a subclass

Table 4. Comparison between reference and restoration site 10median FCI values for functions sampled in threewetland hydrogeomorphic subclasses

Table 5. Comparison of differences in median FCI values 12betweenthe CMV (MO) and LMAV (AR, LA, MS) andrestoration reference sites

Table 6. Comparison of median FCI values among vegetation 12stages for reference and restoration sites, CMV (MO)

Table 7. Comparison of median FCI values between CMV (MO) 13and LMAV (AR, LA, MS) mature forested, low-gradientriverine reference sites

Table 8. Comparison of median FCI values among restoration 14sites, reference sites and agriculturally altered playawetlands, the High Plains (KS)

Table 9. Percentage of restoration sites grouped by FCI value 15categories at T1

Table 10. Comparison of mean FCI values over time for nutrient 17cycling function, herbaceous (NPPR) and forested(LMAV – MO/IL) restoration sites

Table 11. Site index range for tree species common to soils of 17the Forested, Low-Gradient Riverine Subclass, CMVand LMAV

Table 12. Extent of palustrine wetlands by broad land cover type 19

Table 13. Temporal and spatial comparison of mean FCI values 22 of habitat functions between temporary and seasonalprairie pothole restoration sites, NPPR

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Figures Figure 1. Geographic regions selected for assessing wetland 4

functional condition

Figure 2. Net change in wetland extent between 1982 and 1992 18

within NRCS administrative regions

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Acronyms and AR Arkansas

Abbreviations: BLH Bottomland Hardwood Wetlands

CFR Code of Federal Regulations

ChE Cholinesterase

CMV Central Mississippi Valley

CRP Conservation Reserve Program

EMAP Environmental Monitoring and Assessment Program

FCI Functional Capacity Index

FSA Farm Service Agency

GIS Geographic Information System

HGM Hydrogeomorphic method

HP High Plains

HUC Hydrologic Unit Code

KS Kansas

LA Louisiana

LMAV Lower Mississippi Alluvial Valley

MAV Mississippi Alluvial Valley

MLRA Major Land Resource Area

MO Missouri

MS Mississippi

ND North Dakota

NPPR Northern Prairie Pothole Region

NPR Northern Prairie Region

NRCS Natural Resources Conservation Service

NRI National Resources Inventory

PPR Prairie Pothole Region

RAD Resource Assessment Division

SCS Soil Conservation Service

SHP Southern High Plains

T0 Time Zero, Prior to restoration

T1 Time One, After restoration initiated

T2 Time Two, Year 2000

T5 Time Five, Year 2003

USDA United States Department of Agriculture

USGS United States Geological Survey

USLE Universal Soil Loss Equation

WPA Waterfowl Production Areas

WRP Wetland Reserve Program

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Assessing Wetland Functional Condition

Change in Agricultural Landscapes

Introduction

In 1893, a 47-mile-long levee was constructed alongthe Mississippi River from the Arkansas state line toNew Madrid, Missouri. By 1910 the Federal Govern-ment had assumed maintenance of the levee to ensurethat it would prevent flooding of the Mississippi Riverbottomland hardwood wetlands that had been con-verted to productive agricultural land. Federal fundswere now used to support river commissions to buildextensive levees systems up and down the MississippiRiver. The reclamation of the fertile bottomlands ofthe river had begun under the Federal mandate toexpand agriculture and commerce.

Between 1899 and 1919, more than 250 drainagedistricts were formed to undertake the draining of thewetlands in the lower Mississippi River basin. Morethan 2,900 miles of drainage ditches were constructedto affect more than 1.7 million acres of worthless

swamp land along the Mississippi River in the south-eastern counties of Missouri (Hidinger 1919; MissouriBureau of Labor Statistics 1910). Only one-tenth ofthe virgin bottomland hardwood forest remained by1919 in the lower Mississippi River drainageway. Themajor part of it was in cultivation and the remainingcutover bottoms actively going into cultivation at thetime (Hidinger 1919).

The 1893 Missouri law opened the door to reclama-tion of idle bottomland. This was one of many stateand federal initiatives within the past 200 years spe-cifically developed to target the conversion of U.S.wetlands. Between 1937 and 1977, an estimated 2.7million acres of bottomland hardwood wetland waslost through construction of drainage ditches and leveesin the Mississippi Alluvial Valley (Taylor et al. 1990).

In the Prairie Pothole Region, drainage of the mostproductive waterfowl breeding habitat in this countryhad caused conservationists in the 1930’s to demandthat the drained potholes and other wetlands through-out the United States be restored (Page et al. 1938).Losses of prairie pothole wetlands were estimated inthe 1970’s at more than 4 million acres. Most of these

losses are attributed to agricultural drainage andconversion to cropland (Tiner 1984). The historicalextent of playa wetlands throughout the High Plains isunknown. However, current estimates indicate thereare between 25,000 – 30,000 playa wetlands on theSouthern High Plains, an area of intensive agriculturaluse since the 1920’s (Luo et al. 1997; Bolen et al. 1989;Osterkamp and Wood 1987; Guthery and Bryant 1982).

In 1997, the U.S. Department of Agriculture (USDA),Natural Resources Conservation Service (NRCS)identified healthy and productive wetlands sustain-

ing watersheds and wildlife as one of its NationalStrategic Plan objectives (USDA, NRCS 1997). Toachieve that objective, NRCS identified a net increase

in wetland functions on agricultural land by theyear 2000 as a Strategic Plan Performance Measure.This effort was initiated in March 1998 with establish-ment of an interim National Wetlands FunctionalAssessment Pilot Workgroup.

The Workgroup identified several key geographicareas where wetland restoration on agricultural landshas significantly involved NRCS funds and technicalassistance. Working from a draft strategy prepared bythe NRCS Resource Assessment Division, theWorkgroup decided to use available NRCS interim ordraft functional assessment models. The models hadbeen developed as part of the application of thewetland functional assessment tool, An Approach for

Assessing Wetland Functions Using Hydrogeomorphic

Classes (HGM), Reference Wetlands and Functional

Indices (Smith et al. 1995) to implement wetlandconservation provisions of the 1985 Farm Bill andsubsequent amendments. The HGM wetland functionalassessment approach was developed by representa-tives from several Federal agencies, including NRCS.

The HGM approach to wetland functional assessmentis based on the premise that wetlands can be catego-rized into one of seven classes based onhydrogeomorphic characteristics (landscape position,hydrologic sources, and hydrodynamics). The classesand examples of each are shown in table 1. Wetlandsthat have similar hydrogeomorphic characteristicsexhibit similar functions, and therefore can begrouped into the same hydrogeomorphic class(Brinson 1993).


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Hydrogeomorphic classes can be further classifiedinto HGM regional subclasses. Regional subclassesare described by homogenous climate, geology, andother large-scale factors involved in developing wet-land functions at some defined geographic scale(Smith et al. 1995). A descriptions of HGM subclassesare provided in Appendix A: Description of StudyArea.

The HGM approach involves the development offunctional assessment models, which are used toassess wetland functional capacity for an individualwetland at any point in time. Because of the difficultyand cost of measuring wetland functions in absoluteterms, these models provide a more efficient means ofassessing the relative capacity of a wetland to per-form a suite of functions characteristic of an HGMsubclass. The functional capacity of a wetland is oneway of quantifying wetland health or condition. Thecondition of a wetland is determined by the degree towhich the wetland’s hydrological, biogeochemical,and biotic characteristics have been altered by an-thropogenic activities within the wetland as well aswithin the landscape. Wetlands with a high functionalcapacity for all functions exhibit sustainable func-tional capacity. As defined by Smith et al. (1995),wetlands and landscapes that have not been impactedby long-term anthropogenic alterations are consid-ered sustainable if structural components and physi-

cal, chemical, and biological processes in the wet-

land and surrounding landscape reach the dynamic

equilibrium necessary to achieve the highest sustain-

able functional capacity.

Therefore, those wetlands and landscapes that haveundergone the least amount of anthropogenic alter-ation are those that exhibit sustainable functionalcapacity. For purposes of this document, the termssustainable, sustainable functional capacity, sus-

tainable functional condition, and highest sustain-

able functional capacity refer to the definition pro-posed by Smith et al. (1995) and are interchangeablein meaning.

In many cases, the landscapes in which restorationsare occurring have changed considerably duringhistoric times. In the Prairie Pothole Region, regionalground water levels are lower than historic levelsbecause of agricultural drainage (Euliss and Mushet1999; Galatowitsch and van der Valk 1994). Agricul-tural activities within temporary wetlands have re-sulted in lower diversity of plant species and greaterpercentages of unvegetated bottom in the wetmeadow communities (Kantrud and Newton 1996).Fragmentation and drainage of prairie potholes haveresulted in replacement of wetland complexes withisolated wetlands. Often the isolated wetlands remain-ing in the landscape are the larger semipermanentwetlands that were historically too costly to drain(Galatowitsch and van der Valk 1994). Restoration ofprairie potholes that relies on seed banks orpropagule dispersal from nearby wetlands to reveg-etate sites will likely result in compositional differ-ences and fewer species in restored wetlands becauseof impacts from intensive, long-term cropping(Galatowitsch and van der Valk 1996; Weinhold andvan der Valk 1989).

Table 1. Wetland classes categorized by the hydrogeomorphic classification (Brinson 1993)

Class Example

Depressional Wetlands that occupy a concave feature in the landscape such as prairie potholes

Lacustrine Fringe Freshwater marshes along a lake or pond shoreline

Tidal Fringe Regularly flooded salt marshes, mangrove swamps

Slope Wetlands along floodplain side slopes where ground water flow is discharged alongthe slope surface because of bedrock, a confining layer or other surficial feature

Riverine Wetlands along a surface water system, such as a river or creek, where the hydrologicflow is unidirectional, such as bottomland hardwood wetlands

Mineral Flats Wetlands on a stream interfluve with a predominantly mineral soil

Organic Flats Wetlands dominated by the vertical accretion of organic matter on interfluves

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Extensive levee construction along the Mississippi Riverfor 100 years has resulted in:

• altering hydroperiods,• clearing of bottomland hardwood wetlands for

agriculture and timber production,• contaminating wetland water columns and sedi-

ments with agricultural runoff, and• extensive fragmenting of the forested matrix

historically characterizing such systems (Harrisand Gosselink 1990; Taylor et al. 1990; Odum andLarson 1980; Cairns et al. 1980).

The landscape of the Southern High Plains in which themajority of playa wetlands are embedded (Bolen et al.1989) is characterized by intensive irrigated agricul-ture and grazing (Haukos and Smith 1993; Nelson etal. 1983). Such land uses have resulted in modifyingplaya basins by:

• lowering of surface water caused by digging of pits tohold irrigation water;

• increasing the length and depth, as well as thetiming, of water on the playas from the addition ofirrigation tailwater;

• contaminating playa soils and surface water fromfeedlot runoff; and

• removing native vegetation through direct crop-ping and grazing of the playa (Bolen et al. 1989).

Such changes in the landscape are a challenge torestoration, as it involves attempting to return a sustain-able landscape feature within a matrix from which it didnot develop. Whether sustainable wetland ecosystemshave been restored is the subject of this document.

The results presented here address the outcome ofapplying the available interim and draft HGM modelsfor three hydrogeomorphic regional subclasses. Thisassists NRCS in measuring their contribution towardrestoring wetland functions on agricultural lands. Thenumeric values calculated for the functions of the wet-lands assessed represent as much of the range of vari-ability in restoring wetland functions as could be sup-ported with the funds provided. However, it is impera-tive for readers and NRCS decisionmakers to understandthat the numeric values represent a small sample size ofthe wetland types assessed. Therefore values shouldnot be used to establish a functional capacity numeri-cal baseline. Rather, the results of the pilot should beused to help formulate a cost-effective and ecologicallymeaningful mechanism to assess and track wetlandfunctional capacity in different landscapes over time.

Study Area

Hydrogeomorphic regional subclasses were initiallyidentified within five geographic areas by theWorkgroup: the Central and Lower Mississippi Valley,the High Plains, Northern Prairie Pothole Region,New England Coastal Plain, and the Delmarva Penin-sula.

Because of funding limitations, only the first threegeographic areas were sampled during Fiscal Year1998. Sampling of the Delmarva Peninsula was fundedduring Fiscal Year 1999. The three geographic regionsselected for assessing wetland functions were theNorthern Prairie Pothole Region (NPPR); the Centraland Lower Mississippi Alluvial Valley (CLMV) com-posed of the Dissected Till Plains of the CentralLowland Province and the Mississippi Alluvial Valleywithin the Coastal Plain Province (Fenneman 1938);and the High Plains (HP) (fig. 1). For each geographicarea, a specific wetland HGM subclass was selected.

Selection was a function of predominance of wetlandsubclass impacted historically and currently by agri-cultural activities, as well as the subclass targetedmost frequently for restoration by NRCS via technicalassistance or USDA program dollars. Appendix Aprovides a description of the three geographic areassampled.

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Figure 1 Geographic areas selected for assessing wetland functional condition*

* Boundary of NPPR is approximate. Information used to depict geographic extent includes Major LandResource Areas, Land Resource Regions, and physiographic regions. USGS, Northern Prairie WildlifeResearch Center provided the Prairie Pothole Region coverage.

U.S. 48 States

High Plains

Lower Mississippi Alluvial Valley (MLRA 131)

Central Mississippi Valley (MLRA 115a)

Prairie Pothole Region

Northern Prairie Pothole Region

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Methods

Site selection

Approximately 15 (range: 5) sites targeted for restora-tion (referred to hereafter as restoration sites) as aresult of NRCS technical assistance or program fundswere selected from each HGM subclass. However,because of the extent of the Central and Lower Mis-sissippi Alluvial Valley (CLMV), regional physi-ographic differences and differences in local edaphic,vegetation, and restoration practices, the region wasdivided into two sampling areas. The upper portion,hereafter referred to as the Central Mississippi Valley(CMV), included Missouri (MO) and Illinois (IL; onesite), and the lower portion, known as the LowerMississippi Alluvial Valley (LMAV), included Arkansas(AR), Louisiana (LA), and Mississippi (MS).

Restoration sites were selected within the geographicrange of the subclass based on several factors. Theywere chosen to represent a range of ages (time sincerestoration initiated), geographic extent of the sub-class (where travel funds permitted), and a qualitativerange of restored conditions (those that appeared tobe functioning as well as those where physical andfunctional conditions were noticeably less than ex-pected or planned). Restoration sites ranged in meanage from 2 years for the LMAV, 4.5 years in the CMV,6.8 for the NPPR, and 10 years for the HP sites. Resto-ration sites were defined as areas that includedformer wetlands and where NRCS provided technicalassistance in accordance with National ConservationPractice Standard No. 657. Also included were siteswhere programmatic funds were used to enroll alandowner in a USDA conservation program thatdirectly or indirectly targeted wetland restoration(i.e., Wetland Reserve Program and ConservationReserve Program). No attempt was made to qualify asite as restored, as the NRCS Workgroup agreed thatrestoration is a continuing process that requires long-term monitoring until the site becomes self-sustain-ing. In addition, restoration sites funded under theWetland Reserve Program may also include somedegree of enhancement (USDA, NRCS 1996) as well asinclusion of an upland buffer that also often requiresrestorative treatment.

In addition to the wetlands undergoing restoration,approximately 15 (maximum 20, minimum 15) cultur-

ally altered and relatively unaltered wetlands (i.e.,reference sites) were also assessed for each of thethree HGM subclasses. Culturally altered wetlandsinclude naturally occurring wetlands that have beenmodified anthropogenically (hydrologically, chemi-cally, and biologically) to some extent but not sodegraded that they no longer exhibit wetland ecosys-tem functions. Those relatively unaltered wetlands arecharacterized by having intact hydrologic, chemical,and biological processes resulting in sustainablefunctional capacity. Many unaltered wetlands arerelicts of wetland systems that existed before Euro-pean colonization. A total of 118 restoration andreference sites were assessed for the three HGMsubclasses.

Reference sites were selected in a stratified randomfashion from the same HGM subclass as the restora-tion sites. Site selection factors included the variabil-ity of wetland condition of reference sites currentlyon the landscape, the range of anthropogenicallyaltered conditions present in each subclass, and thevariability associated with geographic locationswithin the sampled regions. Because of the smallsample size, the reference sites were not selected aspaired sites with the sample restoration sites, butwere proximate to the sample restoration sites. Thepurpose for sampling reference sites was to provide asnapshot of wetland condition on the landscape as awhole, but comprised of two subpopulations—resto-ration and reference sites. The method also provides atemplate for monitoring changes in wetland func-tional capacity at a landscape level.

Wetland functional assessmentprocedure

Wetland functions were assessed using HGM models(Smith et al. 1995) developed for each of the followingsubclasses: temporary and seasonal prairie potholewetlands of the NPPR; forested, low-gradient riverinewetlands in the CMV and LMAV; and playa wetlandsof the HP. Two of the three subclass models appliedwere developed as interim models by NRCS StateOffices for application of the Swampbuster provisionsof the 1985 Farm Bill, as amended (i.e., playa wet-lands and the forested, low-gradient riverine wet-lands). The interim models used to assess sites in the

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CMV and LMAV were adapted by NRCS from thosedeveloped for a Regional Guidebook addressingmature forested, low-gradient riverine wetlands inwestern Kentucky (Ainslie et al. 1999). The HGMmodels used to assess the temporary and seasonalprairie pothole wetlands of the NPPR are contained ina draft regional guidebook (Lee et al. 1997), also usedto apply “Swampbuster.” A list of the functions as-sessed for each subclass is presented in table 2.

Sites were assessed once during the 1998 growingseason by NRCS biologists and other professionalshaving expertise in wetland ecosystems. The HGMapproach was chosen as the functional assessmentmethod, as it provides a quantitative index (functionalcapacity index; FCI) that can be used to comparechange in wetland functional condition among wet-lands of the same subclass. Current site conditionswere used to assess the FCI for all 53 restoration sitesfor the three subclasses and represent conditions

after restoration was initiated (T1). Functional capac-ity index values for conditions before restoration, T0,were estimated based on the FCI values calculated foragriculturally altered sites included in the referencesites data set. The exception to this protocol was forthe LMAV, where T0 FCI values were independentlyestimated as the reference sites data set included onlymature forested, low-gradient riverine wetlands.Projected FCI values were calculated for an addi-tional 5 years beyond T1 (T2 through T5). Time peri-ods T1 through T5 roughly correspond to calendaryears 1999 through 2003. The future estimated FCIvalues were determined as part of the National Wet-land Functional Assessment Pilot to determine preci-sion in estimating FCI for future years as part of along-term monitoring effort. Only T1 and T0 FCIvalues are reported in this document.

The HGM models used are comprised of wetlandfunctions that generally equate to vegetation, hydrol-

Table 2. Functions assessed for three wetland hydrogeomorphic subclasses

Subclass Function

Seasonal and temporary Static surface water storageprairie potholes (NPPR) Dynamic surface water storage

Nutrient cyclingRemoval of imported elements and compoundsRetention of particulatesProvide environment for characteristic plant communityHabitat structure within wetlandHabitat interspersion and connectivity among wetlands

Forested, low-gradient Temporary storage of surface waterriverine wetlands Retention and retarding the movement of ground water(CMV and LMAV) Cycling of nutrients

Removal and sequestration of elements and compoundsRetention of particulatesOrganic carbon exportProvide environment for native plant communityPromote wildlife habitat

Playa wetlands (HP) Maintain characteristic static or dynamic storage, soil moisture, andground water interactions

Elemental cycling and retention of particulatesPlant communityFaunal habitat, food webs, and habitat interspersion

7



ogy, wildlife, and biogeochemical functions. Eachfunction is constructed of two or more variables thatare either directly measured or indirectly measuredusing a surrogate for the variable. A subindex score isdetermined for each variable. An FCI for each func-tion is derived from the mathematical relationshipamong the variables and the subindex scores calcu-lated for each variable. The FCI ranges from 0.00 to1.00. An FCI of 1.00 represents the highest sustainablefunctioning capacity for any given function in a wet-land (sustainable functional condition). FCI valuesare determined independently for each function, andfunctions are not interchangeable among wetlandsubclasses. For example, while a hydrologic functionmay be measured for temporary and seasonal prairiepothole wetlands and forested, low-gradient riverinewetlands, the specific variables measured will likelydiffer because the differences in geomorphic settingand the hydrodynamics of each subclass. Variables forthe hydrologic function of each subclass are thereforealso different, as is the scoring of the variables todetermine the subindex score (Hauer and Smith1998). A table listing each function by subclass, theequation used to calculate the functional capacityindex for each function, and a description of thevariables used in each functional equation appear inappendix B.

Statistical analysis

Because of the small sample size, statistical tests fordifferences among sites and between time periods(before and following restoration, T0 and T1 respec-tively) within a subclass were not conducted. Descrip-tive statistics (mean, maximum, minimum, and vari-ance of FCI values) were calculated for each restoreddata set for each subclass. Because of the variabilityencountered in the reference sites, median valueswere calculated for both the reference sites andrestored wetlands to compare condition of referenceand restoration sites at a broad scale for each sub-class. The wetland median FCI values of the referencesites were calculated for current conditions only, andwere compared to the T1 FCI median values calcu-lated for the restoration sites. Where the data allowed,analysis of age or vegetation stage was also con-ducted for the wetland subclasses. In addition, be-cause of differences in restoration techniques in theMississippi Valley, an analysis was conducted com-paring the results in the CMV to those in the LMAV.

Results

Temporary and seasonal prairiepothole wetlands, NorthernPrairie Pothole Region

Restoration sites

Eight wetland ecosystem functions were measuredfor 13 restoration sites (table 2). The change in meanFCI between T0 and T1 for each function is shown intable 3. Restoration site FCI values for each functionat T0 and T1 are in appendix C, figures 1 – 8. Thechange in mean FCI differed among functions, withthe Retention of particulates function exhibiting thegreatest mean FCI change. The Provide environment

for characteristic plant community function had thesmallest mean FCI change between T0 and T1. Ingeneral, the functional capacity of restored temporaryand seasonal prairie pothole wetlands sampled in theNPPR increased overall.

Functional capacity of the restoration sites was mark-edly different within and between sites and amongfunctions. Before restoration, three restoration siteshad calculated site FCI’s of 0.00 for the Static water

storage function compared to all 13 restoration siteshaving FCI’s of 0.00 at T0 for the Dynamic water

storage function (app. C, figs. 1 and 2). At T1, the 13restoration sites exhibited some functional capacityincrease in the Static water storage function, but anFCI of 0.00 was calculated for the Dynamic surface

water storage function for four of the 13 restorationsites after restoration was initiated.

Changes in mean FCI values varied for the threebiogeochemical functions measured (table 3). Therewas a comparable increase of the FCI values for theNutrient cycling and removal of imported elements

and compounds functions (0.41 and 0.44 mean FCIincrease, respectively). However, the change in FCIwas greatest for the Retention of particulates func-tion (0.63 mean FCI increase) (table 3).

The mean FCI value at T0 for the Provide environ-

ment for characteristic plant community functionwas 0.28, and at T1 it was 0.68, an increase of 0.40(table 3). The mean FCI values for the two wildlifehabitat functions measured also increased. The meanFCI value for the Habitat structure within wetland

8



Table 3. Change in mean FCI (T1 – T0) for each function within a subclass

Subclass Function T0 T1 Mean change

Temporary and seasonal prairie Static surface water storage 0.20 0.74 0.54pothole wetlands, NPPR Dynamic surface water storage 0.00 0.57 0.57

Nutrient cycling 0.23 0.64 0.41Removal of imported elements and compounds 0.25 0.70 0.45Retention of particulates 0.10 0.73 0.63Provide environment for characteristic plant 0.28 0.68 0.40

communityHabitat structure within wetland 0.15 0.71 0.56Habitat interspersion and connectivity among 0.31 0.78 0.47

wetlands

Forested, low-gradient Temporary storage of surface water 0.59 0.59 0.00riverine wetlands, LMAV Retention and retarding the movement of 0.41 0.41 0.00(AR, LA, MS) ground water

Cycling of nutrients 0.33 0.46 0.13Removal and sequestration of elements and 0.73 0.73 0.00

compoundsRetention of particulates 0.59 0.59 0.00Organic carbon export 0.31 0.40 0.09Provide environment for native plant 0.25 0.37 0.12Promote wildlife habitat 0.53 0.56 0.03

community

Forested, low-gradient Temporary storage of surface water 0.37 0.38 0.01riverine wetlands, CMV Retention and retarding the movement of 0.65 0.74 0.09(MO) ground water

Cycling of nutrients 0.26 0.41 0.15Removal and sequestration of elements and 0.55 0.61 0.06

compoundsRetention of particulates 0.37 0.38 0.01Organic carbon export 0.21 0.35 0.14Provide environment for native plant 0.29 0.43 0.14

communityPromote wildlife habitat 0.39 0.45 0.06

Playa wetlands, Maintain characteristic static or dynamic 0.60 0.81 0.21 High Plains (KS) storage, soil moisture, and ground water

interactionsElemental cycling and retention of particulates 0.43 0.73 0.30Plant community 0.37 0.69 0.32Faunal habitat, food webs, and habitat 0.23 0.68 0.45

interspersion

9



function increased from 0.15 at T0 to 0.71 at T1. SiteFCI values, however, ranged from 0.06 to 0.25 at T0and 0.31 to 0.84 at T1 (app. C, fig. 7). The habitatfunction addressing the spatial relationship among thewetland under assessment and adjacent wetlandswithin the complex, Habitat interspersion and con-

nectivity among wetlands, increased in mean FCIfrom 0.31 to 0.78, an increase in mean FCI of 0.47(table 3). Site FCI values ranged from 0.18 to 0.53 atT0. At T1, site FCI values ranged from a low of 0.42 toa high of 0.96 (app. C, fig. 8).

Reference sites vs. restoration sites

Fifteen reference sites were assessed using the samefunctions assessed for the restoration sites (table 2).The median FCI for temporary and seasonal prairiepothole wetland reference sites sampled in the NPPRwas compared to that for the restored wetlands foreach function. Results of this comparison indicatethat the reference sites wetlands exhibited a highermedian FCI value than the restoration sites for five ofthe eight functions assessed (table 4). The differencesdo not appear significant, except for the Removal of

imported elements and compounds function. Onlyone reference site sampled exhibited a sustainableFCI for seven of the eight functions assessed (FCI =1.00).

Forested, low-gradient riverinewetlands, LMAV (AR, LA, MS)

Restoration sites

Mean FCI values were calculated for eight ecosystemfunctions (table 2) for 15 restoration sites in Arkan-sas, Louisiana, and Mississippi that fall within theLMAV. The change in mean FCI between T0 and T1for each function is shown in table 3. Site FCI valuesat T0 and T1 are in appendix C, figures 9 to 16 foreach function. Neither of the functions involvinghydrologic dynamics and modification of offsite andonsite hydrology changed before or after restorationwas initiated. FCI site values ranged from a minimumof 0.27 to a maximum of 0.74 for the Temporary

storage of surface water function (app. C, fig. 9). Themean FCI at T0 and T1 was 0.59, with this functionremaining relatively unchanged before and afterrestoration was initiated (table 3). A site FCI of 1.00,the highest sustainable functional index value attain-able in the model, was assessed for the Subsurface

water storage function at 2 of the 15 sites at T0 and T1(app. C, fig. 10). The remaining 13 sites have T0 and T1FCI values of 0.32.

Four functional models intended to measure thecapacity of a wetland to perform various bio-geochemical processes were used to derive FCI val-ues. A slight increase in mean FCI was calculatedbetween T0 and T1 for the Nutrient cycling function,with a change in mean FCI from 0.33 to 0.46. Therewas no change in mean FCI (0.73) calculated for theRemoval and sequestration of elements functionbefore and after restoration. Similarly, there was nochange between T0 and T1 for the Retention of par-

ticulates function with mean FCI values of 0.59 at T0and T1 (table 3). There were differences, however,among site FCI values (max 0.74; min 0.27; app. C, fig.13). Mean FCI at T0 was 0.31 and 0.40 at T1 for theOrganic carbon export function, a net change of 0.09(table 3). There was also variation among site FCIvalues for this function, with minimum values at T0and T1 of 0.26 and 0.29, respectively, and maximumvalues ranging from 0.32 to 0.73, respectively (app. C,fig. 14).

The mean FCI calculated for the Maintenance of

native plant communities function at T0 was 0.25and at T1 it was 0.37, a net change of 0.12 (table 3).The change in FCI varied among sites, with some sitesshowing no change in the calculated FCI between T0and T1 (app. C, fig. 15). The function, Maintenance of

habitat support, showed little change in mean FCIbetween T0 and T1, 0.53 and 0.56, respectively (table3). Site FCI values for this function ranged fromminimum values of 0.51 and 0.52 at T0 and T1 tomaximum values of 0.56 and 0.60 at T0 and T1, re-spectively (app. C, fig. 16).


All eight ecosystem functions were assessed and FCIvalues calculated for 15 reference sites. The referencesites data set in this portion of the LMAV consisted ofmature bottomland hardwood (BLH) wetlands, withthe average age approximated at 60 to 65 years. Gen-erally, the median FCI values for each function as-sessed were greater for the reference sites than thosecalculated for the restoration sites (table 4). Theexception was for the Subsurface water storage

function, where there was no difference between thereference and restoration site median FCI values.

10



Table 4. Comparison between reference and restoration site median FCI values for functions sampled in three wetlandhydrogeomorphic subclasses

Subclass Function Reference Restoredsites sites

Temporary and seasonal Static surface water storage 0.82 0.79prairie pothole wetlands, Dynamic surface water storage 0.75 0.79NPPR Nutrient cycling 0.58 0.68

Removal of imported elements and compounds 0.80 0.69Retention of particulates 0.81 0.75Provide for characteristic plant community 0.78 0.71Habitat structure within wetland 0.76 0.75Habitat interspersion and connectivity among wetlands 0.58 0.79

Forested, low-gradient Temporary storage of surface water 0.94 0.69riverine wetlands, LMAV Retention and retarding the movement of ground water 0.32 0.32 (AR, LA, MS) Cycling of nutrients 0.78 0.48

Removal and sequestration of elements and compounds 0.86 0.74Retention of particulates 0.94 0.69Organic carbon export 0.98 0.38Provide environment for native plant community 0.71 0.35Promote wildlife habitat 0.62 0.56

Forested, low-gradient Temporary storage of surface water 0.42 0.42riverine wetlands, CMV Retention and retarding the movement of ground water 1.00 1.00(MO, IL) Cycling of nutrients 0.50 0.44

Removal and sequestration of elements and compounds 0.80 0.74Retention of particulates 0.42 0.42Organic carbon export 0.27 0.32Provide environment for native plant community 0.50 0.43Promote wildlife habitat 0.56 0.40

Playa wetlands, the High Maintain characteristics static or dynamic storage, 0.75 0.80 Plains (KS) soil moisture, and ground water interactions

Elemental cycling and retention of particulates 0.73 0.73Plant community 0.86 0.68Faunal habitat, food webs, and habitat interspersion 0.58 0.70

11



Forested, low-gradient riverinewetlands, CMV (MO, IL)

Restoration sites

The same HGM models applied in the LMAV wereapplied in the CMV (table 2). Site FCI values at T0 andT1 for each function are in appendix C, figures 17 to24. A slight increase in mean FCI was calculated forthe Temporary storage of surface water function(table 3). Site FCI values did not change between T0and T1 for 13 of the 15 restoration sites (app. C, fig.17). There was an increase in the mean FCI for theSubsurface water retention function (table 3), withthe increase derived from 2 of the 15 restoration sites(app. C, fig. 18). Site FCI values for this functionremained the same at T0 and T1 for the 13 remainingrestoration sites.

Change in functional capacity for the four bio-geochemical functions assessed varied by functionand among sites. The mean FCI increased for theNutrient cycling function from 0.26 to 0.41 (table 3),with all sites except one showing some increase inFCI from T0 (app. C, fig. 19). An increase in mean FCIwas calculated for the Removal and sequestration of

elements function (table 3). Four of the 15 restorationsites have an increase in site FCI and the FCI valuesfor the remaining sites showed no change in site FCIfor this function between T0 and T1 (app. C, fig. 20). Aslight increase in mean FCI was calculated for theRetention of particulates function, from 0.37 to 0.38(table 3). Two of the 15 restoration sites showed anincrease in site FCI, and the remaining 13 sitesshowed no change in site FCI (app. C, fig. 21). SiteFCI values for the Organic carbon export functionalso varied, ranging from 0.06 to 0.32 at T0 and 0.06 to0.74 at T1. Ten of the 13 sites showed an increase insite FCI (app. C, fig. 22). The mean FCI for this func-tion was 0.21 at T0 and 0.35 at T1, a net increase of0.14 (table 3). The Organic carbon export and Nutri-

ent cycling functions showed the greatest change inFCI of the four biogeochemical functions as well asthe remaining functions for restoration sites in thiswetland subclass.

An increase in mean FCI was calculated for the Na-

tive plant community support function (table 3).Thirteen of the 15 restoration sites had a site FCIincrease, with FCI values ranging from 0.21 to 0.46 atT0 and from 0.27 to 0.62 at T1 (app. C, fig. 23). MeanFCI increased from 0.39 to 0.45 for the Wildlife habi-

tat function (table 3), with all but one site showing aslight increase in site FCI values (app. C, fig. 24).


Similar to the sampling of the reference sites in theLMAV, 14 sites were selected in Missouri and one inIllinois within the CMV in close proximity to therestoration sites. The sites used to construct thereference site data set for the CMV consisted of ma-ture BLH wetlands, early succession BLH wetlandsdominated by shrub or herbaceous vegetation, andfarmland and prior-converted wetlands under cultiva-tion. The results show that the median FCI for thereference sites was higher than that for the restora-tion sites for four of the eight functions in the CMV(table 4). Three of the functions exhibited the samemedian FCI for restoration and reference sites. Inaddition, the median FCI value was lower for theExport of organic carbon function for reference sitescompared to the restoration sites. However, this valuechanges when the reference sites are classified byvegetation structure. The mature reference sitesexhibit the highest median FCI value (see discussionsbelow and tables 4 and 6.

These results are different than those in the LMAV(table 4). Additional analysis shows that generallythere is a greater difference between the referencesite and restoration site median FCI values in theLMAV than between those in the CMV, with the no-table exception of the Maintenance of wildlife habi-

tat function (table 5). The difference may reflect siteage, restoration techniques, selection of referencesites and vegetation structure, connectivity to othersites, lack of model sensitivity, or different interpreta-tion of the same models by the two sampling teams.

To determine whether the disparity in median func-tional capacity index values between the CMV andLMAV could be further explained by differences invegetation successional stage, the CMV referencesites data set was divided into three groups: Agricul-turally altered wetlands, Early successional wetlands,and Mature bottomland hardwood wetlands. Themedian FCI values for each function were calculatedfor each group and qualitatively compared to themedian FCI value for the restoration sites for theeight functions. The comparison indicates that themedian FCI values for the restoration sites were moresimilar to those calculated for the early successionalsites for three of the eight functions (Nutrient cy-

12



cling, Native plant community support, and Wildlife

habitat support) (table 6). Median FCI values forrestoration sites and agriculturally altered sites werethe same for the Temporary storage of surface water,Subsurface water retention and retardation, Re-

moval and sequestration of elements, and Retention

of particulate functions. The median FCI values forthe Export of organic carbon function was similar butnot the same between the restoration and agricultur-ally altered sites.

A comparison was also made between the median FCIvalues for the mature bottomland hardwood referencesites wetlands in the CMV and LMAV (table 7). Themedian FCI values were lower for three of the fourbiogeochemical functions assessed for the mature

BLH reference sites in the CMV than in the LMAV.The lower median FCI for the Cycling of nutrients

function may be, in part, the result of younger standage in the Missouri and Illinois sites. Average basalarea (i.e., cross-sectional area of trunks measured ata standard height), an often-used surrogate of forestmaturity, for the sites in Missouri and Illinois was 8.24square meters. The average basal area for AR, LA, andMS was 13.39 square meters. Median FCI values forthe Native plant community support and Wildlife

habitat support functions were somewhat higher,however, for the Missouri/Illinois mature BLH refer-ence sites, indicating that nonbiotic or landscapespatial variables scored higher for these functions inthe CMV than in the LMAV. The CMV mature refer-ence sites show a sustainable median FCI for the

Table 5. Comparison of differences in median FCI values between the CMV (MO) and LMAV (AR, LA, MS) restoration andreference sites

Function CMV LMAV

Temporary storage of surface water 0.00 0.25Retention and retarding the movement of ground water 0.00 0.00Cycling of nutrients 0.06 0.30Removal and sequestration of elements and compounds 0.06 0.12Retention of particulates 0.00 0.25Organic carbon export * *Provide environment for native plant community 0.07 0.35Promote wildlife habitatat 0.16 0.06

* Because the median FCI for the restoration sites was greater than for the reference sites in the CMV, a direct comparison for this functionis not appropriate.

Table 6. Comparison of median FCI values among vegetation stages for reference and restoration sites, CMV (MO).

Function Agriculturally Early Mature Restorationaltered sites successional forested sites

Temporary storage of surface water 0.42 0.32 0.56 0.42Retention and retarding the movement of ground water 1.00 0.66 1.00 1.00Cycling of nutrients 0.10 0.56 0.58 0.44Removal and sequestration of elements and compounds 0.74 0.39 0.88 0.74Retention of particulates 0.42 0.32 0.56 0.42Organic carbon export 0.25 0.18 0.87 0.32Provide environment for native plant community 0.32 0.51 0.85 0.43Promote wildlife habitat 0.17 0.63 0.70 0.40

13



ground water storage function (table 7) that mayindicate a significant difference between the mediumFCI values for this function.

Playa Wetlands, the High Plains (KS)

Restoration sites

Six wetland ecosystem functions were assessed for 10restoration sites within the HP of Kansas (table 2).The change in mean FCI between T0 and T1 for eachfunction is shown in table 3. Site FCI values at T0 andT1 are shown in appendix C, figures 25 – 28. Func-tional capacity increased for all four groups of func-tions (table 3). Mean FCI increased from 0.60 at T0 to0.81 at T1 for the Maintains characteristic hydro-

logic regime function, a net increase of 0.21 (table 3).Site FCI values ranged from 0.55 to 0.70 at T0 andfrom 0.70 to 1.00 at T1 (app. C, fig. 25). Site FCI valuesranged from 0.33 to 0.60 at T0 for the two biogeochemicalfunctions assessed (Maintains elemental cycling andRetention of particulates).

At T1, site FCI values ranged from 0.63 to 0.93 (app. C,fig. 27). The mean site FCI change was 0.30 for thetwo functions (table 3). The mean FCI increased from0.37 to 0.69 for the Maintains characteristic plant

community function, the second greatest increase inmean FCI of the four functional groups assessed forthis wetland subclass (table 3). The Wildlife func-tional group, addressing within wetland habitat struc-ture, food web support, and habitat interspersion andconnectivity among wetlands, showed the greatestincrease in mean FCI values, increasing from 0.23 to

0.68 for a net FCI change of 0.45 (table 3). It was alsothe functional group with the lowest mean FCI valuecalculated after restoration was initiated.


Twenty reference sites were assessed using the samefunctions assessed for the restoration sites. Thetwenty sites were comprised of 10 farmed playawetlands and 10 nonfarmed playa basins. When allreference sites are combined, only the plant commu-nity function median FCI is lower for the restorationsites (table 4). The median FCI value for the bio-geochemical functions is the same.

When the reference sites data set, however, is sepa-rated into farmed and nonfarmed and is compared tothe restoration sites, the median FCI values for thehydrologic regime and the plant community functionswere similar between the nonfarmed playa wetlandsand the restoration sites (table 8). For the remainingtwo functional groups, the median FCI values for therestoration sites were intermediate between thenonfarmed playa wetlands and the agriculturallyaltered playa wetlands (table 8).

Table 7. Comparison of median FCI values between CMV (MO) and LMAV (AR, LA, MS) mature forested, low-gradientriverine reference sites.

Function CMV* LMAV**

Temporary storage of surface water 0.56 0.94Retention and retarding the movement of ground water 1.00 0.32Cycling of nutrients 0.58 0.78Removal and sequestration of elements and compounds 0.88 0.86Retention of particulates 0.56 0.94Organic carbon export 0.87 0.98Provide environment for native plant community 0.85 0.71Promote wildlife habitat 0.70 0.62

* Median FCI values calculated from 6 reference sites.** Median FCI values calculated from 15 reference sites.

14



Discussion

The results from this pilot demonstrate that, using theavailable interim and regional guidebook HGM mod-els as the assessment methods, there was an increasein wetland functional capacity index values for mostfunctions assessed at the sample restoration sites forthe three wetland subclasses. However, the resultsalso indicate that the mean functional capacity indexfor each subclass function lies well below that identi-fied as the highest sustainable functional capacity(i.e., 1.00). Proportioning individual site FCI values atT1 for each subclass function also shows that a smallpercentage of sites achieved an FCI of 1.00 for justone function (table 9).

Although some sites may eventually achieve a sustain-able functional capacity for all functions characteris-tic of a subclass, others may never achieve this levelover the short or long term. Several possible reasonsfor this—vegetation structure of restoration site;degree, type and frequency of landscape alterations;and HGM model refinement and validation—arediscussed below. Other reasons such as restorationtechniques applied and landowner management goalsfor the site also play a role. The type of restorationtechniques and degree to which they were appliedundoubtedly affect functional capacity levels.

This study was not designed nor intended to evaluateeffectiveness of site design or implementation. How-ever, data derived from this study indicates an evalua-tion of successful restoration techniques appropriate

to a wetland subclass is critically necessary to achieveand maintain sustainable functional conditions. Peri-odic evaluation of restoration techniques is a neces-sary component to successful restoration implementa-tion and should be conducted routinely as required byNational Conservation Practice No. 657 (WetlandRestoration operation and maintenance standards).

The Conservation Practice also requires a pre- andpost-assessment of the target restoration site, and useof the HGM or a similar assessment procedure. How-ever, the HGM models or other similar assessmentmethod used must be developed in such a way thathistoric as well as current landscape conditions areassessed. An assessment of the extent to which an-thropogenic alterations have changed the landscapesince historic times can determine whether sustain-able functional capacity is even achievable or canprovide a reference to require special restorationtechniques to address alterations caused by historicor current land use practices.

Landowner preferences as to the type of wetlandsubclass that eventually results and the concerns ofadjacent landowners with hydrologic restoration arealso factors that influence recovery to a sustainablefunctional condition. One or both of those factors cannegate successful functional restoration of specificwetland subclasses and result in a costly project witha high maintenance requirement. A better understand-ing of the wetland subclass, and what societal valuesa landowner may receive through restoration of thatsubclass, is a necessary precursor to achieving suc-cessful restoration of any wetland subclass.

Table 8. Comparison of median functional capacity index values among restoration sites, reference sites, and agricultur-ally altered playa wetlands, the High Plains (KS)

Function Agriculturally Nonfarmed Restorationaltered playas playas sites

Maintain characteristic static or dynamic storage, soil moisture, and ground water interactions 0.66 0.85 0.80Elemental cycling and retention of particulates 0.48 0.97 0.73Plant community 0.48 0.96 0.68Faunal habitat, food webs and habitat interspersion 0.31 0.75 0.70

15



Table 9. Percentage of restoration sites grouped by functional capacity index value categories at T1

Subclass Function . . . . . . . . . .. . . . .Percent sites with functional capacity index at . . . . . . . .. . T1 = 1.00 T1 > 0.75 T1 > 0.50 T1 > 0.25 T1 > 0.10 T1 < 0.10

< 1.00 < 0.75 < 0.50 < 0.25

Temporary and Static surface water storage 0.0 69.2 23.1 7.7 0.0 0.0 seasonal Dynamic surface water storage 0.0 61.5 7.7 0.0 0.0 30.8 prairie pot- Nutrient cycling 0.0 23.1 61.5 15.4 0.0 0.0 holes, NPPR Removal of imported elements 0.0 38.5 53.8 7.7 0.0 0.0

and compoundsRetention of particulates 0.0 76.9 15.4 0.0 7.7 0.0Provide for characteristic plant 0.0 30.8 69.2 0.0 0.0 0.0

communityHabitat structure within wetland 0.0 61.5 31.8 7.7 0.0 0.0Habitat interspersion and 0.0 76.9 15.4 7.7 0.0 0.0

connectivity among wetlands

Forested, Temporary storage of surface water 0.0 0.0 73.3 26.7 0.0 0.0 low-gradient Retention and retarding the move- 13.3 0.0 0.0 86.7 0.0 0.0 riverine wet- ment of ground water lands, LMAV Cycling of nutrients 0.0 0.0 0.0 100.0 0.0 0.0

Removal and sequestration of 0.0 0.0 100.0 0.0 0.0 0.0elements and compounds

Retention of particulates 0.0 0.0 73.3 26.7 0.0 0.0Organic carbon export 0.0 0.0 13.3 86.7 0.0 0.0Provide environment for native 0.0 0.0 20.0 60.0 20.0 0.0

plant communityPromote wildlife habitat 0.0 0.0 100.0 0.0 0.0 0.0

Forested, Temporary storage of surface water 0.0 0.0 26.7 46.7 26.7 0.0 low-gradient Retention and retarding the 60.0 0.0 6.7 26.7 6.7 0.0 riverine wet- movement of ground water lands, CMV Cycling of nutrients 0.0 0.0 20.0 60.0 20.0 0.0

Removal and sequestration of 0.0 46.7 20.0 6.7 0.0 26.6elements and compounds

Retention of particulates 0.0 0.0 26.7 46.7 26.7 0.0Organic carbon export 0.0 0.0 26.7 33.3 33.3 6.7Provide environment for native 0.0 0.0 26.7 73.3 0.0 0.0

Plant communityPromote wildlife habitat 0.0 0.0 33.3 66.7 0.0 0.0

Playa wet- Maintain characteristic static or 100.0 70.0 20.0 0.0 0.0 0.0 lands, High dynamic storage, soil moisture, Plains and ground water interactions

Elemental cycling and retention 0.0 20.0 80.0 0.0 0.0 0.0of particulates

Plant community 100.0 100.0 80.0 0.0 0.0 0.0Faunal habitat, food webs, and 0.0 20.0 70.0 100.0 0.0 0.0

habitat interspersion

16



Restoration site vegetation structure

Kusler and Kentula (1989) hypothesized that restoredwetlands will functionally rebound at a relatively fastrate, and certainly faster than created wetlands. Inaddition, herbaceous wetlands, such as prairie pot-hole and playa wetlands, may exhibit a faster rate offunctional change than sites targeted for forestedwetland restoration. Comparative data on rate offunctional capacity restoration relative to the dominantwetland vegetation life form is lacking for this study.

Data from the study, however, can be used to com-pare mean FCI values between wetlands of similarages dominated by woody and herbaceous vegetationfor the nutrient cycling function. This function iscommon to all subclasses sampled. An analysis indi-cates that at T1, the mean FCI values are similar forherbaceous (NPPR) and woody (LMAV, MO) restora-tion sites which are 1 to 2 years of age (table 10).However, the herbaceous restoration sites that arefrom 5 to 8 years of age at T1 have a mean FCI valueof 0.71 compared to a mean of 0.39 for woody restora-tion sites which are 5 to 6 years of age at T1.

Other variables, such as soil structure, influence thecalculation of the FCI for this biogeochemical func-tion. This example illustrates, however, that vegeta-tion structure is an important consideration whenmonitoring changes in functional condition for differ-ent wetland subclasses. Wetlands dominated bywoody vegetation (forested and scrub-shrub wetlands)will often take more time to yield high FCI levels.

The wetland restoration strategy in the LMAV is toreturn cleared agricultural lands to what were histori-cally mature forested wetlands. As such, many of theHGM model variables measured are indicators ofmature forested wetland systems, not the young(those that have a mean age of 4.5 years in Missouriand 2 years in Arkansas, Louisiana, and Mississippi)sapling- and herbaceous-dominated wetlands thatcomprise the restoration wetlands. It will take manyyears—perhaps 60 or more years—for conditionssimilar to mature forested, low-gradient riverinewetlands to develop.

Site index values for several tree species common tothe forested, low-gradient riverine restoration sitesare shown in table 11. These values show the poten-

tial productivity of soil characteristic of these wetlandsystems to support the growth of these species and,theoretically, the restoration of forested, low-gradientriverine wetland systems. However, the ability of thesoil to support these species, and eventually thewetland systems, depends in large measure on thedegree to which soil structural and chemical charac-teristics have been modified through cropping practices.

Although the current absence of mature forestedwetlands results in less than sustainable FCI valuesfor the Central and Lower Mississippi Valley, thelocation of restoration sites funded by the WetlandReserve Program (WRP) may be a contributing factorto the long-term conservation of forest-breedinglandbirds in the region. The USGS, Biological Re-sources Division and the U.S. Fish and Wildlife Ser-vice, Lower Mississippi River Joint Venture, Vicks-burg, Mississippi, have developed a geospatial modelthat identifies reforestation habitat priorities forforest-breeding landbirds in the Mississippi AlluvialValley (MAV) (Twedt and Uihlein 1999). One of theobjectives in developing the model was to “assess theperformance of recent enrollments in the [WRP] withregard to their location relative to priority reforesta-tion habitat.” Approximately 40 percent of WRP landsenrolled in the MAV that were digitally available at thetime or could be digitally created in a short period formodel use were included in the analysis.

Results showed that, with the limited spatial WRPdata available at the time, the distribution of WRPacreage was in the higher reforestation priorities(Twedt and Uihlein 1999). Eighty-eight percent ofWRP lands were above the average priority categoryfor the MAV and 57 percent were distributed in thehighest three reforestation priority categories. Thehigh percent of land in the highest reforestationpriorities is likely the result of the spatial juxtaposi-tion of WRP land and adjacent existing forest (Twedtand Uihlein 1999). Although this information does notspecifically address the forested, low-gradient riverinesubclass, approximately 55 percent of WRP land inMississippi, Louisiana, and Arkansas may be in thissubclass.1

Data from the geospatial model shows that the great-est amount of acreage in Mississippi and Arkansas is

1/ Estimate is not derived from documentation but basedon estimation by NRCS.

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Table 10. Comparison of mean FCI values over time for nutrient cycling function,herbaceous (NPPR) and forested (LMAV, MO/IL) restoration sites

Vegetation type Age T1 Age T1

Herbaceous 1 0.50 7 0.68(NPPR) 1 0.36 7 0.68

2 0.30 8 0.788 0.688 0.718 0.72

0.39 (mean) 0.71 (mean)

Forested 1 0.45 5 0.54(CMV-MO/IL) 2 0.36 5 0.22

2 0.45 6 0.412 0.44 6 0.292 0.48 6 0.21

6 0.246 0.456 0.406 0.516 0.64

0.44 (mean) 0.39 (mean)

TABLE 11. Site index range for tree species common to soil of the forested,low-gradient riverine subclass, CMV and LMAV

Common name Scientific name Site Index Range(height in feet)

Eastern cottonwood Populus deltoides 90-120Tulip poplar Liriodendron tulipifera 115Sweet gum Liquidambar styraciflua 90-110Water oak Quercus nigra 90-110Texas red oak Quercus texana 90-110Shumard’s oak Quercus shumardii 105Cherrybark oak Quercus pagoda 90-100Willow oak Quercus phellos 90-100Loblolly pine Pinus taeda 90-95Pin oak Quercus palustris 80-100Green ash Fraxinus pennsylvanica 78-100American sycamore Platanus occidentalis 80

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distributed in the Moderate Priority, Priority, andModerately High Priority reforestation categories.Acreage in Louisiana is highest in the Priority, Moder-ately High Priority, and High Priority reforestationcategories. The distribution of acreage in Missouri isgreatest in the lower reforestation categories (Twedtand Uihlein 1999). Although the state acreage distribu-tions are not limited to just WRP land, they do providea broader context in which to evaluate restoration offorested wetland relative to breeding landbirds. Anupdated digital WRP layer could enhance the findingsfrom this initial analysis and provide a more robustanalysis of the contribution of WRP to breedinglandbird conservation in the MAV. Additionally, col-laboration with the U.S. Fish and Wildlife Service’sMAV Joint Venture and the Biological ResourcesDivision of the USGS could also involve developing asuite of geospatial models that identify multiplelandscape features to assist in restoration of the MAVas a functioning landscape.

Landscape alteration

Landscape alteration is one of the most insidiousfactors responsible for change in wetland extent andfunction. The most current wetland trends, derivedfrom the 1997 National Resources Inventory (NRI),show a net change in wetland extent of approximately65,934 hectares during this period (USDA, NRCS2000a). Gross acreage losses were highest in theSoutheast, South Central, and Midwest NRCS admin-istrative regions, although the overall net acreagechange during this period shows that the Southeast,East, and Midwest are still experiencing the highestnet acreage losses (fig. 2).2

2/ The net change in wetland extent for each region includesstates and wetland subclasses other than those sampled. Arkansas,Louisiana, and Mississippi are included in the South Central andSoutheast Regions, respectively. Missouri and Illinois are in theMidwest Region. The Northern Plains Region includes NorthDakota and Kansas.)

-75000 -60000 -45000 -30000 -15000 0 15000 30000

Southeast

East

Ha

West

South Central

Northern Plains

Midwest

Figure 2. Net change in wetland extent between 1992 and 1997 within NRCS administrative regions*

* See text for states associated with a particular region of interest to this study. Error bars represent the 95% confidence interval. Confi-dence intervals for the Northern Plains, West and South Central regions are wider than estimates because they include 0, hence the netchange may not be different than 0 (USDA, NRCS 2000a).

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These areas historically had extensive Palustrinewetlands, a type of wetland that includes the HGMwetland subclasses sampled. Palustrine wetlandscontinue to dominate the landscape, accounting foralmost 95 percent of wetlands sampled by the 1997NRI. Of the 42.8 million hectares of Palustrine wet-lands in the conterminous United States, 10.3 millionoccur on cropland, pastureland, and rangeland (table12). These wetlands have been and continue to beexposed to a range of anthropogenic activities thatmodify the landscape, resulting in significant effectson their ability to maintain or achieve a high sustain-able functional condition.

Similar to other Palustrine wetlands, the three HGMsubclasses sampled have been impacted by anthropo-genic activities, particularly agricultural activities.Many of these wetland systems have been drained,ditched, chemically altered, or otherwise manipulatedto provide suitable conditions to conduct traditionalagricultural practices. The surrounding landscapeshave been altered from a matrix of native forest orprairie to one of intensive agrosystems, with subse-quent changes in hydrologic and nutrient pathways,increased erosion, introduction of contaminants, andfragmentation of the wetland-landscape interface.Such changes in the historic, pre-European landscapehave resulted in wetland acreage losses, functionalimpairment, and degraded ecosystem conditions. Thechallenge to restore wetland ecosystems is to recog-nize that the landscapes in which these systems areembedded have been drastically altered and thatrestoration must involve not only changes to condi-tions within the wetland but also in land practicesbeyond the wetland itself. In many cases, restorationsites may never achieve their highest sustainable

functional capacity because landscape alterations arelikely to continue in the foreseeable future.

Temporary and seasonal prairie pothole

wetlands, NPPR

The existing hydrologic models for temporary andseasonal prairie pothole wetlands in the NPPR math-ematically emphasize the importance of surface waterelevation in measuring functional capacity for anygiven wetland. The less-than-sustainable FCI valuesfor the hydrology functions assessed indicate that theoriginal hydrology has not returned following restora-tion activities. Although almost 62 percent of theprairie pothole restoration sites exceed the meanfunctional capacity value of 0.74, none of the sitesexhibited a sustainable functional capacity value forthe Static surface water storage function. The rela-tively lower mean functional capacity value of 0.57 forthe Dynamic surface water storage function alsoindicates that hydrologic modifications have ham-pered hydrologic recovery to a sustainable functionalcapacity level.

The inability to achieve a sustainable functionalcapacity in the sampled restoration sites is due to thelow scoring of the variable associated with wetlandoutlet elevation for both of these hydrology functions(ditches were plugged, but outlets were not restoredto preexisting topography). The ability of the restora-tion sites to hold water under either static or dynamicsurface water conditions was therefore adverselyaffected (Rodney O’Clair, NRCS, North Dakota StateOffice, and Michael Whited, NRCS, Wetlands ScienceInstitute, personal communications).

Closely linked to the effect of outlet elevation onrecovery of sustainable hydrologic conditions inrestored wetlands is past and current land use. Al-though planted grasslands currently buffer all of therestoration sites sampled, the previous land use wasagriculture. Cultivation in the surrounding uplandsaccelerates erosion and sediment deposition into thebasin wetland (Gleason and Euliss 1998; Martin andHartman 1986) as a result of increases in surfacerunoff characteristics (Euliss and Mushet 1996).

The increased sediment in the wetland has severalpotential impacts on the ability of the wetland tofunction at sustainable levels. These include

• decreased water storage volume,• decreased seed bank and propagule viability,

Table 12. Extent of palustrine wetlands in conterminousU.S. by selected broad land cover type (USDA,NRCS 2000b)

Land Cover Type Palustrine Wetland Extent(million ha)

Cropland 4.1

Pastureland 3.1

Rangeland 3.1

Forest land 26.3

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• decreased survivability of invertebrates andinvertebrate egg banks,

• buried organic substrates and microbes withinorganic soil, and

• shallower basins that can drastically alter plantcommunity composition and wetland type (Eulissand Mushet 1999; Gleason and Euliss 1998).

Changes in the physical characteristics of the prairiepotholes resulting from increased sediment mayadversely affect ecosystem processes such as primaryproductivity, trophic structure support, and nutrientcycling and transformation (Gleason and Euliss 1998).

The ultimate result is that both restored and naturalwetlands have a shortened existence on the landscapebecause of increased sediment deposition from tillage(Gleason and Euliss 1998). If past land use impactsare not considered in restoration design and imple-mentation of temporary and seasonal prairie potholewetland in the NPPR, then restoration of hydrologicfunctional capacity will be less than sustainable untilsuch modifications are addressed and remedial resto-ration action is taken.

The functional loss from complete sedimentation of arestored or natural prairie pothole is obvious, but theeffects on wetland functions from the gradual fillingin over time are not currently well documented(Gleason and Euliss 1998). The prairie pothole wet-land function, Retention of particulates, is intendedto capture the natural filtering ability of a temporaryor seasonal prairie wetland (Lee et al. 1997). Thevariables measured for the function are designed toreflect this natural filtering capacity at a sustainablefunctional condition. Any changes within the catch-ment or the wetland that would accelerate sedimentdeposition in the prairie pothole resulted in a low FCIvalue. The median FCI value of 0.75 was calculated atT1. This score indicates that, while most of the sitesscored at a relatively moderate level (site FCI valuesranged from a minimum of 0.67 to a maximum of0.88), historic land use practices have likely resultedin less-than-sustainable functional conditions follow-ing restoration. None of the restoration sites exhibiteda sustainable functional condition regardless of landcover (i.e., on CRP lands) or age.

Although the median FCI for the reference sites was0.81, 40 percent of the reference sites had an FCIvalue between 0.04 and 0.15. These low site FCI

values indicate that activities within the catchment orwetland have historically impaired or are currentlyimpairing the condition of the wetland to a degreethat they can no longer function at sustainable levelsto remove particulates from the surrounding landscape.

The results indicate that for sustainable conditions tobe achieved in wetlands targeted for restoration, tech-niques addressing past land use practices (e.g., estab-lishment of properly maintained water control struc-tures, removal of the deposited sediment) are impera-tively needed (Galatowitsch and van der Valk 1994).Otherwise, degraded functional conditions remain,regardless of the number of acres counted as restored.

Wetlands in the NPPR that are individually restoredwithin a catchment that is still primarily in agricul-tural production may continue to experience degrada-tion. Certainly restored wetlands that return to pro-duction because of short-term contracts associatedwith the CRP are at high risk to return to degradedconditions. This is particularly true of temporaryprairie pothole wetlands. Euliss and Mushet (1999)found lower diversity and number of aquatic inverte-brates in temporary wetlands embedded in catchmentbasins within intensively farmed agricultural fieldscompared to those located in grasslands of U.S. Fishand Wildlife Service Waterfowl Production Areas orsimilar grassland habitats in the Prairie Pothole Re-gion of North Dakota.

Temporary wetlands are considered the most vulner-able wetland type in the PPR, often cropped in all butthe wettest years. Such wetlands are routinely tilledand exposed to direct applications of fertilizers,pesticides and herbicides. Temporary wetlands arecritical to waterfowl as they are the first wetlands tothaw during the spring when physiological conditionsof newly arrived waterfowl are at their lowest. Al-though drought years have historically limited thenumber of wetlands available for waterfowl (Grue etal. 1989), the initiation of drainage associated withagriculture during the late 1800’s in the Prairie Pot-hole Region and the continued cropping of temporarywetlands can adversely limit the numbers of tempo-rary wetlands necessary to satisfy the high caloricrequirements of waterfowl during the early part of thebreeding season.

A median FCI value of 0.69 was calculated for therestoration at T1 for the Removal of imported ele-

21



ments and compounds function. Although this doesnot reflect a sustainable functional level, the valuenevertheless indicates that some degree of removal ofelements, including pesticides, is occurring in therestored wetlands sampled. A higher median FCI,0.80, was calculated for the reference sites. Much likethe sediment-filtering capacity addressed above, thevariables assessed for the elemental removal functionare intended to reflect a gradient of disturbanceactivities that can either support a sustainable func-tional capacity or impair it.

Like the retention of particulates, wetlands are oftenmanaged as depositories of undesirable elements,with the expected result that they will transform orbury any adverse element without functional impair-ment. However, input of these materials from thesurrounding landscape into wetlands (particularlywhen it is cropland), either in the water column orattached to sediments, can be potentially lethal towaterfowl and their food sources.

A 1987 study investigated the effects of aerial applica-tion of a pesticide, ethyl parathion, on mallard duck-lings. The pesticide was applied to sunflower fieldsimmediately adjacent to prairie pothole wetlands.Survival data on mallards that had broods and se-lected aquatic invertebrates was collected before andafter a routine application of the pesticide. Compa-rable data was also collected for five fenced controlwetlands embedded in dense nesting cover or nativegrassland. Survival was 32 to 65 percent of the duck-lings in the control wetlands compared to 3.8 percentfor the treated wetlands.

Brain cholinesterase (ChE) activity was severelydepressed in all but one of the ducklings in the treatedwetlands. Cholinesterase in brain and blood tissues isa reliable indicator of exposure to organophosphatepesticides and may be diagnostic of death resultingfrom exposure to such contaminants (Hill andFleming 1982). Invertebrates in the treated wetlandswere also negatively impacted. Amphipod survivalwas significantly reduced over a 25-day period follow-ing application (Grue et al. 1989).

In another study, Dieter et al. (1995) investigated thelethal and sublethal effects of phorate, an organo-phosphate pesticide, on mallard duckling survivabil-ity. Phorate is commonly used in fields and tilledwetland basins in the Prairie Pothole Region, and is

toxic to birds (Dieter et al. 1995). Phorate can befound concentrated in wetland sediments, in thewetland water column, or directly in agriculturalrunoff from fields. The study documented the acutelethal exposure of phorate to mallard ducklings aswell as the sublethal effects of inhibited brain andblood ChE in mallard ducklings that also results inaltered behavior and survival. In addition, phorate canbe lethal to invertebrates and absorbed by planttissues, both major food items of mallard ducklings(Dieter et al. 1995). Because phorate is representativeof many organophosphates used in the Prairie PotholeRegion, the continued use of such pesticides withinrestored and natural wetland basins and in surround-ing fields will likely continue to pose an adverse riskto mallard and other waterfowl young that use them.

The range of estimated site FCI values at T0 waslower for the Habitat structure within wetland

function compared to that for the Habitat intersper-

sion and connectivity among wetlands function forthe NPPR sites. The difference between the mean FCIvalues calculated for conditions following the onset ofrestoration for both functions (0.71 within-wetlandhabitat structure function vs. 0.78 for the spatiallyexplicit habitat function) does not appear to be sig-nificant. But the lower mean FCI value for within-wetland habitat structure, coupled with the lowerestimated site FCI range for this function, may indi-cate that restoring the conditions necessary to sup-port wildlife habitat within temporary and seasonalpothole wetlands is somewhat more difficult to achievebecause of past land use of these wetland types.

A breakdown of estimated and calculated FCI valuesby wetland type (temporary and seasonal) for therestoration sites indicates that there are relativelysmall differences in the mean FCI values betweenwetland types at T0 for the within-wetland habitat oramong-wetland interspersion and connectivity func-tions. The difference at T1 between the within-wet-land habitat mean FCI value and the spatial configura-tion function mean FCI value assessed for temporarywetlands is somewhat greater (table 13). The meanFCI at T1 for the within-wetland habitat function islower for temporary wetlands than the among-wet-land interspersion and connectivity function meanFCI for temporary wetlands.

In addition, the within-wetland habitat mean FCI at T1is lower for the temporary wetlands than for the

22



seasonal wetlands. These results again suggest thatpast agricultural activities within temporary wetlandsimpair the ability of restored temporary wetlands toachieve sustainable functional capacity over time. Theresults may further suggest that the variables used toassess conditions of within-wetland habitat structureare more sensitive to past land use within the wetlandor more easily capture its effects than the variablesused to assess the spatial configuration of the wetlandcomplex.

The variables included in the Habitat interspersion

and connectivity among wetlands function are in-tended to capture the importance of the prairie wet-land complex in the landscape, as well as the impor-tance of maintaining habitat structure and connectiv-ity of uplands surrounding wetland complexes. This isextremely critical for waterfowl, many of whichrequire wetland complexes connected by uplandgrasslands for nesting (Galatowitsch and van der Valk1994; Swanson and Duebbert 1989). Successful move-ment by hens and broods from the nest to wetlandbasins, to feed and escape upland predators, is depen-dent upon contiguous and dense upland herbaceouscover. The restoration of prairie pothole wetlands andthe surrounding uplands via the Conservation ReserveProgram may enhance the nesting success of water-fowl. In the NPPR of North Dakota and Minnesota,Kantrud (1993) evaluated the nest success of dabblingducks from 1989 to 1991 on CRP land compared tothat on U.S. Fish and Wildlife Service WaterfowlProduction Areas (WPA). Kantrud found that water-fowl nest success was 23.1 percent during this periodon CRP lands in areas of high wetland density com-pared to 8.2 percent on WPA lands of similar cover.

The data suggest that the higher nest success rate onCRP lands may have been related to enhanced protec-tion from predators, particularly for large dabblingduck species such as mallard and gadwall whosenests on CRP lands were located further from semi-permanent wetlands than on WPA sample sites. Inaddition to waterfowl, several studies have focusedon the value of CRP fields to grassland birds (Johnsonand Koford 1995; Johnson and Schwartz 1993) butspatial linkages between CRP upland and wetlandhave not been addressed.

Forested, low-gradient riverine wetlands, CMV

and LMAV

Changes in historic hydroperiods affect the ability ofrestored sites to reach a sustainable functioningcapacity. The less than sustainable functional capac-ity values calculated for the Temporary storage of

surface water function before and after restorationwas initiated on the forested, low-gradient riverinewetlands of the LMAV indicate that hydrologic modifi-cations outside the wetland under restoration are stillhampering sustainable functional capacity. Similarly,only 36 percent of the combined 30 restoration sitesfrom the LMAV and CMV exhibited sustainable func-tional capacity values for the Retention and retard-

ing ground water function. This indicates the impor-tance of the linkage between offsite hydrologic modi-fications and the ability to restore sustainable func-tional capacity.

Although none of the restoration sites sampled in theCMV and LMAV involved construction of water con-trol structures to restore wetland hydrology, thismanagement technique is commonly used to restoresurface water conditions to a wetland. However,construction of water control structures at restorationsites does not guarantee a return to sustainable hydro-logic conditions. Placement of a water control struc-ture can result in development of a wetland in theDepressional functional class, particularly if thestructure is accompanied by removing the wetlandsoil to deepen the wetland below the original surfacelevel. Also, management of the structure may notmimic naturally occurring hydroperiods. This canresult in less than sustainable hydrologic functioning.Management to mimic natural hydrologic variabilitycharacteristic of the subclass can often be difficult, ifnot impossible, because of land practices (levee andditch construction/maintenance) on and off site.

Table 13. Temporal and spatial comparison of meanfunctional capacity index values of habitatfunctions between temporary and seasonalprairie pothole restoration sites, NPPR

Within-wetland habitat Among-wetland intersper-sion and connectivity

Temporary Seasonal Temporary Seasonal

T0 0.17 0.12 0.33 0.28

T1 0.68 0.75 0.78 0.78

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Hydrologic restoration is undoubtedly one of the mostdifficult functions to achieve in the CMV and LMAVbecause of the extensive network of drainage chan-nels and levees. King and Allen (1996) suggest thatwhere watershed-wide hydrologic restoration is notfeasible, a complex of impoundments similar to green-tree reservoirs may restore forested riverine wetlandsdependent on periodic flooding. However, implemen-tation and management of such systems require along-term commitment to emulate natural hydrologicvariability, as well as routine monitoring to ensurethat the management is in fact restoring sustainablelevels of all riverine wetland functions (King andAllen 1996).

Playa wetlands, the High Plains

As a result of the ephemeral nature of wetland playasurface water, the complexities of state water rightsand public vs. private use of water in the High Plains,and the historic modifications of playas to support agri-cultural interests in the Plains, the continued existence ofplayas depends on their ability to provide sustainablefunctions that will accommodate a variety of societal uses.

The focus of most playa research has been on the useof playas for sources of irrigation water and feedlotwaste retention. Also considered is their importancein recharge of the Ogallala aquifer, primarily on theSouthern High Plains (SHP) (Scanlon et al. 1994;Wood and Sanford 1994; Lehman 1972). Effects offeedlot waste retention within playas have focused onpotential contamination effects on the Ogallala. Thealmost impermeable clays of playa bottoms, alongwith the further sealing from organic feedlot wastematerial, have shown playas to be potentially effectivelong-term traps of such material (Stewart et al. 1994).

Stewart et al. (1994) found that most nitrate wasremoved in three playas used for long-term feedlotwaste storage and treatment at a depth of 10 feet,with high accumulation occurring in the upper 1 footof the playa clay. There was greater leaching of nitrateinto the ground water above the playa clay where soilbecome coarser and more permeable. Presumably,nitrate is being denitrified within the saturated soil ofthe playa.

Haukos and Smith (1996) suggest, however, thatnutrient cycling and transformation processes arepoorly understood in playas and that further researchis warranted. In addition, a more robust data set is

needed to further determine the long-term viability ofplayas for animal feedlot waste storage and treatment(Stewart et al. 1994). Investigation of feedlot wasteretention effects on biological systems is also warranted.

Similar to the temporary and seasonal prairie pot-holes of the NPPR, playas in cultivated watersheds ofthe SHP have greater sediment deposition than doplayas in rangeland watersheds (Luo et al. 1997).Playas in cropland had 8.5 times more sedimentaccumulated than did those within rangeland water-sheds. In particular, cropland watersheds that havemedium-textured soil had significantly higher depthsof sediment accumulation in playas than did croplandwatersheds that have fine-textured soil, or rangelandwith either soil texture type (Luo et al. 1997). Increas-ing inputs of sediment into playa wetlands will even-tually obliterate their presence on the High Plainslandscape. In the interim, the wet phases of the playahydroperiod will become increasingly shorter. Theresult will be forms of increasingly intensive andexpensive restoration and management to maintainwetland functions, particularly to support criticaloverwintering, migratory and breeding habitat fornumerous species of waterfowl and shorebirds aswell as the sandhill crane, Grus canadensis (Andersonand Smith 1998; Smith 1994).

Croplands properly treated and maintained witheffective conservation practices, as well as thoseenrolled in the Conservation Reserve Program, ex-hibit decreased rates of sedimentation (Luo et al.1997). However, lack of effectively maintained orimplemented conservation practices and declines inamount of CRP land will ultimately reduce the func-tional longevity of playa wetlands on the High Plains.

Hydrogeomorphic method modelrefinement and validation

The hydrogeomophic method (HGM) approach towetland functional assessment was selected for use inthis effort for several reasons. The approach providesa recognized method of assessing wetland functionalcapacity (Smith et al. 1995). The method employed inHGM focuses on the functional capacity of wetlandsand not on their societal values, thereby allowing amore scientific approach to wetland functional as-sessment (Brinson 1996). As stated earlier, the assess-ment provides a numerical score of the functional

24



capacity for each function assessed in a wetland,thereby avoiding ambiguity involved in ratings ofHigh, Moderate, and Low. In addition, NRCS hasalready invested in the development of interim HGMmodels as required in Swampbuster to evaluatewhether agricultural impacts to wetlands are minimaland the ratio of compensatory mitigation required tooffset impacts. And, most importantly, the methodwas selected because the approach directs the devel-opment of functional variables to include not onlythose within the wetland itself but also the character-istics of the landscape that can affect the relativefunctional condition of a wetland (Smith et al. 1995).

The models used to assess prairie pothole wetlandsare assembled in a draft regional guidebook (Lee et al.1997). An interagency team identified reference wet-lands and collected data from them to develop theindex used to score functional capacity for eachfunction assessed. As discussed above, the landscapesurrounding the prairie wetlands and the past andpresent land uses of the landscape exert a profoundeffect on the functional capacity of temporary andseasonal prairie pothole wetlands in the NPPR. How-ever, validation of the models has not been completedto date although efforts to do so are underway (NedEuliss, personal communication). Validation of themodels could result in changes in the FCI valuesreported, as well as a change in the number of vari-ables measured or the scoring of any variable for anygiven function.

Much like the prairie potholes to the north, the playawetlands of the High Plains are embedded in a land-scape dominated by agriculture. Playas have histori-cally been used as sources for livestock watering and,as the only source of surface water, for irrigationwater. The scientific knowledge of playas, however, ismuch less well known than their uses.

The HGM models used to assess the playa wetlandsare adaptations of the prairie pothole models, butwere developed without reference wetlands data,much like the models for the forested, low-gradientriverine wetlands. However, the forested wetlands ofthe LMAV have been studied for a longer time thanthe playa wetlands of the High Plains; hence there is abetter understanding of their ecology and the poten-tial effects from disturbances and alterations.

The playa HGM models were developed with theinformation available at the time. In addition, themodels were developed to evaluate minimal effects toplaya wetlands from agricultural activities perSwampbuster. Establishment of reference wetlandsfor the High Plains playa wetland subclass and theforested, low-gradient riverine wetland subclass in theCMV and LMAV would improve model outputs.

In addition, inclusion of functional variables thatreflect different development stages (based on vegeta-tion structure and/or other physical features) withinthe reference data set for both wetland subclasseswould provide a finer-tuned index of functional ca-pacity for each. Although lacking the benefit of refer-ence data, the results generated from application ofthe interim HGM models still provide a documentedmeasure of change in wetland functional condition forplaya wetlands of the High Plains and forested, low-gradient riverine wetlands of the CMV and LMAV.

25



Recommendations

The results of the National Wetlands FunctionalAssessment Pilot indicate that several methods areavailable for NRCS to monitor change in wetlandfunctional condition. However, factors such as scaleof assessment, the cumulative effects of anthropo-genic alterations on the functional condition of wet-lands within a landscape, and the ability to captureand accurately report agency performance in wet-lands restoration and management argue for a multi-faceted approach to assess wetland functionalchange. Furthermore, the results suggest that NRCSshould take additional steps that would assist fieldstaff in attaining the highest functional conditionpossible on wetland restoration sites.

The first three recommendations address methods toassess and monitor change in wetland functionalcondition. The methods are listed individually, aseach provides different types of information relativeto wetland functional condition. Together, they pro-vide a comprehensive assessment approach. Periodicevaluation of the methods is needed to determinetheir relevance to the NRCS mission and strategicplan goals. The last three recommendations focus onactivities that would enhance wetland restorationactivities at the field level. These recommendationswould also better integrate the application of restora-tion activities in the field with assessing change inwetland functional condition at a national level.

1. Broad-scale assessment

The Resource Assessment Division (RAD), Soil Sur-vey and Resource Assessment Deputy Area, shouldcontinue to develop and routinely assess broad-scaleindicators of potential degradation to wetland ecosys-tem functioning, using GIS, remote sensing data, andmodeling. Although the assessments could focus on aspecific HGM subclass throughout a landscape, thepurpose of such assessments would be to addressdegradation processes potentially affecting all wet-lands on a landscape regardless of subclass (HUC-8,MLRA’s, Bailey’s Ecoregions). For example, researchunderway in the NPPR (USGS, Northern PrairieWildlife Research Center) is seeking to identify mul-tiple-scale indicators of wetland condition. Using

these preliminary results, NRCS could begin to peri-odically assess several of these indicators, or othersnot yet identified through current research efforts.For temporary and seasonal prairie pothole wetlands,NRCS could potentially monitor the following threeindicators of change resulting from landscape degra-dation processes identified by this research:

• net loss of and ratio of temporary wetlands onthe landscape

• potential change in basin inorganic sedimentlevels

• shifts in vegetation zonal patterns

The ability to determine a reference condition foreach of these will require coordination with theNorthern Prairie Wildlife Research Center (USGS,BRD); Environmental Protection Agency, EMAP;Wetlands Science Institute, NRCS State Offices in theNPPR; and others involved in research affectingtemporary and seasonal wetlands in the NPPR.

In lieu of a site-specific FCI derived from the HGMmodels, absolute measurements would be derived andtracked. Several methods will be required. For ex-ample, a net loss of temporary wetlands could bederived from new data elements added to the NRI or ageospatial wetland data set. Estimated number oftemporary wetlands and the ratio of temporary:seasonal and temporary:semipermanent could bederived, based on historic published records or viaconstruction of potential historic distribution (seebelow).

Potential changes in wetland inorganic sedimentlevels could be derived from modeling sediment yieldfrom uplands into the basins under different croppingor grazing practices and crop or vegetation covers. Abaseline level could be determined to calibrate themodel from in situ sediment deposition in selectedbasins. Initial work by Kantrud and Newton (1996)indicates that several potential wetland vegetationindicators are linked to agricultural activities; ex-amples are changes in zonation patterns and extent ofunvegetated wetland surface. With appropriateground-truthing to calibrate baseline conditions andremote sensing data, such indicators could provideanother measure of the extent to which degradationprocesses affect functioning of wetland ecosystems.

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2. Site-specific assessment

The broad-scale approach described above provides ameans of monitoring potential degradation to wetlandfunctioning. However, it does not provide a means toassess changes in wetland functional condition at afiner scale and for specific subclasses. This could bedone for selected geographic regions periodically,using a site-specific approach, such as the HGMmethod. Periodically assessing wetland condition at asite-specific scale provides a mechanism to evaluatelocal perturbations to wetland ecosystem functioningthat could not be easily detected or are not evident ata broad scale. Local-scale monitoring would alsoprovide a numerical basis for tracking functionalcondition for specific functions through the continueduse of the HGM method.

Although the Wetland Restoration training sponsoredby NRCS does include monitoring of wetland functionat a site-specific level, results from application of thistraining are not required to be reported. Evaluationand required reporting of functional condition at thisscale could be entered into the NRCS Performance

and Results Measurement System for specific sub-classes, although some refinement of the reportingsystem is needed to accommodate such data. Asubsample of wetland restoration sites funded byUSDA programs and reference wetlands benefitingfrom other conservation practices would provide amore complete picture of NRCS wetland managementactivities than is currently available.

To initiate this level of assessment, an interdiscipli-nary workgroup of approximately 8 to 12 individualsshould be established within NRCS, led by the Wet-land Science Institute. The workgroup would coordi-nate and establish wetland reference data sets for theforested, low-gradient riverine wetlands of the CMVand LMAV and playa wetlands of the High Plains. Thefeasibility of including other wetland subclasses (e.g.,Delmarva wet hardwood flats, slope wetlands of thewestern United States, salt marshes of the New En-gland Coastal Plain) should also be explored.

The workgroup should focus on refining existingNRCS interim HGM models for only those functionsthat could be assessed over time using primarilyremote sensing (satellite imagery, high-resolutionaerial photography) and limited field data collection

(although field collection will dominate initially toestablish the reference data set to develop appropri-ate index scores). The workgroup should coordinatewith other agencies and institutions to build uponongoing studies and Agency expertise.

Although the HGM assessment procedure ultimatelycan provide a relatively useful assessment tool, thereare critical limitations associated with current proto-col to build the functional capacity index models.Often there is little, if any, information regardinghydrologic or biogeochemical processes, and theinteragency team members must either rely on ge-neric literature or use best professional judgement.Much energy is devoted to development of variablesand models for these functions, yet the reality is thatthe models often represent what is believed to beoccurring, not what is documented. To remedy thisoften tedious and costly approach, variable selectionand measurement should be at as generic a scale asthe interagency team feels comfortable, until suchtime that documentation allows refinement. In thisregard, it is suggested that as reference data is col-lected, gaps in knowledge should be identified andappropriate steps be taken to work with the researchcommunity to cost-effectively address those gaps.

Once the reference wetlands are established andselected functional models developed and calibratedfor the chosen subclasses, a statistically derivedsubsample of restoration and reference sites shouldbe selected for assessment. FCI values for the se-lected functions assessed could then be reported.Periodic assessment of the wetlands could occur at afrequency tailored to the age of the wetland (forrestoration sites), wetland subclass, and the functions tobe assessed.

3. National resources inventory wetland data

elements

The NRI provides a means of collecting data across aspectrum of wetland types (vs. HGM subclass). Infor-mation on data elements, collected from one NRI tothe next, is used to derive status and trends data. Forwetlands this has been primarily limited to acreagechanges. However, authorizing legislation for the NRIincludes statements about the quantity and quality ofhabitat for wildlife and fish, yet the NRI captures little

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about habitat quality, particularly with regard towetlands. The following wetland elements are recom-mended to be added to future NRI efforts:

• Soil data for wetland sites to document the spe-cific hydric criteria that are expressed at eachsample point. This will greatly assist in moreaccurately identifying what is or is not a wetlandfor both acreage and functional assessment pur-poses.

• Quantitative measures of soil erosion or sedimentdelivery to wetland sites that occur in agriculturalsettings (both from USLE, and perhaps by mea-suring the sediment depth on subsamples).

• Vegetative transect data for subsamples of repre-sentative wetland sites (such as has occasionallybeen done under Swampbuster).

• Extant factors such as grazing, pesticide runoff,traffic, and dumping, which apparently degradewetland quality or impede the achievement offunctional potential.

4. Wetland functional subclass identification

Identification of functional subclasses is needed toassist field staff in determining the appropriate type ofwetland for restoration based on geomorphic setting,hydrodynamics, and hydrologic source(s). Suchguidance would provide several beneficial resultsincluding the ability for NRCS to reliably link its on-the-ground wetland restoration activities and nationalefforts to identify and track changes in wetland condi-tion. Just as importantly, such a mechanism wouldenable NRCS and its partners to implement appropri-ate restoration techniques for specific wetland sub-classes. This would improve the treatment effects ofwetlands on the landscape, particularly when com-bined with other land treatment practices.

Although issues such as concerns of adjacent land-owners and specific enhancement features desired bya landowner are also valid factors in designing resto-ration projects, understanding and identifyinghydrogeomorphic features of a wetland subclassprovide a sound basis for other proposed modifica-tions. Such guidance should be incorporated intoNational Conservation Practice No. 657, WetlandRestoration. The Science and Technology and Re-source Assessment and Soil Survey Deputy Areas andthe Wetland Science Institute should coordinate thiseffort.

5. Geospatial wetland restoration strategy

In conjunction with identifying wetland subclasses, amore comprehensive restoration approach is alsorecommended. This is based on work underway in theNRCS New Hampshire State Office (Ammann 1999).The results from this pilot, as well as the currentscientific literature, indicate that the ecological condi-tion of the landscape in which wetlands are imbeddedaffects the functional condition of wetland ecosys-tems. If wetland restoration is to achieve highestsustainable conditions, part of the solution is torestore and protect as many of the historic nativesystems as possible, including wetlands, and do it sothat functioning ecosystems emerge on the landscape.

In addition, information on the historic and currentlandscape and the stressors influencing wetlandecosystem functioning provide a way of determiningwhere restoration activities are most needed andlikely to succeed. The core of the ecosystem restora-tion process developed by Alan Ammann, PhD., inNew Hampshire uses a Geographic Information Sys-tem and existing data to

• identify the extent and type of native ecosystemshistorically present,

• identify the anthropogenic stressors that havealtered that environment, and

• identify land ownership as well as protectedareas.

The GIS products allow NRCS and its partners anefficient way to integrate many different data sets anddevelop a management/restoration strategy for thearea. Potential management/restoration sites are theninventoried. Management and restoration techniquesspecific to the ecosystem targeted are then imple-mented. The sites are monitored to ensure that theactivities implemented are successful, and identifyany additional management that may be needed. Theapproach provides a sound basis for ecosystem resto-ration within a landscape context, and can also beused to help refine wetland subclass identification.

6. Ecological site descriptions

Ecological sites are the interpretive units for range-land and forest land. Many wetlands exist on theseland types and are managed for livestock production.Ecological sites provide a way to inventory, evaluate

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and manage range and forest lands. The informationdeveloped for ecological site descriptions – soils,hydrology, plant community composition and dynam-ics, disturbance events, anthropogenic alterations,and management interpretations – is similar to thatdeveloped for HGM wetland subclass profiles, al-though use of the information differs between thetwo. Ecological sites are described based on physicalfactors, particularly soils, that characterize a specificplant community and the amount of vegetation pro-duced by that community. Because they are institu-tionalized within NRCS, development of ecologicalsite descriptions for wetlands on range and forestlands would enhance the understanding of ecologicalsite dynamics within a subclass and provide manage-ment scenarios resulting from different site character-istics. This information would be useful in designingand managing wetland restoration sites.

For wetlands that are not on rangelands or forestlands, as defined within the NRCS “National Rangeand Pasture Handbook” 190-VI, similar information iswarranted and could be provided in a handbookformat for field use. The Science and Technology andResource Assessment and Soil Survey Deputy Areasand the Wetland Science Institute should initiatecollaboration on both efforts.

Summary

Between 1992 and 1996, $274,000,000 was appropri-ated to the Natural Resources Conservation Servicefor the Wetland Reserve Program to restore some ofthe 1.7 million acres historically lost through agricul-tural activities in the Mississippi River drainage andother regions in the conterminous United States. As ofFebruary 2000 during the 20th signup for the USDAConservation Reserve Program, approximately 63,199hecartes of cropped wetland were accepted into theprogram (USDA, FSA 2000). Program contracts areaccepted for a 10- to 15-year period, removing andconserving land unsuitable for agriculture and return-ing, if not all in perpetuity, some portion of it to nativeor managed grassland and, where feasible, prairiewetland. The PPR in North Dakota, South Dakota andIowa comprise slightly more than 54% of the totalcropped wetland acreage accepted for restoration inthe 20th CRP signup (USDA, FSA 2000).

The continued decline of wetland losses—31,995hectares per year during 1982–92 vs. 105,300 hectaresper year from the mid-1970’s to mid-1980’s (Flather etal. 1999)—and the large acreage numbers acceptedinto USDA wetland restoration programs (269,325hectares accepted into the Wetlands Reserve Programfor restoration between 1992 and 1999; Flather et al.1999) are often provided as the barometer of wetlandecosystem recovery. Continuing to focus only onwetland acreage, however, does not adequately ad-dress the functional capacity of or degree of impair-ment to wetland ecosystems. Applying comprehensiveand integrated conservation treatments upon thelandscape, including wetland restoration, argues forthe need to document and quantify change in wetlandfunctional condition.

Although the HGM wetland functional approachprovides a standard method with which to monitorchanges in functional capacity, a greater degree ofconfidence and precision in FCI values can be ac-quired through development of wetland referencedata sets. Calibration of the playa and forested, low-gradient riverine wetland interim functional modelsthat have reference wetland data would help to de-velop standards for assessing selected functions inthese wetlands for continuing national assessment

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purposes. In addition, it is important to capture thestressors operating at multiple spatial scales withinlandscapes to assist in targeting functionally sustain-able restoration sites. Identifying the stressors and therelative degree of degradation in a landscape willallow the development of appropriate surveys ormonitoring efforts to gauge changes in wetland func-tional condition and proactively identify policy, pro-gram, and funding factors necessary to maintainsustainable wetland ecosystems.

The NRCS has shown a relative increase in wetlandfunctional capacity index values on agricultural landstargeted for restoration within the temporary andseasonal prairie pothole wetland subclass of theNorthern Prairie Pothole Region; the forested, low-gradient riverine wetland subclass of the Central andLower Mississippi Valley; and the playa wetlandsubclass of the High Plains. The results also indicatethat the current landscapes in which restorations areoccurring do not reflect historic conditions and, as aresult, a return to functional sustainability isthwarted. The results, however, provide a context inwhich NRCS can develop a refined, proactive ap-proach to identify and quantify changes in wetlandfunctional condition on private lands in the 21st century.

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Wood, W. W. and W. E. Sanford. 1994. Recharge to theOgallala: 60 years after C. V. Theis’s analysis. InProceedings of the Playa Basin Symposium(Urban, L. V. and A. W. Wyatt, co-chairs), pp. 23–34. Texas Tech University Libraries Playa/Ogallala Aquifer www.lib.ttu.edu/playa/text94/toc.htm.

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Appendix ADescription of Study Area

Northern Prairie Pothole Region

The Northern Prairie Region (NPR) includes thePrairie Pothole Region (PPR), which extends fromsouth-central Canada into the north-central UnitedStates and the Nebraska Sandhills (Lee et al. 1997).The U.S. portion of the PPR extends along the north-ern boundary of Montana, into northern and easternNorth and South Dakota, western Minnesota, andsouth into the Des Moines lobe of north-central Iowa(Lee et al. 1997). The PPR can be further divided intothe northern and southern PPR. The northern PPR(NPPR) is characterized by a cooler and less humidclimate than the southern PPR and is dominated bysmall grain crops. The southern PPR has a higheramount of precipitation than the NPPR and is domi-nated by such row crops as soybeans and corn (Lee etal. 1997). Mixed- and tall-grass prairie are the potentialnatural vegetation of the PPR (USDA, NRCS 1981).The Nebraska Sandhills is a 52,000 square kilometersstabilized dune field dominated by irrigated agricultureand cattle ranching (Mitsch and Gosselink 1993). Thestudy area is confined only to the NPPR (fig. 1).

The NPR is characterized by inter- and intra-annualfluctuations in seasonal mean temperature, humidityand precipitation. Periodic droughts are commonbecause of variability in the regional climate. Precipi-tation measures than 11 inches of precipitation fromApril through September every 2 out of 10 years (Leeet al. 1997). The climatic variability of the NPR domi-nates hydrodynamics of the region, affecting all wet-land functions.

Millions of prairie potholes dotted the glacial land-scape of the PPR historically. Before the Europeansettlement the area covered an estimated 80,000square kilometers (Frayer et al. 1983). Conversion ofthe prairie landscape to agriculture eliminated many ofthese potholes, particularly those that dried in mostyears and could be tilled. An estimated 65 percent ofthe original wetland area in the PPR has been drained(Euliss and Mushet 1996). Much of the native prairiewas also put to the plow, with only scattered remnantsremaining by the beginning of the 20th century.

Several different hydrogeomorphic subclasses ofprairie pothole wetlands exist in the NPPR, all of themwithin the Depressional class (Brinson 1993). Ad-dressed in this study are temporary and seasonalwetlands (Stewart and Kantrud 1971). Temporary

wetlands are dominated by wet-meadow vegetation.Seasonal wetlands have a center zone of shallowmarsh surrounded by a zone of wet-meadow vegeta-tion. However, fluctuating water levels as well as landuse result in frequently alternating phases of thevegetation zones (Stewart and Kantrud 1971). Thewetlands are hydrologically dominated by surfacerunoff from snowmelt and spring rains, with hydro-logic losses due to evapotranspiration and groundwater recharge (Lee et al. 1997). They are found onhummocky and undulating collapsed topography ofthe glaciated NPR, typically with nonintegrated drain-age. Because of the closed basin topography and asignificant source of wetland hydrology originatingfrom the surrounding landscape, this wetland subclassis closely tied to the condition of the surroundinglandscape (Lee et al. 1997).

Central and LowerMississippi Valley

This portion of the study area is within two physi-ographic provinces, the Central Lowland Province andthe Coastal Plain Province (Fenneman 1938). TheCentral Lowland Province includes the Dissected TillPlains Section. The Dissected Till Plains Section existsas the exposed Kansan glacial drift, a nearly flat tillplain covered in loess that increases in depth close tothe large rivers. The Kansan ice sheet is consideredolder than the Wisconsin, and therefore the landscapeis more dissected than the adjacent Till Plains Sectioneast of the Mississippi River.

The origin of the loess in the Dissected Till PlainsSection is a result of glaciation. The loess was carriedby water onto floodplains and then distributed overthe till plain by wind. Bedrock immediately below theplain near the Mississippi River is comprised primarilyof Mississippian age resistant limestones.

Paleozoic age sandstone and shale underlie the lime-stones, but are rarely exposed except in narrow areasnear the Mississippi and Missouri Rivers (Fenneman1938). The study area encompasses those portions ofMissouri that drain into the Missouri and MississippiRiver within the Dissected Till Plains Section; they willbe referred to in this document as the Central Missis-sippi Valley (CMV). It is located above the confluenceof the Ohio and Mississippi Rivers (fig. 1). Below theMississippi-Ohio confluence lies the Mississippi Allu-

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vial Plain Section within the Coastal Plain Province(Fenneman 1931). This area will be referred to as theLower Mississippi Alluvial Valley (LMAV). The LMAVextends to the Gulf of Mexico, nearly 1,000 kilometersin length (Keeland et al. 1995) (fig. 1). The CMV andLMAV sample sites are respectively located in theBroadleaf Forest (Continental) Ecoregion Province,Central Till Plains, Oak-Hickory Section, and theRiverine Forest Ecoregion Province, Mississippi Allu-vial Basin Section (Bailey 1997; McNab and Avers 1996).

Bottomland hardwood (BLH) wetlands have histori-cally characterized the broad floodplains of these twophysiographic regions. They represent the most dra-matic wetland loss nationally (Keeland et al. 1995;Frayer 1991; Abernathy and Turner 1987; Hefner andBrown 1985). Historical acreage estimates put theextent of BLH wetland at approximately 10 millionhectares (Roelle et al. 1990), with an estimated 8million hectares accounted for in Arkansas, Louisiana,and Mississippi (Keeland et al. 1995). By 1937, approxi-mately half of the BLH wetlands had been lost (Tiner1984). An estimated less than 2 million hectarescurrently remain in the LMAV (The Nature Conser-vancy 1992).

Bottomland hardwoods are located along low-gradientwaterways and, where flood waters are not excludedby levees, are often flooded on an annual basis. Wherelevees or drainage canals have been constructed, thefrequency of flooding can be reduced considerably andeven eliminated, drastically altering ecosystem andlandscape functions. Bottomland hardwood wetlandsare classified as forested, low-gradient riverine wet-lands based on their geomorphic characteristics andhydrologic dynamics (Ainslie et al. 1999; Brinson 1993).

Bottomland hardwood wetlands found on the exten-sive floodplain of the mainstem Mississippi, as well ason the floodplains of the Missouri, Tensas, and othermajor tributaries in the Mississippi River basin, extendlaterally across a topographic, edaphic, and hydrologicgradient. These areas are often referred to as zones fordescriptive purposes and, in addition to characteristicvegetation, exhibit changes in redox potential, organicmatter decomposition, and fish and wildlife use(Mitsch and Gosselink 1993; Wharton et al. 1982).However, the zones are tightly coupled because of theflow of energy in the form of water, sediment, nutri-ents, and organisms that maintain the bottomlandhardwood wetlands. The zones characterized bytemporarily and seasonally flooded wetlands (Zones IVand V, Wharton et al. 1982) occupy the somewhathigher topographic positions of these major floodplains.

Low-order tributaries of the Mississippi are also oftendominated by temporarily- and seasonally-flooded

bottomland hardwood wetlands. These are forested,low-gradient, temporarily, and seasonally floodedriverine wetlands. They are characterized typically bya mixed-deciduous hardwood canopy, often domi-nated by oak species (Quercus spp.) as well as maple(Acer spp.), ash (Fraxinus spp.), American elm(Ulmus americana), sweetgum (Liquidambar

styraciflua), black gum (Nyssa sylvatica), and cotton-wood (Populus deltoides), particularly in the northernportion of the LMAV (Mitsch and Gosselink 1993).

The forested, low-gradient riverine temporarily andseasonally flooded wetlands in the CMV and LMAVwere selected for functional assessment. These wet-lands are located in Major Land Resource Areas(MLRA) 131, the Southern Mississippi Valley Alluviumand 115, the Central Mississippi Valley Wooded Slopes(USDA, NRCS 1999). Extensive agricultural land inthis region is planted to feed grains and hay for live-stock in the CMV and soybeans, rice, cotton, wheat,and sugar cane constitute the primary crops in theLMAV. Combined, MLRA 131 and 115 are approxi-mately 154,460 square kilometers in extent (USDA,SCS 1981).

The High Plains

The High Plains (HP) is a 5-million-year-old remnantlandform of the Great Plains that resulted from re-gional uplift and subsequent erosion of the surround-ing plains landscape (Trimble 1980). The landformextends from the southern edge of South Dakota souththrough two-thirds of Nebraska, clipping the south-eastern corner of Wyoming, continuing through west-ern Kansas, the eastern fringe of Colorado and NewMexico, and passing through the Oklahoma borderinto the Texas panhandle before ending at theEdwards Plateau (fig. 1). The High Plains is the centralportion of the Great Plains and extends for more than750 miles north to south (Trimble 1980).

The Southern High Plains (SHP), often referred to asthe Llano Estacado, occupy an area approximately82,000 square kilometers in extent (Bolen et al. 1989).The area is semiarid in the north and west and warm-temperate in the east and south (Bolen et al. 1989).Located south of the Canadian River in Texas and NewMexico, the SHP is characterized by intensive agricul-tural land use. Palacois (1981) estimated that 20,000square kilometers of the SHP supported irrigatedagriculture. The area lacks permanent surface watersbut was historically peppered with playa wetlands,although no historical figure of their extent is avail-able. The majority of the SHP lies within Major LandResource Area 77, comprising approximately 127,000square kilometers in size. Much of the SHP is in culti-

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vation for wheat and grain sorghum, and has corn,soybeans, alfalfa and vegetable crops grown underirrigated conditions (USDA, SCS 1981).

Somewhat more numerous, but still fewer in numberthan in the Southern High Plains, playa wetlandsextend through the Central High Plains generally northof the Canadian River to just north of the ArkansasRiver in Kansas and Colorado (Trimble 1980). A largeproportion of the Northern High Plains is covered insand dunes and loess, and the few playas that are inthis region are confined to the eastern boundary of theHigh Plains north of the Arkansas River to the SouthFork of the Republican River, Nebraska. A significantportion of Major Land Resource Area 72 comprises theCentral and Northern High Plains, an area covering77,220 square kilometers in size (USDA, NRCS 1981).This area is characterized by extensive fields of winterwheat, small grains, alfalfa, grain sorghum, and otherhay crops. The High Plains aquifer provides irrigationwater to grow sugar beets, corn, and grain sorghum(USDA, NRCS 1981).

Playa wetlands are hydrogeomorphically classified asDepressional (Brinson 1993). They are shallow, largelycircular basins that have surface water present be-cause of annual and seasonal precipitation events.High evapotranspiration, percolation, and regionallylocalized irrigation withdrawals account for hydro-logic outputs (Haukos and Smith 1993). Annual spe-cies dominate the seed banks of playas, and successfulspecies germinate and grow rapidly during relativelyshort and unpredictable precipitation events. This islikely the result of the highly variable fluctuatinghydrologic regime present, that is, several submerged-drawdown cycles in a single growing season. In addi-tion, vegetation structure can vary between playasbecause of the localized nature of the hydrologicinputs and losses (Haukos and Smith 1993). Basinsurfaces are composed of clays (primarily the Randallsoil) that form an almost impermeable layer betweenthe basin floor and the underlying Ogallala Formation.

The Ogallala is the principal geologic unit of the HighPlains and underlies approximately 80 percent of itsextent (U.S. Geological Survey 1999). In recent yearsstudies have identified the potential importance ofplaya wetlands to the recharge of the High Plainsaquifer, particularly where they overlie the OgallalaFormation (Wood and Sanford 1994). Significantlowering of this regional ground water source forirrigated farming occurred after World War II (1945).By 1977, more than 70,000 wells tapped into the Ogal-lala (Bolen et al. 1989). The water table of the Ogallaladecreased more than 15 meters between 1930 and 1980(Weeks 1986, in Bolen et al. 1989). By 1990, an estimated95 percent of water withdrawn from the High Plainsaquifer was for irrigation (McGuire and Sharpe 1997).

Playa basins formed in loess, primarily from the Qua-ternary Blackwater Draw Formation (Holliday 1989).There are several mechanisms currently believed to beresponsible for their formation, including deflationbecause of wind, fluvial erosion, and lacustrine deposi-tion, salt dissolution, and resultant subsidence, disso-lution of calcic soils and calcretes, and wildlife activi-ties, particularly American bison (Bison bison)(Gustavson et al. 1994). While playa is Spanish for“beach,” the Llano Estacado (meaning “staked plain”)may be a corruption of llano estancado meaning “plainof many ponds” (Bolen et al. 1989). In 1541 the Spanishexplorer Francisco Vasquez de Coronado first recordedthe presence of “some ponds, round like plates . . .”(Bolen et al. 1989). Dendrochronological data indicatethat his observations were made during an extremelysevere drought that lasted for approximately 25 years(Weakley 1943).

Because of the lack of permanent surface water, playabasins provide the major source of surface water.Most playas and their watersheds are closed systems,lacking a surface water connection between them(Bolen et al. 1989). Playa wetlands are dominated byprecipitation and runoff falling within the watershed.Evapotranspiration and seepage via cracks in themontmorillonitic clay into the Ogallala representhydrologic losses from playa wetlands. Infiltration intoadjacent permeable soil may also occur once the watertable within the playa rises above the relatively imper-meable clay soil lining the wetland surface (Wood andOsterkamp 1984).

The timing and duration of surface water varies,depending on the degree and type of alteration as wellas on local weather patterns. Unaltered playas typi-cally have surface water present from mid-springthrough midwinter (Ward and Huddleston 1972).Irrigated playas, however, are flooded during the latewinter and early spring (Guthery et al. 1982).

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Appendix BHGM Functional Models and Variables

Temporary and Seasonal Prairie Pothole Wetlands, NPPRForested, Low-Gradient Riverine Wetlands, CMV and LMAV

Playa Wetlands, the High Plains

Functional Capacity Index Models

Subclass Function Model

Temporary and Static surface (VOUT x ((VSOURCE + VUPUSE +VSUBOUT)/3 + (VWETUSE + VSED + VPORE)/3)/2)1/2

seasonal water storage Prairie Pot- hole wetlands, NPPR

Dynamic surface If VPIT is 1.0, then VPIT is not used in the FCI calculation: water storage (VOUT + (VSOURCE + VUPUSE)/2 + (VPORE + VWETUSE)/2)/3

If VOUT is < 0.5, or VPIT is < 0.75, then FCI is 0.0. Otherwise, use:[(VPIT + VOUT)/2 + (VSOURCE + VUPUSE)/2 + (VPORE + VWETUSE)/2]/3

Nutrient cycling ((VUPUSE + VWETUSE + VSED)/3 + (VPCOVER + VDETRITUS)/2 + (VSOM + VPORE)/2)/3

Removal of [((VSOURCE + VOUT + VSUBOUT + VPIT)/4) x ((VUPUSE + VSED)/2 + (VPCOVER + VWETUSE + VDETRITUS)/3

imported + (VSOM + VPORE)/2 + (VBDENSITY + VVCONTINUITY + VBWIDTH)/3)/4]1/2

elements and compounds

Retention of If VOUT < 0.5, use: particulates [(VUPUSE + VWETUSE + VSED + VOUT)/4 + (VBDENSITY + VBCONTINUITY + VBWIDTH)/3]/2

If VOUT > 0.05, use: [(VUPUSE + VSED)/2 + (VBDENSITY + VBCONTINUITY + VBWIDTH)/3]/2

Provide (VWETUSE + VSED +VOUT + VPIT + VSUBOUT + VPRATIO + VPCOVER + VDETRITUS + VSOM)/9

environment for characteristic plant community

Wetland habitat (VUPUSE + VWETUSE + VSED + (VPRATIO + VPCOVER)/2 + VDETRITUS + VOUT + structure (VBWIDTH + VBCONTINUITY + VBCONDITION)/3)/7

Habitat inter- [((VUPUSE + VWETUSE + VOUT)/3 x ((VWDEN + VWAREA + VWPROXIMITY)/3)]1/2

spersion and Until reference standards are available for VWPROXIMITY, use: connectivity [((VUPUSE + VWETUSE + VOUT)/3 x ((VWDEN + VWAREA)/2)]1/2

Forested, low- Temporary [(VFREQ x VXSEC)1/2 x (VROUGH + VSLOPE)/2] gradient riverine storage of wetlands, CMV, surface LMAV water

Retention and (VWTGRAD x VCONDUC)1/2

retarding the movement of ground water

Cycling of [VBTREE + VSHRUB + VHERB/3) + (VWD + VDETRITUS)/2]/2

nutrients

Removal and se- [(VFREQ x (VSORPT + VREDOX + VDETRITUS + VWD)/4]1/2

questration of elements and compounds

Retention of [(VFREQ x VXSEC)1/2 x (VROUGH + VSLOPE)/2]1/2

particulates

B-2

Manure Nutrients Relative to the Capacity of Cropland and Pastureland to Assimilate Nutrients:

Spatial and Temporal Trends for the United States


Functional Capacity Index Models—Continued

Subclass Function Model

Organic carbon [(VLITTER + VWD)/2 x (VFREQ x VSURFCON)1/2]1/2

export

Provide environ- [(VCOMP + (VDTREE + VBTREE)/2)/2 x (VFREQ + VPOND + VWTD + VSOIL)/4]1/2

ment for native plant community

Provide wildlife [(VFREQ + VPOND + VMACRO)/3) x (VCOMP + VBTREE + VDTREE + VLOG + VLITTER + VSNAGS)/6] x habitat (VSIZE + VCONNECT + VCORE)/3]1/3

Playa wetlands, Maintains char- (VMOD + VSED + VSOADD + VSORED + VUPUSE + VWETUSE)/6

High Plains acteristic hydrologic regime

Maintains ele- [((VBUFFCON + VBUFFWID)/2) + VMOD + VPDEN + VPORE + VSED + VWETUSE]/6

mental cycling

Retains [((VSED + VUPUSE)/2) x VMOD]1/2

particulates

Maintains char- (VCANOPY + VMICRO + VMOD + VPDEN + VPRATIO + VSED + VWETUSE)/7

acteristic plan community

Maintain habitat [((VBUFFCON + VBUFFWID)/2 + VCANOPY + VPDEN + VPRATIO + ((VSED + VUPUSE + VWETUSE)/3)]/5

structure within wetland

Maintain food [((VBUFFCON + VBUFFWID)/2 + VDETRITUS + VLANDSP + VPRATIO + VSED + VUPUSE + VWETUSE]/7

web

Maintains habi- [[((VBUFFCON + VBUFFWID)/2) + VCANOPY + VPDEN + VPRATIO + ((VSED + VUPUSE + VWETUSE)/3)]/5 + tat interspersion VLANDSP + VWDEN]/3

and connectivity among wetlands

B–3

Manure Nutrients Relative to the Capacity of Cropland and Pastureland to Assimilate Nutrients:

Spatial and Temporal Trends for the United States


Description of Model Variables*

Subclass Variable Description Variable Indexrange

Temporary and seasonal VBCONTINUITY Grassland buffer continuity 0.0 – 1.0

Prairie Pothole VBDENSITY Grassland buffer density 0.0 – 1.0

wetlands, NPPR VBWIDTH Grassland buffer width 0.0 – 1.0

VDETRITUS Detritus 0.0 – 1.0

VOUT Wetland outlet 0.0 – 1.0

VPCOVER Plant cover 0.0 – 1.0

VPIT Excavation 0.0 – 1.0

VPORE Soil porosity 0.0 – 1.0

VPRATIO Ratio of native to nonnative plant species 0.0 – 1.0

VPROXIMITY Proximity to other wetlands 0.0 – 1.0

VSED Sediment delivery to wetland 0.0 – 1.0

VSOM Soil organic matter 0.0 – 1.0

VSOURCE Source area of flow interception 0.0 – 1.0

VSUBOUT Constructed subsurface/surface outlet 0.0 – 1.0

VUPUSE Upland land use 0.0 – 1.0

VWDEN Density of wetlands in the landscape 0.0 – 1.0

VWETAREA Wetland diversity in the landscape 0.0 – 1.0

VWETUSE Wetland land use 0.0 – 1.0

Forested, low-gradient VBTREE Basal area of trees 0.0 – 1.0

riverine wetlands, VCOMP Plant species composition 0.0 – 1.0

CMV and LMAV VCONDUC Saturated hydraulic conductivity 0.0 – 1.0

VCONNECT Connectivity to adjacenthabitats 0.0 – 1.0

VCORE Interior core area 0.0 – 1.0

VCWD Coarse woody debris 0.0 – 1.0

VDETRITUS Primary detrital component 0.0 – 1.0

VDTREE Tree density 0.0 – 1.0

VFREQ Frequency of overbank flow 0.0 – 1.0

VHERB Herbaceous cover 0.0 – 1.0

VLITTER Surfaces for microbial activity 0.0 – 1.0

VLOG Logs 0.0 – 1.0

VMACRO Macrotopographic relief 0.1 – 1.0

VPOND Extent of ponding 0.0 – 1.0

VREDOX Presence of redox soil features 0.0 (Absent)1.0 (Present)

VROUGH Floodplain roughness (Mannings coefficient) 0.1 – 1.0

VSHRUB Density of shrubs 0.0 – 1.0

VSIZE Size of the wetland of which the wetland 0.0 – 1.0assessment area is part

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Description of Model Variables*

Subclass Variable Description VariableIndex range

VSLOPE Flood plain slope 0.1 – 1.0

VSNAGS Density of standing dead trees 0.0 – 1.0

VSOIL Presence of characteristic soil 0.0 – 1.0

VSORPT Sorptive properties of soils 0.0 – 1.0

VSURFCON Surface hydraulic connections 0.0 – 1.0

VWD Woody debris 0.0 – 1.0

VWTD Depth of water table 0.5 – 1.0

VWTGRAD Water table gradient 0.0 – 1.0

VXSEC Floodplain:channel width ratio 0.1 – 1.0

Playa wetlands, VBUFFCON Buffer zone continuity 0.0 – 1.0

High Plains VBUFFWID Buffer zone width 0.0 – 1.0

VCANOPY Plant community canopy 0.0 – 1.0

VDETRITUS Detritus 0.0 – 1.0

VLANDSP Landscape condition 0.0 – 1.0

VMICRO Wetland microtopography 0.25 – 1.0

VMOD Excavation or qther modification to wetland basin 0.1 – 1.0

VPDEN Wetland plant density 0.25 – 1.0

VPORE Soil quality within 50 cm of wetland soil surface 0.0 – 1.0

VPRATIO Ratio of native to non-native plants 0.0 – 1.0

VSED Sediment pelivered to petland 0.0 – 1.0

VSORED Source prea flow interception 0.0 – 1.0

VSOADD Source area flow addition 0.0 – 1.0

VUPUSE Upland land use 0.0 – 1.0

VWDEN Wetland density 0.0 – 1.0

VWETUSE Wetland land use 0.0 – 1.0

* For more information on the three subclass models applied, contact:Temporary and Seasonal Prairie Pothole Wetlands, NPPR:

Rodney O’Clair, NRCS, North Dakota State Office, 701/252-2135, email [email protected]

Forested, Low-Gradient Riverine Wetlands, CMV and LMAV:

CMV – Chris Hamilton, NRCS, Missouri State Office, 573/876-9416, email [email protected];LMAV – Sam Davis or Delaney Johnson, Mississippi State Office, 601/634-7996

email: [email protected] or [email protected]

Playa Wetlands, High Plains:

Robert Schiffner, NRCS, Kansas State Office – Dodge City Area Office, 316/227-3431,email: [email protected]; also http://www.pwrc.usgs.gov/wlistates/playas2.htm.

C–1

Appendix CRestoration Site FCI Values at T0 and T1

Figures 1 through 28 of appendix C show theFuntional Capacity Index (FCI) values for each resto-ration site by subclass and function. The y axis islabeled FCI and is the calculated Functional CapacityIndex for T0 and T1. The x axis is the site label. Thekey for the site label is as follows:

Region ID:

NPPR Northern Prairie Pothole RegionLMAV Lower Mississippi Alluvial ValleyCMV Central Mississippi ValleyHP High Plains

State abbreviation: (used only for LMV and HP)AR ArkansasKS KansasLA LouisianaMO MissouriMS Mississippi

Sequential site ID number:

First two digits, beginning with 01

Site age:

Last two digits in site label

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