U.S. Fish & Wildlife Service

A Conceptual Approach 

to Evaluating Grassland 

Restoration Potential 

on Huron Wetland 

Management District, 

South Dakota

Biological Technical Publication

BTP-R6016-2012

Laura Hubers, USFWS
ISBN-10: 193895601X 

ISBN-13: 978-1-938956-01-0 
i

U.S. Fish & Wildlife Service

A Conceptual Approach 

to Evaluating Grassland 

Restoration Potential 

on Huron Wetland 

Management District, 

South Dakota

Biological Technical Publication

BTP-R6016-2012

Murray K. Laubhan 1

Bridgette Flanders-Wanner 2, 4

Rachel A. Laubhan 3

1

 U.S. Fish and Wildlife Service, Region 6, Division of Biological 

Resources, Stafford, KS

2

 U.S. Fish and Wildlife Service, Huron Wetland Management District, 

Huron, SD

3

 U.S. Fish and Wildlife Service, Quivira National Wildlife Refuge, 

Stafford, KS

4

 Current Address: U.S. Fish and Wildlife Service, Branch of Refuge 

Biology, Vancouver, WA

Cover image: Waubay National Wildlife Refuge

Photo credit: Laura Hubers, USFWS 
ii A Conceptual Approach to Evaluating Grassland Restoration Potential

Author Contact Information:

Murray K. Laubhan

U.S. Fish and Wildlife Service, Region 6

Division of Biological Resources

1434 NE 80th Street

Stafford, KS 67578

Phone: (620) 486-2393

E-mail: Murray_Laubhan@fws.gov

Bridget Flanders-Wanner

U.S. Fish and Wildlife Service, Region 1

Branch of Refuge Biology

1211 SE Cardinal Court, Suite 100

Vancouver, WA 98683

Phone: (360) 604-2558

E-mail: Bridgette_Flanders-Wanner@fws.gov

Rachel A. Laubhan

U.S. Fish and Wildlife Service

Quivira National Wildlife Refuge

1434 NE 80th Street

Stafford, KS 67578

Phone: (620) 486-2393

E-mail: Rachel_Laubhan@fws.gov

Recommended citation:

Laubhan, M. K., B. Flanders-Wanner, and R. A. 

Laubhan. 2012. A conceptual approach to evaluating grassland restoration potential on Huron 

Wetland Management District, South Dakota. U.S. 

Department of Interior, Fish and Wildlife Service, Biological Technical Publication FWS/BTPR6016-2012, Washington, D.C. 

For additional copies or information, contact:

Wayne J. King

Chief, Division of Biological Resources

U.S. Fish and Wildlife Service, Region 6

P.O. Box 25486

Denver Federal Center

Denver, CO 80225-0486

Phone: (303) 236-8102

E-mail: wayne_j_king@fws.gov

Series Senior Technical Editor:

Stephanie L. Jones

Nongame Migratory Bird Coordinator

U.S. Fish and Wildlife Service, Region 6

P.O. Box 25486 DFC

Denver, Colorado 80225

Phone: (303) 236-4409

E-mail: Stephanie_Jones@fws.gov

ISSN 2160-9498 Electronic ISSN 2160-9497 Biological Technical Publications online: 

http://library.fws.gov/BiologicalTechnicalPublications.html
Table of Contents iii

Table of Contents

List of Figures ......................................................................................................................................................... iv

List of Tables ........................................................................................................................................................... v

Acknowledgements .............................................................................................................................................. vi

Executive Summary ............................................................................................................................................. vii

Introduction ............................................................................................................................................................ 1

Review of the Literature ......................................................................................................................................... 3

Goal and Objective Setting ................................................................................................................................. 3

Spatial Scale........................................................................................................................................................... 3

Temporal Scale ..................................................................................................................................................... 3

Abiotic and Biotic Factors ................................................................................................................................... 4

Study Site ............................................................................................................................................................... 5

Conceptual Approach ............................................................................................................................................ 7

Goal and Objectives ............................................................................................................................................. 7

Spatial Scale.......................................................................................................................................................... 7

Temporal Scale ..................................................................................................................................................... 8

Abiotic and Biotic Factors ................................................................................................................................... 8

 Climate .............................................................................................................................................................. 9

 Soils .................................................................................................................................................................... 9

 Topography ...................................................................................................................................................... 10

 Vegetation ......................................................................................................................................................... 10

 Wildlife ............................................................................................................................................................. 11

Framework Development ...................................................................................................................................... 13 

Conclusions .......................................................................................................................................................... 15 

Literature Cited .................................................................................................................................................... 17
iv A Conceptual Approach to Evaluating Grassland Restoration Potential

List of Figures

Figure 1. Level IV ecoregions in the eight-county region of the Huron Wetland Management District, 

South Dakota (modified from Bryce et al. 1998). ...................................................................................................... 5

Figure 2. Simplified illustration of seed bank dynamics, including state variables (rectangles), primary 

abiotic and biotic factors (octagons) influencing plant germination cues and survival (ovals), and common 

examples of anthropogenic factors influencing abiotic and biotic factors (pentagons). Figure adapted from 

Simpson et al. 1989. .................................................................................................................................................... 9

Figure 3. A conceptual approach for evaluating restoration potential of grasslands ........................................ 14
Name of Section List of Tables v

List of Tables

Table 1. Native and non-native species composition of native sod and planted native tracts administered by 

Huron Wetland Management District, South Dakota, in 2003 (BFW). ............................................................... 5

Table 2. Dominant topographic features, soil properties, and climate conditions occurring in level IV 

ecoregions that comprise Huron Wetland Management District (data from Bryce et al. 1998). ..................... 7
vi Status Review and Conservation Recommendations for the Gull-billed Tern

Acknowledgements

W. J. King provided funding and coordinated 

activities associated with this report. The staff of 

the Huron Wetland Management District conducted 

a tour of district lands, summarized existing data, 

and openly discussed management opportunities 

and constraints that should be considered in 

developing a conceptual management approach. 

Reviews of earlier drafts greatly improved the 

report, particularly those provided by D. Azure, P. M. 

Drobney, J. S. Gleason, R. A. Gleason, K. W. Kelsey, 

W. J. King, and C. Mowry. M. J. Artmann kindly 

assisted in the development of tables and figures. 

The findings and conclusions in this article are those 

of the authors and do not necessarily represent the 

views of the U.S. Fish and Wildlife Service.

vi A Conceptual Approach to Evaluating Grassland Restoration Potential 
Executive Summary Name of Section vii

Executive Summary

The 1997 National Wildlife Refuge System 

Improvement Act requires each administrative unit 

in the National Wildlife Refuge System to develop 

a Comprehensive Conservation Plan (CCP). As 

part of this planning process, biological goals and 

objectives must be developed based on the best 

available scientific information. To assist with 

the CCP process, Huron Wetland Management 

District (WMD) requested assistance in developing 

a conceptual approach for evaluating ecological 

restoration options of grassland tracts administered 

by the district. Our approach was to summarize and 

organize general concepts in a framework that could 

be used to evaluate restoration potential rather than 

attempt to develop management recommendations 

that included specific planting techniques or 

management strategies, although this also will be 

required to ensure long-term success. 

We developed our approach based on a review of 

the literature to identify attributes that influenced 

the success of past ecological restoration efforts. 

We developed summaries of this information to 

provide managers and biologists with an overview 

of factors to consider when evaluating restoration 

potential. Development of clear and unambiguous 

goals and objectives was identified as a critical initial 

consideration because they define expectations, help 

determine strategies to be implemented, and form 

the foundation of meaningful monitoring programs. 

Consideration of scale (both spatial and temporal) 

and biological factors (both abiotic and biotic) also is 

important. Collectively, these attributes are useful 

for determining the causes of grassland degradation, 

defining the restoration potential of a site, and 

identifying the most appropriate remediation 

techniques. 

We used these general concepts and attributes 

to develop a conceptual hierarchical framework 

for evaluating restoration potential of individual 

grassland tracts on Huron WMD, which encompasses 

approximately 17,790 km2

 (6,869 mi2) in portions of 

eight counties in east-central South Dakota. District 

staff currently manages 4,644 ha (11,476 ac) of 

grasslands, including 2,537 ha (6,270 ac) that have 

never been tilled and are classified as native sod. 

A focus of upland management is reconstructing 

grasslands on previously farmed sites and restoring 

existing grasslands (i.e., native sod with no 

previous cropping history) that have been invaded 

by non-native grasses to more native vegetation 

communities. 

The goal of ecological restoration on Huron WMD 

is to restore native grasses and forbs that provide 

the structure and resources necessary to support 

populations of target migratory birds. However, 

objectives had not yet been developed that identified 

specific, measurable targets regarding plant 

community composition or wildlife species. Thus, we 

applied our approach to a set of example objectives 

that included developing appropriate seed mixtures 

for reconstruction projects that benefit migratory 

birds, estimating the potential for non-native plant 

species establishment, and determining wildlife 

values that would be expected following restoration. 

The framework we developed incorporated 

attributes that could be used to assess site conditions 

relative to the objectives as well as interim steps 

that provide examples of how attribute information 

can be combined to facilitate evaluation. Finally, 

outcomes based on evaluation of the attributes are 

identified to provide a means to assign priorities to 

restoration projects.

Developing an approach for evaluating and 

prioritizing sites for restoration is a complex 

and uncertain process. Although much is known 

regarding factors controlling plant community 

establishment and the relationships between 

plant communities and wildlife habitat suitability, 

the relative importance of these factors often 

varies among and within sites depending on 

past perturbations and surrounding landscape 

conditions. Consequently, a structured framework 

can promote standardized evaluations and improve 

communication on site, while providing a method to 

systematically deconstruct complex problems and 

provide greater objectivity when making restoration 

decisions.
viii Status Review and Conservation Recommendations for the Gull-billed Tern viii A Conceptual Approach to Evaluating Grassland Restoration Potential 

© Chris Bailey
Name of Section 1

Introduction

The 1997 National Wildlife Refuge System 

Improvement Act requires each administrative unit 

in the National Wildlife Refuge System to develop 

a Comprehensive Conservation Plan (CCP) that 

includes biological goals and objectives that are based 

on the best available scientific information. Goals are 

general descriptions of desired future conditions, but 

objectives are more specific and must be measurable, 

achievable, results oriented, and time specific. In 

many cases, objectives are habitat-based and specify 

the guilds of wildlife species that will benefit from 

attainment of each objective. 

To assist with the CCP process, Huron Wetland 

Management District (WMD) requested that we 

synthesize information on ecological restoration 

approaches for grasslands that would help them 

develop goals and objectives to achieve a desired 

grassland condition defined as a “a mixture of 

native grasses and forbs that provide the structure 

and foods necessary to support target migratory 

bird species.” We decided the best approach was 

to integrate relevant information from different 

scientific disciplines into a framework that could 

be used to evaluate ecological restoration potential 

of different grassland tracts. Although some 

information we used is based on studies conducted 

outside the northern Great Plains, they were relevant 

to Huron WMD because they addressed ecological 

drivers (e.g., soils, moisture, and climate) that are 

primary determinants of plant germination and 

survival regardless of geographic location (Simpson 

et al. 1989, Aronson and Le Floc’h 1996, Ehrenfeld 

2000). 

The desired outcomes used in the document are 

examples developed by the authors and are not those 

of Huron WMD. This document is not intended 

to serve as a complete guide that includes postestablishment management recommendations, but 

as an example of the process. Consequently, on-theground experience in restoring sites, in combination 

with the literature used in the report, should be used 

to evaluate the relevancy of the goals, attributes used 

to evaluate site conditions, and desired outcomes.

Introduction 1
2 Status Review and Conservation Recommendations for the Gull-billed Tern

Review of the Literature

Goal and Objective Setting

The rapid rise of ecological restoration has resulted 

in widely varying interpretations regarding what 

is meant by the term and what constitutes success 

(Palmer et al. 1997, Ruiz-Jaen and Aide 2005). Some 

individuals advocate that restoration is as much ethical 

as technical and should include historical, social, 

cultural, political, aesthetic, and moral aspects, as well 

as ecological principles (Higgs 1997). Even within a 

single discipline such as ecology, restoration can range 

from a focus on particular species to entire ecosystems 

(Risser 1995, Falk et al. 1996, Kershner 1997). These 

different approaches can result in widely varying 

goals and objectives. Strict definitions of restoration 

often have goals that refer to historic conditions and 

objectives that mention emulating the structure, 

function, diversity, and dynamics of the pre-defined 

ecosystem (Aronson et al. 1993). Achieving this level of 

success is rare because it is difficult both to determine 

the exact structure and function of historic ecosystems 

and to establish the full complement of species and 

range of occurrence levels historically present (Cairns 

1991, Lockwood and Pimm 1999). Consequently, some 

practitioners have recommended evaluating restoration 

projects in terms of achieving functional (e.g., erosion 

control) or structural (e.g., species composition) goals 

and objectives (Whisenant 1999, Piper and Pimm 

2002), whereas others advocate defining restoration 

categories (e.g., restoration, rehabilitation, reallocation) 

that have different goals and objectives (Aronson et 

al. 1993, Keddy 1999). In these latter scenarios, goals 

do not necessarily bear an intrinsic relationship with 

pre-disturbance ecosystem structure and function and 

may even consist of innovative combinations of native or 

introduced species (D’Antonio and Meyerson 2002). 

Given this disparity, developing goals and explicit 

objectives is the first and most important component of 

a project. Clear and unambiguous goals and objectives 

define expectations, help determine strategies to be 

implemented, and form the foundation of meaningful 

monitoring programs. Ehrenfeld (2000) discusses 

some common restoration goals and objectives, the 

implications of each from a practical perspective, and 

suggests that there is no single paradigm or context 

for setting goals and objectives; rather, goals and 

objectives need to be developed for each project relative 

to desired outcomes (Jordan et al. 1987, Buckley 1989). 

In addition, goals and objectives should be established 

based on a realistic expectation of what restoration 

can accomplish. Factors to consider include extent 

of degradation, information available for addressing 

problems, and costs (Society of Ecological Restoration 

2004). Ensuring that goals are realistic often can be 

addressed by defining categories of restoration success 

such as those described by Aronson et al. (1993). 

Spatial Scale

The importance of various abiotic and biotic factors in 

developing restoration goals and approaches can vary 

depending on the spatial scale considered (Aronson and 

Le Floc‘h 1996, Goldstein 1999). Reducing or removing 

sources of degradation that compromise system 

functionality often is recommended as an initial step in 

ecological restoration to ensure long-term sustainability 

(Whisenant 1995). Identifying the source of degradation 

is important because the presence or absence of a plant 

or animal species in a specific area may be controlled 

by factors operating at scales much larger than the site 

being evaluated for management (Byre 1997, White and 

Walker 1997, George and Zack 2001). Understanding 

the extent of degradation also is critical as more human 

intervention often is required as degradation increases 

and eventually it may not be possible to completely 

reverse some damages. This concept, termed 

thresholds of environmental change, is well established 

in ecology (Holling 1973, Wissel 1984) and is being 

applied in range management (Friedel 1991, Laylock 

1991) to evaluate site conditions. Failure to consider 

these scale-dependent factors can lead to erroneous 

conclusions regarding remediation techniques, the most 

appropriate plant species to restore, and, ultimately, the 

ability of restoration projects to achieve intended goals. 

Temporal Scale 

Natural systems, including grasslands, are extremely 

dynamic (Pickett and Parker 1994) and considerable 

evidence indicates feedback occurs between species 

composition and ecosystem processes. This feedback 

causes many ecosystem processes to develop over 

different time scales (Palmer et al. 1997, Kulmatiski 

et al. 2006). Consequently, many communities exist in 

perpetual states of nonequlibirium (Wiens 1984, Pickett 

et al. 1992) and exhibit both physical and biological 

variability (Horne and Schnieder 1995, Palmer and 

Poff 1997). Perennial plant species tend to dominate 

both terrestrial and aquatic systems during relatively 

stable periods, whereas annuals tend to predominate 

following shorter temporal scales. At shorter temporal 

scales, dramatic changes in plant composition (e.g., forb 

diversity) also can occur from late spring to winter in 

the same year. 

2 A Conceptual Approach to Evaluating Grassland Restoration Potential 
Review of the Literature Name of Section 33 

Although dynamic conditions are difficult to describe 

succinctly, temporal changes in plant community 

composition and structure are important considerations 

when evaluating ecological restoration potential 

and developing management strategies. Successful 

establishment of a target plant community may require 

the use of certain plant species, such as nitrogen-fixing 

legumes in arid and semi-arid ecosystems, at specific 

times during the restoration process (Jenkins et al. 

1987, Jarrell and Virginia 1990, Paine 1996). Long-term 

sustainability of a plant community also requires that 

sufficient plant diversity be present to persist across the 

full range of environmental fluctuations characteristic 

of the site (Schulze and Mooney 1993, Davis and 

Richardson 1995, Palmer et al. 1997). Adequately 

incorporating the temporal dynamics of ecological 

restoration projects may require a sequential, multistep process or defining the “potential” of a site at 

different stages of succession based on climate, soils, 

hydrology, seed type and availability, plant competition, 

plant-animal interactions, and other factors (Palmer et 

al. 1997).

Abiotic and Biotic Factors

Although restoration goals can focus on a range of 

outcomes, a principle common to most restoration 

approaches is the need to incorporate knowledge of 

processes (Ehrenfeld 2000). Not only is knowledge of 

processes (e.g., hydrology, nutrient cycling) necessary 

to evaluate the full range of remediation measures 

available, this knowledge is also critical to evaluating 

outcomes (King and Hobbs 1996, Montalvo et al. 1997) 

and, ultimately, to developing improved, site-specific 

restoration methods (Ehrenfeld 2000). However, 

ecological processes are complex assemblages of 

interacting factors and direct measurement is often 

not feasible. Therefore, indicators often must be used 

as surrogate measures to assess abiotic and biotic 

site conditions. Knowledge of landscape position, soil 

physical structure and chemistry, and climate often 

can be used to determine the range of soil moisture 

conditions occurring at a site. 

The specific abiotic factors to consider when developing 

an approach to evaluate ecological restoration potential 

are best determined by the goals that have been 

established. A literature review documented that 

factors considered in different projects were diverse 

and tended to be individualistic (Ehrenfeld 2000). 

However, from a management perspective, goals alone 

often are not sufficient to limit the number of factors to 

a manageable level and additional criteria must be used 

to narrow the selection to those that are most relevant. 

Several articles addressing this subject have been 

published, including a list of vital ecosystem attributes 

(Aronson et al. 1993), information syntheses that 

provide general guidance (Whisenant 1995), and several 

practical case histories (Tongway and Ludwig 1996, 

Eliason and Allen 1997, Breshears et al. 2001, Sheley 

and Krueger-Mangold 2003, King and Hobbs 2006). 

A common feature of these articles is the importance 

placed on identifying key abiotic and biotic factors 

related to system structure and function in the context 

of stated goals. 

Bridgette Flanders-Wanner (USFWS)
4 Status Review and Conservation Recommendations for the Gull-billed Tern

and Japanese brome (B. japonicus) occur as 

scattered inclusions, whereas introduced forbs 

include sweet clover (Melilotus spp.) and alfalfa 

(Medicago sativa). The primary noxious weeds 

include leafy spurge (Euphorbia esula), Canada 

thistle (Cirsium arvense), sow thistle (Sonchus 

oleraceus), and wormwood (Artemesia spp.) (BFW).

Management of Huron WMD uplands are primarily 

directed toward reconstructing grasslands on 

previously farmed sites and restoring existing 

grasslands (i.e., native sod with no previous cropping 

history) that have been invaded by non-native 

grasses to more native vegetation communities. 

Reconstruction of previously farmed sites typically 

begins with cropping for two years to promote a seed 

bed that is relatively free of weeds. Corn (Zea mays) 

is typically planted in the first year and soybeans 

(Glycine max) in the second year. Soybeans are 

used in the second year because this crop results 

in a firm seedbed with little crop residue, which 

facilitates reseeding native grass the following 

spring. Approximately three years after an area has 

been reseeded, some type of management is needed 

to remove excess dead vegetation and stimulate 

growth of planted natives. In contrast, grassland 

restoration efforts attempt to shift the composition of 

the existing plant community to a higher proportion 

of native species and do not involve mechanical 

disturbance of soil and use of crops. 

The most common management treatments used 

in both reconstruction (following initial seeding) 

and restoration of Huron WMD grasslands are 

prescribed fire, grazing, or a combination of these 

strategies (BFW). Prescribed fire was used to treat 

2,147 ha (5,305 ac) between 1999 and 2005, whereas 

grazing and a combination of grazing and fire was 

implemented on 1,240 ha (3,064 ac) and 1,414 ha 

(3,494 ac), respectively, between 2000 and 2005 

(BFW). The effectiveness of these treatments in 

stimulating native species and reducing the incidence 

of non-native species varied depending on location, 

vegetation community, and time and intensity of 

treatment. 

Huron WMD was established on May 31, 1992 

under the authority of the Migratory Bird Hunting 

and Conservation Stamp Act (16 U.S.C. 718), 

which authorizes the acquisition, lease, purchase, 

or exchange of small wetland and pothole areas 

designated as Waterfowl Production Areas (WPA). 

Huron WMD encompasses eight counties in eastcentral South Dakota, an area of approximately 

17,790 km2

 (6,869 mi2) (Fig. 1). In 2000, lands 

administered by Huron WMD included 60 WPAs 

(5,807 ha [14,350 ac]), 1,425 wetland easements 

(27,843 ha [68,800 ac]), 147 grassland easements 

(22,541 ha [55,700 ac]), and 63 conservation 

easements (4,087 ha [10,100 ac]) (U.S. Fish and 

Wildlife Service 2000). Although at least one WPA is 

located in every county, the majority occur in Beadle, 

Hand, and Jerauld counties (Fig. 1).

Huron WMD currently manages 4,644 ha (11,476 

ac) of grasslands, including 2,537 ha (6,270 ac) that 

have never been tilled and are classified as native 

sod (Table 1). Approximately 2,411 ha (95% [5,957 

ac]) of native sod are dominated by more than 50% 

non-native species, whereas only 126 ha (5% [311 ac]) 

are dominated by more than 50% native species. The 

remaining 2,107 ha (45% [5,206 ac]) of grasslands are 

comprised of tracts that have been reseeded to native 

plants (713 ha [1,762 ac]) or have been subjected to 

some type of agricultural land-use practice (1,394 

ha [3,444 ac]). Based on surveys of vegetation 

composition on a portion of planted native tracts, it is 

estimated that 521 ha (73% [1,287 ac]) are comprised 

of >50% native species and 192 ha (27% [475 ac]) are 

comprised of <50% native species (Table 1). 

Huron WMD lands include both cool-season native 

grasses dominated by green needlegrass (Nassella 

viridula), western wheatgrass (Pascopyrum 

smithii), and porcupinegrass (Hesperostipa spartea) 

and warm-season grass dominated by big bluestem 

(Andropogon gerardii), switchgrass (Panicum 

virgatum), Indiangrass (Sorghastrum nutans), 

and little bluestem (Schizachyrium scoparium) 

that are intermixed with various native forb 

species. The most common introduced terrestrial 

species are smooth brome (Bromus inermis), 

Kentucky bluegrass (Poa pratensis), and crested 

wheatgrass (Agropyron cristatum). These are 

perennial, sod-forming, cool-season species that 

are drought resistant. In addition, tall wheatgrass 

(Thinopyrum ponticum), intermediate wheatgrass 

(T. intermedium), pubescent wheatgrass, quackgrass 

(Elymus repens), downy brome (Bromus tectorum), 

4 A Conceptual Approach to Evaluating Grassland Restoration Potential 

Study Site
Review of the Literature Name of Section 55 

Figure 1. Level IV ecoregions in the eight-county region of the Huron Wetland Management District, South 

Dakota (modified from Bryce et al. 1998).
6 6 A Conceptual Approach to Evaluating Grassland Restoration Potential Status Review and Conservation Recommendations for the Gull-billed Tern

Conceptual Approach

Goal and Objectives

The goal of restoring native grasses and forbs that 

provide the structure and resources necessary to 

support target migratory birds was used as guidance 

in developing the conceptual approach. Although 

this goal contains general measures of success, 

ecological restoration is still subject to interpretation 

because general descriptions of plant community 

composition (i.e., native grasses and forbs) may 

not explicitly define expectations of restoration. 

Approximately 988 species of native vascular plants 

occur in the tall-grass prairie of the central United 

States and adjacent Canada (Ladd 1997); however, 

a given site is not suitable for all of these species. 

In addition, non-native species dominate many 

sites designated for restoration and long-term, 

complete eradication often is not possible (Society 

of Ecological Restoration 2004). Some tolerance 

threshold for the non-native species may need to 

be established, particularly on small restoration 

projects that are located in highly modified 

landscapes (D’Antonio and Meyerson 2002, Wilson 

and Pärtel 2003). Plant species or plant species 

groups important for providing necessary structure 

and foods for target bird species should be identified 

because habitat requirements of these species 

differ depending on species, annual cycle event, 

climate, and land-use conditions in the surrounding 

landscape (Knopf and Samson 1995, Johnson and 

Igl 2001, Hobbs and Norton 2004). These plant 

species may not represent the entire complement 

of desirable species, but they do represent critical 

community components necessary for success. 

Consequently, specific species or guilds must be 

identified to ensure that the target plant community 

achieves the purposes for which Huron WMD was 

established. Finally, all metrics that will be used to 

define success in achieving goals should be explicitly 

stated. This goal only addresses biological aspects 

even though political and cultural aspects also must 

be considered, and often may override biological 

considerations, when making decisions regarding 

ecological restoration of some sites. 

The existing description of desired condition 

provides sufficient detail to develop an example 

framework to evaluate ecological restoration 

potential. However, if such an approach is used, 

developing specific objectives that explicitly state 

desired outcomes will be necessary to make cohesive 

decisions regarding restoration priorities. Such 

criteria also will be necessary to design a monitoring 

program that can be used to periodically assess 

progress and make sequential decisions regarding 

the most appropriate strategies to implement. 

Spatial Scale

The dynamic attributes of ecosystems, including 

interactions among organisms and between 

organisms and their environment, tend to be 

multi-scaled (Lewis et al. 1996) and this must be 

considered when evaluating ecological restoration 

potential and possible strategies. At a large 

spatial scale, Huron WMD encompasses portions 

of five Level IV ecoregions (Bryce et al. 1998; Fig. 

1). All of these ecoregions are dominated by soils 

in the Order Mollisol with the exception of the 

River Breaks, which also includes Aridisols and 

Entisols. Long-term average annual precipitation 

and annual growing season days also appear similar 

among ecoregions, but closer inspection reveals that 

combinations of these factors result in important 

differences among ecoregions that are reflected in 

soil Great Groups (i.e., differentiations within a soil 

Order based on dominant processes [e.g., drainage]), 

as well as soil temperature and moisture regimes 

(Table 2). This information is valuable for evaluating 

ecological restoration potential because these factors 

can influence vegetation community composition 

and structure at larger spatial scales. The James 

River Lowland and the Missouri Coteau in the north 

central portion of Huron WMD historically supported 

vegetation transitional between tall-grass and mixedgrass prairie and dominated by big bluestem, little 

bluestem, switchgrass, Indiangrass, porcupinegrass, 

green needlegrass, and prairie junegrass (Koeleria 

macrantha). In contrast, ecoregions in the western 

portion of Huron WMD (Southern Missouri Coteau 

Slope, Southern Missouri Coteau, and River 

Breaks) exhibit mesic soil temperatures and ustic 

soil moisture regimes. Historically, vegetation 

in these ecoregions was dominated by species 

characteristic of the mixed-grass prairie, including 

western wheatgrass, green needlegrass, needleand-thread (Hesperostipa comata), little bluestem, 

and blue grama (Bouteloua gracilis). In addition to 

these grasses, the natural vegetation of the River 

Breaks also included juniper (Juniperus spp.) and 

deciduous trees on north slopes and draws, as well 

as cottonwood (Populus spp.) gallery forests on the 

floodplains of the Missouri and James rivers (Gartner 

and Sieg 1996).
Conceptual Approach Name of Section 7
8 8 A Conceptual Approach to Evaluating Grassland Restoration Potential Status Review and Conservation Recommendations for the Gull-billed Tern

Although broad community descriptions can help 

establish general restoration guidelines, abiotic 

and biotic factors also affect plant community 

establishment, composition, and structure at finer 

scales. Within a restoration site, differences in 

soils and climate often occur with subtle changes 

in topography, slope, and aspect. Such differences 

can be sufficient to cause shifts in plant community 

composition and structure across relatively short 

distances. In many cases, these microsites support 

vegetation that is not characteristic of the general 

vegetation community at broader landscape scales. 

Increasing the success of restoration projects 

often requires considering this more site-specific 

information to avoid errors regarding selection of 

plant species to restore and strategies to implement. 

Although a variety of spatial scales could be used 

to develop an approach for evaluating ecological 

restoration potential, we decided to use watersheds 

for Huron WMD lands. Watersheds were selected 

because evaluation at this scale is the most commonly 

cited for setting restoration goals (Ehrenfeld 

2000). Watersheds are applicable to all lands within 

Huron WMD regardless of ecoregion, and most 

lands currently administered by Huron WMD have 

non-integrated drainage and have a well-defined 

watershed (i.e., upland area that drains to an 

isolated wetland) that can be defined using existing 

spatial data. In addition, abiotic factors (e.g., soils, 

topography) that affect ecological functions (e.g., 

nutrient cycling, hydrology) operate at this scale and 

a watershed approach provides the ability to evaluate 

functional changes caused by past land-use activities 

that will be important when developing ecological 

restoration strategies. 

 

Temporal Scale 

Temporal periodicity can significantly influence success 

of ecological restoration efforts because some factors 

controlling plant establishment and persistence exhibit 

considerable variability within and among years. Specific 

combinations of soil temperature, soil moisture, and 

photoperiod are often required to break seed dormancy 

and stimulate seed germination of many species. Climate 

obviously influences these factors and if all requirements 

are not met, germination does not occur during that year. 

Even after initial establishment, these factors continue 

to play a dominant role in determining annual growth, 

survival, and reproduction of plants, as well as the species 

that dominate the plant community. 

It is difficult to explicitly incorporate temporal climate 

variability in an evaluation of restoration potential, but 

considering a range of values (e.g., quantiles, confidence 

intervals) for important variables is often more appropriate 

than using long-term averages. Local or on-site variation 

in monthly precipitation and temperature can be compared 

with the germination and growth requirements of plant 

species when making decisions regarding appropriate 

seed mixtures to plant on specific sites. Such information, 

in combination with the plant species aggregations being 

established or managed and the life history characteristics 

of these species, can also be useful for establishing 

guidelines regarding the proper time to implement various 

management treatments (e.g., soil disturbance, prescribed 

fire, grazing). Although the use of this information does 

not guarantee success, it can help reduce erroneous 

conclusions during the evaluation process. 

Abiotic and Biotic Factors

Establishment of native vegetation suitable to support 

the habitat requirements of target migratory birds is 

the primary consideration in the ecological restoration 

of grasslands on Huron WMD. Most reconstruction 

projects involve planting of seeds, manipulation of 

environmental conditions to stimulate germination 

of seeds already in the seed bank, or a combination 

of these techniques. In contrast, restoration projects 

typically occur in native sod (i.e., areas that have never 

been tilled) and focus on manipulation of existing 

vegetation communities to promote native grasses and 

forbs and suppress non-native species. In both cases, 

understanding processes that control soil propagule 

bank (e.g., seeds, vegetative propagules) and vegetation 

dynamics are paramount (Fig. 2). In general, the 

soil seed bank is comprised of an active and inactive 

component. Seeds (planted or natural) in the active 

component are capable of germination and are located 

in the top 5 cm (2 in) of soil. Seeds in the inactive 

component are buried deeper than 5 cm (2 in) in the soil 

profile and cannot germinate because environmental cues 

stimulating dormancy break and germination are not 

received. Vegetative propagules (e.g., rhizomes, corms) 

also exhibit active and inactive components, although the 

depth of the transition zone tends to occur at greater soil 

depths. The composition and density of propagules in 

the active and inactive components constantly change. 

Propagules already in the soil bank can be moved 

between the active and inactive component by both 

natural (e.g., rodents, water) and anthropogenic (e.g., 

harrowing) factors. In addition, inputs of reproductive 

structures to the soil bank occur annually as a result of 

seed production by plants on the site, propagule dispersal 

(e.g., wind, water, animal) onto the site from nearby 

areas, and by direct addition of propagules by humans. 

Propagule loss occurs from both the active and inactive 

components as a result of pathogens, predation, and 

physiological or physical death. 

Within the active component, only seeds that receive 

appropriate environmental cues germinate. Primary 

cues include photoperiod, soil temperature, soil oxygen, 

soil salinity, and soil moisture (Simpson et al. 1989, 

Baskin and Baskin 1998, Cronk and Fennessy 2001; Fig. 

2). Each of these cues continues to influence survival and 

reproductive potential following germination (Simpson et 

al. 1989), but other factors are also important, including 

nutrient availability, presence of fungal populations, and 

adaptations to disturbance (Miller 1997, Reynolds et al. 

2003, Kulmatiski et al. 2006). Although seemingly simple, 

the pathways controlling germination, establishment, 
Conceptual Approach Name of Section 9

and survival are extremely complex because many 

of the environmental factors influencing germination 

are interrelated; soil temperature tends to increase 

with increasing photoperiod and soil oxygen content 

decreases as soil moisture increases. In addition, many 

germination cues are directly and indirectly influenced 

by other abiotic and biotic factors (Fig. 2) and the 

tolerance of individual species to various environmental 

factors tends to change depending on propagule type 

(e.g., seed, rhizome) and life history stage (e.g., seedling, 

adult). Finally, past human activities (e.g., agriculture) 

have substantially altered interrelationships among 

the factors that influence the short- and long-term 

expression of the plant community. Such changes may 

allow species suited to high resource availability to 

succeed (Davis et al. 2000, Vinton and Goergen 2006) or 

disrupt plant-soil feedback mechanisms that affect plant 

community dynamics, including the invasion potential of 

exotic species (Calderon et al. 2000, Symstad 2000). The 

mixing and turning of soil during plowing stimulates the 

breakdown of soil organic matter and the loss of carbon 

to the atmosphere (Brye and Pirani 2004). The extent of 

this loss can be extensive. In North Dakota, soil carbon 

concentrations in the top 10 cm (4 in) of agricultural 

soils decreased 33% in 25 years (Bauer and Black 1981). 

These changes can significantly affect soil depth, texture, 

and nutrient availability. Tillage also can significantly 

alter moisture gradients by altering topography and the 

hydraulic conductivity of soils (Bouma 1991, Messing and 

Jarvis 1993, Fuentes et al. 2004).

The above discussion focused on the importance of 

environmental conditions in assessing site potential 

relative to plant community germination, establishment, 

and sustainability. Evaluation of the expected value 

of the plant community relative to migratory birds is 

also important given that this was another priority we 

wanted to consider. Ultimately, the avian response to 

management should be evaluated directly through preand post-project monitoring even though species-habitat 

relationships often are used to initially evaluate potential 

responses of target organisms. The most common 

habitat attributes used to conduct such evaluations are 

factors related to area (e.g., minimum area required, 

edge effects, juxtaposition of different habitat types), 

plant structure, and food production, which in turn are 

influenced by plant composition. Habitat suitability, as 

defined by these factors, varies among species and also 

can change for a single species during different annual 

cycle events (e.g., breeding, migration, wintering). Given 

this variability, the most accurate evaluation of potential 

habitat value for migratory birds requires comparing 

anticipated site conditions relative to the requirements 

of multiple species during the appropriate portion of 

the annual cycle. Criteria for selecting a representative 

suit of species can be based on numerous considerations, 

including species mentioned in enabling legislation 

or species of conservation concern that are provided 

in various state, regional, and national conservation 

plans. Given the dynamic nature of grassland plant 

communities, another consideration is to select species 

that represent the full range of vegetation conditions 

that may occur at a site because various attributes, 

Figure 2. Simplified illustration of seed bank dynamics, including state variables (rectangles), primary abiotic 

and biotic factors (octagons) influencing plant germination cues and survival (ovals), and common examples of 

anthropogenic factors influencing abiotic and biotic factors (pentagons). Figure adapted from Simpson et al. 1989.
10 10 A Conceptual Approach to Evaluating Grassland Restoration Potential Status Review and Conservation Recommendations for the Gull-billed Tern

such vegetation structure and types of foods, can differ 

markedly depending on type of disturbance (e.g., fire, 

mowing, herbicide application, soil disturbance) and time 

since the last disturbance occurred. Selecting species 

that characterize a broad range of plant community 

composition and structural requirements will help 

prevent underestimating the avian value of the site. 

Developing this species list may seem overwhelming, 

but it is possible to select a pool of relatively few species 

to represent restoration objectives. While the current 

number of breeding bird species documented in the 

Great Plains is approximately 320 (Johnsgard 1979), 

developing suitable grassland restoration objectives for 

a local area may focus on as few as 32 bird species to 

receive priority consideration (Knopf and Samson 1995).

Huron WMD has yet to develop site-specific information 

on many of the abiotic and biotic factors we identified as 

important for evaluating ecological restoration potential. 

Therefore, we conducted a search to identify potential 

sources of existing information that could be used to 

evaluate site potential during the interim. With respect 

to vegetation, we concentrated on selecting factors that 

influence initial germination and early establishment 

because most management activities conducted on Huron 

WMD directly impact these factors. Incorporation 

of these factors into site evaluations has the potential 

to help determine the extent of degradation, aid in 

developing possible remediation measures, and identify 

appropriate seed mixtures for planting. Many of these 

factors operate at the watershed scale. In contrast, 

factors used to evaluate migratory bird benefits focused 

on defining species-habitat relationships. Although other 

factors influence bird use, species-habitat relationships 

can be directly linked to ecological restoration efforts and 

provide a cohesive method to evaluate potential outcomes 

with the realization that pre- and post-monitoring of the 

avian community also is important. 

Climate.--Climate variables influencing germination and 

early establishment include precipitation, evaporation, 

and ambient temperature, which are primary 

determinants of soil temperature and soil moisture. 

Because these factors exhibit high spatial and temporal 

variability across Huron WMD, site-specific information 

would be valuable. In the absence of local information, 

annual and seasonal ranges could be used to evaluate 

overall site conditions and constraints (High Plains 

Regional Climate Center 2006, National Climatic Data 

Center 2006). 

Soils.--Important characteristics of soils include the 

depth, drainage class, texture, and organic matter 

content of soil horizons (Nelson and Anderson 1983). 

Drainage class (e.g., well drained, moderately well 

drained, very poorly drained) provides a measure of the 

residency time of soil water, whereas texture and organic 

matter content provides a measure of the moisture and 

nutrient retention capacity of soils (Fig. 2). In general, 

soils high in sand tend to retain water for only a short 

period and have lower nutrient concentrations and 

moisture concentrations than soils higher in clay and silt. 

Collectively, these soil properties influence key factors 

that control germination and early establishment of plant 

species. Abrupt discontinuities in species distributions 

can often be explained by differences in soil depth and 

texture (Nelson and Anderson 1983). General soil 

attribute data can be obtained from county soil maps 

and in both tabular and spatial forms (U.S. Department 

Agriculture 2006). 

Topography.--Slope and aspect are among the most 

important topographic variables because they influence 

soil moisture and temperature (Kline 1997). In general, 

slope influences soil moisture gradients, whereas 

aspect influences the time and extent of soil exposure 

to drying winds and sunlight. Steeper slopes tend to 

exhibit steeper soil moisture gradients over a smaller 

area, with low elevations typically being the wettest and 

higher elevations being driest. Within this context, south 

slopes tend to be the hottest and north slopes tend to 

be the coolest. Collectively, these factors can result in 

diverse environmental niches within a watershed that 

support distinct vegetation communities. For example, 

changes in species composition that occur with gradual 

elevation shifts often are due to moisture gradients (Dix 

and Smeins 1967, Clambey and Landers 1978). General 

information on slope and aspect often can be determined 

from a combination of aerial photographs, digital 

elevation models, topography data, or other remotely 

sensed data (U.S. Geological Survey 2006). Depending 

on resolution and data type, subtle differences in 

topography may not be detected and field reconnaissance 

may be required. Equipment necessary to development 

site-specific information is readily available and time 

requirements are minimal to moderate. Additional 

advantages of on-site reconnaissance include groundtruthing soils information and documenting plant species 

composition and distribution.

Vegetation.--Information on climate, soils, and 

topography must be considered in the context of 

plant ecology to be useful in evaluating restoration 

potential. Important plant information includes a list 

of plant species grouped into functional guilds that 

currently or historically occupied sites being considered 

for restoration, knowledge of factors that control 

germination, establishment, and survival of plants 

in each functional guild, and physical traits of plants 

that provide wildlife value. Functional groups can be 

defined using several different classification methods 

(e.g., life form, growth form, metabolic pathway) alone 

or in combination. The most commonly used categories 

include annual/perennial, grass/forb, and cool-season/

warm-season, but other combinations can be developed 

depending on restoration goals. 

Relative to plant germination and establishment, the 

most important factors include type of seed dormancy 

(e.g., none, physical, physiological) and environmental 

conditions required to break seed dormancy (e.g., 

scarification, cold stratification) and stimulate 

germination (Simpson et al. 1989, Baskin and Baskin 

1998, Cronk and Fennessy 2001; Fig. 2). In addition 

to these factors, nutrient and moisture requirements, 

as well as disturbance tolerance are important for 
Conceptual Approach Name of Section 11 

result in the expected response. In general, this could 

occur due to inappropriate timing of a management 

treatment or planting an inappropriate seed mixture. 

Conversely, the lack of response could be caused by 

environmental conditions that are outside human 

control. Differentiating between these causes is difficult, 

but understanding plant germination and growth 

requirements can help prevent drawing inappropriate 

conclusions. In addition, the species or functional species 

groups currently or recently occupying the restoration 

site can provide insight to environmental conditions 

that may influence plant germination and establishment 

(Bever 1994, Reynolds et al. 2003), or indicate potential 

changes in ecological processes or abiotic factors that 

have occurred due to past land use activities (Kulmatiski 

et al. 2006). For example, the presence of droughttolerant species near a stream course could indicate 

a change in soil properties or a disruption in the soil 

moisture gradient.

Numerous approaches can be used to develop lists 

of current and historic plant species. The vegetation 

distribution map and plant community inventory 

produced by Huron WMD are ideal sources for 

developing a list of current plant species, whereas species 

comprising historic communities can be obtained from 

various geographic databases, publications, and surveys 

(e.g., General Land Office, railroad rights-of-way). The 

list of historic species does not need to be exhaustive 

because some species may compensate functionally 

for other species (Naeem et al. 1994, Tilman et al. 

1994, Kindscher and Wells 1995, Piper 1995, Tilman 

1996), but this list should include annuals, perennials, 

determining plant survival (Miller 1997, Reynolds et al. 

2003, Kulmatiski et al. 2006). Physical traits that often 

are important for determining wildlife value include 

growth form, plant height, and food production potential 

(Laubhan et al. 2006).

Collectively, information on the ecology of individual 

plant species can serve several useful purposes. Species 

autecology is important in determining appropriate 

species to plant (reconstruction) and designing 

management treatments (reconstruction and restoration) 

(Simberloff 1990, Vitousek 1990). Seed mixtures 

comprised of more drought-tolerant species may be 

more applicable in semi-arid areas (e.g., south-facing 

hillslopes), whereas a greater complement of mesic 

species may be more appropriate near drainages where 

soil temperatures are cooler and moisture is more 

available. From a management treatment perspective, 

application of fire or grazing should be timed to match 

the appropriate growth stage or annual cycle event of 

plants species being managed. This information can 

be used to time treatments to more effectively control 

undesirable plants (e.g., treatment applied when plant 

species is most vulnerable to stress) or, conversely, to 

stimulate desirable species (e.g., treatment applied 

to increase sunlight penetration and moisture during 

initiation of growth in spring). Knowledge of historic 

and/or current native plant distributions also helps 

define potential species composition at different times 

during the restoration process (Palmer et al. 1997) 

and can be useful in evaluating project success. For 

example, application of a management treatment or seed 

mixture to stimulate certain desirable species may not 

© Chris Bailey
1212 A Conceptual Approach to Evaluating Grassland Restoration Potential Status Review and Conservation Recommendations for the Gull-billed Tern

and keystone species that are functionally important. 

Mutualistic relationships exist between some animals 

(e.g., pollinators) and plant species (Ries and Debinski 

2001, Travers et al. 2011) or certain plant species may be 

involved in the regulation of nutrients important during 

initial establishment (Miller 1997). Following compilation 

of the plant species list, information on plant germination 

and growth requirements of these species can be located 

in electronic databases, reputable websites and seed 

catalogues, books, dissertations, and scientific journals. 

In many cases, information on all important factors will 

not be available for a given plant species. This is not 

problematic because individual species can be grouped 

into functional guilds. 

Wildlife.--Habitat requirements vary depending on the 

species and the annual cycle events that occur on the 

site, but area requirements, nest site characteristics, 

foraging site conditions, and foods are important factors 

in determining habitat quality for many avian species. 

Information on habitat requirements can be obtained 

from numerous sources, including electronic databases, 

literature syntheses, and scientific journals (Laubhan 

et al. 2006), but the quality of data should be evaluated 

relative to the intended purpose of use. Qualitative 

information (e.g., tall, dense) is difficult to use in 

evaluating habitat suitability because it only provides a 

general impression of required conditions. In contrast, 

quantitative measures (e.g., range, confidence intervals) 

are more valuable because they can be compared directly 

to vegetation measures collected on the site. In addition, 

care should be exercised when interpreting off-site 

information because habitat requirements reported from 

different geographic areas may or may not be directly 

applicable to sites on Huron WMD due to differences in 

climate, plant composition, landscape conditions, or other 

factors (Bakker et al. 2002, Laubhan et al. 2008). 
Framework Development Name of Section 1313 

Framework Development

Historically, the development of ecological 

restoration strategies largely has been based on 

knowledge gained from experiments to restore 

degraded landscapes (King and Hobbs 2006). These 

strategies may or may not be successful when 

applied to sites that differ with respect to various 

abiotic and biotic factors, which suggests that 

formulation of a sound restoration approach requires 

more than anecdotal information (Hobbs and Norton 

1996, Choi 2004). Further, increasing the chance of 

project success relative to desired goals requires not 

only the capability to implement various techniques 

(e.g., seed source, equipment), but also developing 

an understanding of when different techniques are 

most applicable. 

To address the considerations described above, 

numerous approaches have been developed to 

evaluate a site and determine the most appropriate 

restoration strategy. One approach is to use 

reference sites (Society of Ecological Restoration 

2004). Comparison of environmental conditions at 

the reference site and degraded site can provide 

valuable insight that can be used to develop realistic 

goals and identify possible restoration scenarios. 

Unfortunately, the utility of reference sites is 

sometimes limited because they are difficult to 

identify and the structure and function of these 

areas may not be known (Michener 1997, White and 

Walker 1997). Another approach, which is used in 

this report, is to develop a decision analysis model 

or schema that focuses on key attributes considered 

critical to restoring structure and function (Aronson 

et al. 1993, Milton et al. 1994, Box 1996, Ludwig 

et al. 1997, Perrow and Davy 2002, Temperton et 

al. 2004). Applicability of such models in a field 

setting requires time- and cost-efficient collection of 

relevant information. In the previous section, ideas 

were provided on sources of data for potentially 

important factors that are already available and 

either free or relatively inexpensive to acquire. In 

some cases, this information may not be of sufficient 

quality and more costly methods of acquiring 

necessary data may be necessary. 

The framework developed for evaluating restoration 

potential on Huron WMD lands is comprised of 

goals, objectives, attributes, and outcomes (Fig. 3). 

The goal represents the purpose of constructing the 

decision model and objectives describe in more detail 

what values will be considered when determining 

priorities. Attributes represent the primary factors 

identified in the previous section that are used to 

assess site conditions relative to the objectives and 

interim steps (ovals) are examples of how attribute 

information can be combined to facilitate evaluation. 

Outcomes (represented by the double boxes in Fig. 3) 

are based on evaluation of the attributes and could be 

used to assign priorities to restoration projects. 

Huron WMD will establish grassland goals and 

objectives during the CCP process that may differ 

somewhat from the general description used 

in this report. As an example, we developed a 

conceptual schema based on the goal of evaluating 

the reconstruction potential of individual WPAs in 

Huron WMD. Obviously, there are numerous other 

objectives (e.g., developing appropriate management 

strategies for restoring native sod communities) 

and attributes that could be included to provide a 

more thorough evaluation. Given that on-site data 

regarding additional attributes on Huron WMD 

lands currently is limited and management decisions 

cannot be postponed until this data is collected, 

© Chris Bailey
14 14 A Conceptual Approach to Evaluating Grassland Restoration Potential Status Review and Conservation Recommendations for the Gull-billed Tern

interrupted the soil moisture gradient along a 

slope. This information could be used to delineate 

and map zones with unique abiotic properties 

in the restoration site that could influence plant 

species composition, ease of establishment, and 

areas where more intensive management may 

be required. Topographically low, poorly drained 

alluvial soils (typically rich in organic matter) that 

would support plants requiring increased soil 

moisture could be separated from adjacent toe-slopes 

with rapid drainage (typically moderate amounts 

of organic matter) that would support more xeric 

species. The environmental characteristics of each 

zone could then be compared with the germination/

reproductive requirements of available plant species 

in the various functional groups to help determine 

appropriate seed mixtures for each zone. The value 

(or priority) of restoring the site could be determined 

by comparing current wildlife values with anticipated 

post-restoration values based on differences in the 

amount of contiguous grassland area provided, plant 

structure, and food resources that would occur if 

restoration is successful. 

we developed our approach based on available 

information to assist Huron WMD in the decision 

process.

Example objectives were designated as developing 

appropriate seed mixtures for reconstruction 

projects that benefit migratory birds, estimating the 

potential for non-native plant species establishment, 

and determining wildlife values that would be 

expected following restoration. To accomplish the 

evaluation, attributes were grouped into three 

categories (abiotic, land-use history, and biotic) to 

aid interpretation. The abiotic attributes include 

topographic and soils data from the watershed 

encompassing the site. In this example, the 

topographic and soils data would be intersected 

using a geographic information system to delineate 

unique combinations of soils, slopes, and aspects. 

In addition, information on altered soil structure 

and/or hydrology caused by past land-use activities 

could be incorporated into this matrix (Fig. 3). Field 

examination could reveal that tillage has caused the 

loss of soil organic matter or aerial photography 

could identify the presence of terraces that have 

Figure 3. A conceptual approach for evaluating restoration potential of grasslands.
Name of Section Conclusions 15

Conclusions

Developing an approach for evaluating and 

prioritizing sites for restoration is a complex 

and uncertain process. Although much is known 

regarding factors controlling plant community 

establishment and relationships between plant 

communities and wildlife habitat suitability, 

the relative importance of these factors often 

varies among and within sites depending on past 

perturbations and surrounding landscape conditions. 

Detailed information regarding many of these 

factors often is limited on specific sites and intra- and 

inter-annual climate variability make it impossible to 

accurately predict future environmental conditions. 

Therefore, it is not possible to develop a single 

restoration strategy that is appropriate for all sites, 

or even all landscape conditions within a site, and 

even management treatments that are appropriately 

tailored to a site may not yield expected results. 

Given this uncertainty, general schemas that 

incorporate abiotic and biotic factors related to the 

dynamic processes influencing plant community 

composition and structure must be developed to 

guide restoration. 

The conceptual framework we developed is 

intended to serve this purpose, but additional work 

must be accomplished before this model could be 

implemented because the objectives used in the 

model are examples developed by the authors and 

the attributes selected for inclusion are based on 

a review of the literature rather than field data 

collected on Huron WMD. Hopefully, Huron WMD 

will continue to develop this approach because a 

conceptual framework assists in the identification of 

attributes important in evaluating outcomes. Most 

individuals recognize the impact of abiotic factors 

and past land use in determining plant community 

composition and structure, but this contributes 

little to developing management approaches if 

specific factors and their relationship to achieving 

goals are not defined. A structured framework 

also promotes standardized evaluations and can 

improve communication as it provides a method to 

systematically deconstruct complex problems and 

provide greater objectivity when making restoration 

decisions (Cipollini et al. 2005). Finally, frameworks 

that incorporate abiotic and biotic factors as primary 

determinants of expected outcomes can facilitate 

implementing an adaptive management process 

(Walters and Holling 1990, Haney and Power 1996). 
16 16 A Conceptual Approach to Evaluating Grassland Restoration Potential Status Review and Conservation Recommendations for the Gull-billed Tern

Literature Cited

Aronson, J., and E. Le Floc’h. 1996. Vital landscape 

attributes: missing tools for restoration ecology. 

Restoration Ecology 4:327-333.

Aronson, J., C. Floret, E. Le Floc’h, C. Ovalle, and 

R. Pontanier. 1993. Restoration and rehabilitation 

of degraded ecosystems in arid and semi-arid lands. 

I. A view from the south. Restoration Ecology 1:8-

17.

Bakker, K. K., D. E. Naugle, and K. F. Higgins. 

2002. Incorporating landscape attributes into 

models for migratory grassland bird conservation. 

Conservation Biology 16:1638-1646.

Baskin, C. C., and J. M. Baskin. 1998. Seeds: 

ecology, biogeography, and evolution of dormancy 

and germination. Academic Press, New York.

Bauer, A., and A. L. Black. 1981. Soil carbon, 

nitrogen, and bulk density comparisons in two 

cropland tillage systems after 25 years and in virgin 

grassland. Soil Science Society of America Journal 

45:1166-1170.

Bever, J. D. 1994. Feedback between plants and 

their soil communities in an old field community. 

Ecology 75:1965-1977.

Bouma, J. 1991. Influence of soil macroporosity on 

environmental quality. Agronomy 46:1-37.

Box, J. 1996. Setting objectives and defining 

outputs for ecological restoration and habitat 

creation. Restoration Ecology 4:427-432.

Breshears, D. D., J. A. Ludwig, S. N. Martens, P. C. 

Beeson, B. P. Wilcox, and C. D. Allen. 2001. Runoff 

and erosion thresholds: implications for rangeland 

degradation and restoration. Ecological Society of 

America Annual Meeting Abstracts 86:8-9.

Bryce, S., J. M. Omernik, D. E. Pater, M. Ulmer, 

J. Schaar, J. Freeouf, R. Johnson, P. Kuck, and S. 

H. Azevedo [Online]. 1998. Ecoregions of North 

Dakota and South Dakota. Northern Prairie 

Wildlife Research Center, Jamestown, North 

Dakota. <http://www.npwrc.usgs.gov/resource/1998/

ndsdeco/ndsdeco.htm> (31 October 2006).

Brye, K. R., and A. L. Pirani. 2004. Native soil 

quality and the effects of tillage in the Grand Prairie 

Region of eastern Arkansas. American Midland 

Naturalist 154:28-41.

Buckley, G. P., editor. 1989. Biological habitat 

reconstruction. Belhaven Press, London, United 

Kingdom.

Byre, V. J. 1997. Birds. Pages 327-337 in S. Packard 

and C. F. Mutel, editors. The tallgrass restoration 

handbook for prairies, savannas, and woodlands. 

Island Press, New York.

Cairns, J., Jr. 1991. The status of the theoretical 

and applied science of restoration ecology. 

Environmental Professional 13:1-9.

Calderon, F. J., L. E. Jackson, K. M. Scow, and D. 

E. Rolston. 2000. Microbial responses to simulated 

tillage in cultivated and uncultivated soils. Soil 

Biology and Biochemistry 32:1547-1559.

Choi, Y. D. 2004. Theories for ecological restoration 

in changing environments: toward ‘futuristic’ 

restoration. Ecological Research 19:75-81.

Cipollini, K. A., A. L. Maruyama, and C. L. 

Zimmerman. 2005. Planning for restoration: 

a decision analysis approach to prioritization. 

Restoration Ecology 13:460-470.

Clambey, G. K., and R. Q. Landers. 1978. A survey 

of wetland vegetation in north-central Iowa. Pages 

32-35 in D. C. Glenn-Lewin and R. Q. Landers, Jr., 

editors. Proceedings of the 5th Midwest Prairie 

Conference, Ames, Iowa.

Cronk, J. K., and M. S. Fennessy. 2001. Wetland plants: 

biology and ecology. Lewis Publishers, New York.

D’Antonio, C., and L. A. Meyerson. 2002. Exotic 

plant species as problems and solutions in ecological 

restoration: a synthesis. Restoration Ecology 10:703-713.

Davis, G. W., and D. M. Richardson. 1995. 

Mediterranean-type ecosystems: the function of 

biodiversity. Springer-Verlag, Berlin, Germany.

Davis, M. A., J. P. Grime, and K. Thompson. 2000. 

Fluctuating resources in plant communities: a 

general theory of invasibility. Journal of Ecology 

88:528-534.

Dix, R. L., and F. E. Smeins. 1967. The prairie, 

meadow, and marsh vegetation of Nelson County, 

North Dakota. Canadian Journal of Botany 45:21-58.
Name of Section Literature Cited 17

Ehrenfeld, J. G. 2000. Defining the limits of 

restoration: the need for realistic goals. Restoration 

Ecology 8:2-9.

Eliason, S. A., and E. B. Allen. 1997. Exotic grass 

competition in suppressing native shrubland reestablishment. Restoration Ecology 5:245-255.

Falk, D. A., C. I. Millar, and M. Olwell, editors. 1996. 

Restoring diversity: strategies for the reintroduction 

of endangered plants. Island Press, Washington, D.C.

Friedel, M. H. 1991. Range condition assessment 

and the concept of thresholds: a viewpoint. Journal 

of Range Management 44:422-426.

Fuentes, J. P., M. Flury, and D. F. Bezdicek. 2004. 

Hydraulic properties in a silt loam soil under natural 

prairie, conventional till, and no till. Soil Science 

Society of America Journal 68:1679-1688.

Gartner, F. R., and C. H. Sieg. 1996. South Dakota 

rangelands: more than a sea of grass. Rangelands 

18:212-216.

George, T. L., and S. Zack. 2001. Spatial and 

temporal considerations in restoring habitat for 

wildlife. Restoration Ecology 9:272-279.

Goldstein, P. Z. 1999. Functional ecosystems and 

biodiversity buzzwords. Conservation Biology 

13:247-255.

Haney, A., and R. L. Power. 1996. Adaptive 

management for sound ecosystem management. 

Environmental Management 20:879-886.

Higgs, E. S. 1997. What is good ecological 

restoration? Conservation Biology 11:338-348. 

High Plains Regional Climate Center [Online]. 2006. 

Current climate summary maps. <http://www.hprcc.

unl.edu> (24 May 2012).

Hobbs, R. J., and D. A. Norton. 2004. Ecological 

filters, thresholds, and gradients in resistance 

to ecosystem reassembly. Pages 72-95 in V. M. 

Temperton, R. J. Hobbs, T. Nuttle, and S. Halle, 

editors. Assembly rules and restoration ecology. 

Island Press, Washington, D.C.

Hobbs, R. J., and D. A. Norton. 1996. Towards 

a conceptual framework for restoration ecology. 

Restoration Ecology 4:93-110.

Holling, C. S. 1973. Resilience and stability of 

ecological systems. Annual Review of Ecology and 

Systematics 4:1-23.

Horne, J. K., and D. C. Schneider. 1995. Spatial 

variance in ecology. Oikos 74:18-26.

Jarrell, W. M., and R. A. Virginia. 1990. Soil cation 

accumulation in a mesquite woodland: sustained 

production and long-term estimates of water use 

and nitrogen fixation. Journal of Arid Environments 

18:51-56.

Jenkins, M. B., R. A. Virginia, and W. M. Jarrell. 

1987. Rhizobial ecology of the woody legume 

mesquite (Prosopis glandulosa) in a Sonoran Desert 

arroyo. Plant and Soil 105:113-120. 

Johnsgard, P. A. 1979. Birds of the Great Plains. 

University of Nebraska Press, Lincoln, Nebraska.

Johnson, D. H., and L. D. Igl. 2001. Area 

requirements of grassland birds: a regional 

perspective. Auk 188:24-34.

Jordan, W. R., M. E. Gilpin, and J. D. Aber, editors. 

1987. Restoration ecology: a synthetic approach to 

ecological research. Cambridge University Press, 

Cambridge, United Kingdom.

Keddy, P. 1999. Wetland restoration: the potential 

for assembly rules in the service of conservation. 

Wetland 19:716-732.

Kershner, J. L. 1997. Setting riparian/aquatic 

objectives within a watershed context. Restoration 

Ecology 5:15-24.

Kindscher, K., and P. V. Wells. 1995. Prairie plant 

guilds: a multivariate analysis of prairie species 

based on ecological and morphological traits. 

Vegetatio 117:29-50.

King, E. G., and R. J. Hobbs. 2006. Identifying 

linkages among conceptual models of ecosystem 

degradation and restoration: towards an integrative 

framework. Restoration Ecology 14:369-378.

Kline, V. M. 1997. Planning a restoration. Pages 

31-46 in S. Packard and C. F. Mutel, editors. The 

tallgrass restoration handbook for prairies, savannas, 

and woodlands. Island Press, New York.

Knopf, F. L. and F. B. Samson. 1995. Conserving 

the biotic integrity of the Great Plains. Pages 

121-133 in S. R. Johnson and A. Bouzaher, editors. 

Conservation of Great Plains ecosystems: current 

science, future options. Kluwer Academic Publishers, 

Dordrecht, The Netherlands.

Kulmatiski, A. K. H. Beard, and J. M. Stark. 2006. 

Soil history as a primary control on plant invasion 

in abandoned agricultural fields. Journal of Applied 

Ecology 43:8868-876.

Ladd, D. 1997. Appendix A: Vascular plants of 

midwestern tallgrass prairies. Pages 351-355 in

S. Packard and C. F. Mutel, editors. The tallgrass 

restoration handbook for prairies, savannas, and 

woodlands. Island Press, New York. 
18 A Conceptual Approach to Evaluating Grassland Restoration Potential Status Review and Conservation Recommendations for the Gull-billed Tern

Montalvo, A. M., S. L. Williams, K. J. Rice, S. L. 

Buchmann, C. Cory, S. N. Handel, G. P. Nabhan, R. 

Primack, and R. H. Robichaux. 1997. Restoration 

biology: a population biology perspective. 

Restoration Ecology 5:277-290.

Naeem, S., L. J. Thompson, S. P. Lawler, J. H. 

Lawton, and R. M. Woodfin. 1994. Declining 

biodiversity can alter the performance of ecosystems. 

Nature 368:734-737.

National Climatic Data Center [Online]. 2006. 

Monthly surface data. National Oceanic and 

Atmospheric Administration, Asheville, North 

Carolina. <http://www.ncdc.noaa.gov/oa/ncdc.html> 

(24 May 2012).

Nelson, D. C., and R. C. Anderson. 1983. Factors 

related to the distribution of prairie plants along a 

moisture gradient. American Midland Naturalist 

109:367-375.

Paine, R. T. 1966. Food web complexity and species 

diversity. American Naturalist 100:65-75.

Palmer, M. A., and N. L. Poff. 1997. The influence 

of environmental heterogeneity on patterns and 

processes in streams. Journal of the North American 

Benthological Society 16:169-173.

Palmer, M. A., R. F. Ambrose, and N. L. Poff. 1997. 

Ecological theory and community restoration ecology. 

Restoration Ecology 5:291-300.

Perrow, M. R., and A. J. Davy, editors. 2002. 

Handbook of ecological restoration. Volume 1. 

Principals of restoration. Cambridge University 

Press, Cambridge, United Kingdom.

Pickett, S. T. A., and V. T. Parker. 1994. Avoiding 

the old pitfalls: opportunities in a new discipline. 

Restoration Ecology 2:75-79. 

Pickett, S.T.A., V. T. Parker, and P. G. Fiedler. 

1992. The new paradigm in ecology: implications 

for conservation biology above the species level. 

Pages 66-88 in P. L. Fiedler and S. K. Sain, editors. 

Conservation biology. Chapman and Hall, New York.

Piper, J. K. 1995. Composition of prairie plant 

communities on productive versus unproductive sites 

in wet and dry years. Canadian Journal of Botany 

73:1635-1644.

Piper, J. K., and S. L. Pimm. 2002. The creation 

of diverse prairie-like communities. Community 

Ecology 3:205-216.

Reynolds, H. L., A. Packer, J. D. Bever, and K. 

Clay. 2003. Grassroots ecology: plant-microbesoil interactions of plant community structure and 

dynamics. Ecology 84:2281-2291.

Laubhan, M. K., K. E. Kermes, and R. A. Gleason. 2008. 

Proposed approach to assess potential wildlife habitat 

suitability on program lands. Pages 45-58 in R. A. 

Gleason, M. K. Laubhan, and N. H. Euliss, Jr., editors. 

Ecosystem services derived from wetland conservation 

practices in the United States Prairie Pothole 

Region with an emphasis on the U.S. Department 

of Agriculture Conservation Reserve and Wetland 

Reserve Programs. U.S. Department of the Interior, 

U.S. Geological Survey Professional Paper 1745.

Laubhan, M. K., R. A. Gleason, N. H. Euliss, Jr., G. 

A. Knutsen, and R. A. Laubhan. 2006. A preliminary 

biological assessment of Long Lake National 

Wildlife Refuge Complex, North Dakota, USA. U.S. 

Department of Interior, Fish and Wildlife Service, 

Biological Technical Publication FWS/BTP R6006-

2006, Washington, D.C.

Laylock, W. A. 1991. Stable states and thresholds 

of range condition on North American rangelands: a 

viewpoint. Journal of Range Management 44:427-433.

Lewis, C. A., N. P. Lester, A. D. Bradshaw, J. E. 

Fitzgibbon, K. Fuller, L. Hakanson, and C. Richards. 

1996. Considerations of scale in habitat conservation 

and restoration. Canadian Journal of Fisheries and 

Aquatic Sciences 53(S1):440-445.

Lockwood, J. L., and S. L. Pimm. 1999. When does 

restoration succeed? Pages 363-392 in E. Weiher and P. 

Keddy, editors. Ecological assembly rules. Cambridge 

University Press, Cambridge, United Kingdom.

Ludwig, J. A., D. J. Tongway, D. Freudenberger, J. 

Noble, and K. Hodgkinson, editors. 1997. Landscape 

ecology, function and management: principles 

from Australia’s rangelands. CSIRO Publishing, 

Melbourne, Australia.

Messing, I., and N. J. Jarvis. 1993. Temporal 

variation in the hydraulic conductivity of a tilled clay 

soil as measured by tension infiltrometers. Journal 

of Soil Science 44:11-24.

Michener, W. K. 1997. Quantitatively evaluating 

restoration “experiments”: research design, 

statistical analysis, and data management 

considerations. Restoration Ecology 5:324-337.

Miller, R. M. 1997. Prairie underground. Pages 

23-27 in S. Packard and C. F. Mutel, editors. The 

tallgrass restoration handbook for prairies, savannas, 

and woodlands. Island Press, New York. 

Milton, S. J., W. R. J. Dean, M. A. Du Plessis, and 

W. R. Siegfried. 1994. A conceptual model of 

arid rangeland degradation: the escalating cost of 

declining productivity. Bioscience 44:70-76.
Name of Section Literature Cited 1919 

Ries, L., and D. M. Debinski. 2001. Butterfly 

responses to habitat edges in the highly fragmented 

prairies of Central Iowa. Journal of Animal Ecology 

70:840-852.

Risser, P. G. 1995. Biodiversity and ecosystem 

function. Conservation Biology 9:742-746.

Ruiz-Jaen, M. C., and T. M. Aide. 2005. Restoration 

success: how is it being measured? Restoration 

Ecology 13:569-577.

Schulze, E.-D., and H. A. Mooney. 1993. 

Biodiversity and ecosystem function. SpringerVerlag, Berlin, Germany.

Sheley, R. L., and J. Krueger-Mangold. 2003. 

Principles for restoring invasive plant-infested 

rangeland. Weed Science 51:260-265.

Simberloff, D. 1990. Community effects of biological 

introductions and their implications for restoration. 

Pages 128-136 in D. R. Towns, C. H. Daugherty, and 

I. A. Atkinson, editors. Engineered organisms in the 

environment: scientific issues. American Society for 

Microbiology, Washington, D.C.

Simpson, R. L., M. A. Leck, and V. T. Parker. 1989. 

Seed banks: general concepts and methodological 

issues. Pages 3-21 in M. A. Leck, V. T. Parker, and 

R. L. Simpson, editors. Ecology of soil seed banks. 

Academic Press, San Diego, California.

Society for Ecological Restoration International 

Science and Policy Working Group (SER). 2004. 

The SER international primer on ecological 

restoration. Society for Ecological Restoration 

International, Tucson, Arizona. <http://www.ser.

org/> (31 October 2006).

Symstad, A. J. 2000. A test of the effects of 

functional group richness and composition on 

grassland invisibility. Ecology 81:99-109.

Temperton, V. M., R. J. Hobbs, T. Nuttle, and S. 

Halle, editors. 2004. Assembly rules and restoration 

ecology: bridging the gap between theory and 

practice. Island Press, Washington, D.C.

Tilman, D. 1996. Biodiversity: population versus 

ecosystem stability. Ecology 77:350-363.

Tilman, D. J., A. Downing, and D. A. Wedin. 1994. 

Does diversity beget stability? Nature 371:257-264.

Tongway, D. J., and J. A. Ludwig. 1996. 

Rehabilitation of semiarid landscapes in Autralia. 

I. Restoring productive soil patches. Restoration 

Ecology 4:388-397. 

Travers, S. E., G. M. Fauske, K. Fox, A. A. Ross, and M. O. 

Harris. 2011. The hidden benefits of pollinator diversity 

for rangelands of the Great Plains: western prairie 

fringed orchids as a case study. Rangelands 33:20-26.

U.S. Department of Agriculture [Online]. 2006. Soil 

attribute data. U.S. Department of Agriculture, 

Natural Resources Conservation Service. <http://

soildatamart.nrcs.usda.gov> (24 May 2012). 

U.S. Fish and Wildlife Service. 2000. South Dakota 

briefing book. Unpublished report. U.S. Department 

of Interior, Fish and Wildlife Service. <http://

moutain-prairie.fws.gov/reference/> (31 October 

2006).

U.S. Geological Survey [Online]. 2006. National 

geospatial program. U.S. Department of Interior, 

Geological Survey. <http://www.usgs.gov/ngpo> (24 

May 2012). 

Vitousek, P. M. 1990. Biological invasions and 

ecosystem processes: towards an integration of 

population biology and ecosystem studies. Oikos 

57:7-13.

Vinton, M. A., and E. M. Goergen. 2006. Plant-soil 

feedbacks contribute to the persistence of Bromus 

inermis in Tallgrass Prairie. Ecosystems 9:967-976.

Walters, C. J., and C. S. Holling. 1990. Large-scale 

managements and learning by doing. Ecology 

71:2060-2068.

Whisenant, S. G. 1995. Landscape dynamics and 

arid land restoration. Pages 26-34 in B. A. Roundy, 

E. McArthur, E. Durant, J. S. Haley, and D. K. Mann, 

compilers. Proceedings: wildland shrub and arid 

land restoration symposium. U.S. Department of 

Agriculture Forest Service General Technical Report 

INT-GTR-315, Ogden, Utah.

Whisenant, S. G. 1999. Repairing damaged 

wildlands: a process-oriented, landscape-scale 

approach. Cambridge University Press, Cambridge, 

United Kingdom.

White, P. S., and J. L. Walker 1997. Approximating 

nature’s variation: selecting and using reference sites 

and reference information in restoration ecology. 

Restoration Ecology 5:338-349.

Wiens, J. A. 1984. On understanding a nonequilibrium world: myth and reality in community 

patterns and processes. Pages 439-457 in D. R. 

Strong, D. Simberloff, L. G. Abele, and A. G. Thistle, 

editors. Ecological communities: conceptual issues 

and the evidence. Princeton University Press, 

Princeton, New Jersey.

Wilson, S. D., and M. Pärtel. 2003. Extirpation or 

coexistence? Management of a persistent introduced 

grass in a prairie restoration. Restoration Ecology 

11:410-416.

Wissel, C. 1984. A universal law of the characteristic 

return time near thresholds. Oecologia 65:101-107.
20 Status Review and Conservation Recommendations for the Gull-billed Tern 20

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U.S. Fish & Wildlife Service

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