Applying Ecological Principles to Land-Use Decision Making in Agricultural Watersheds


     Applying Ecological Principles to Land-Use Decision Making in

                          Agricultural Watersheds
  Mary Santelmann !, Kathryn Freemark2, Denis White3, Joan Nassauer 4, Mark

 Clark5, Brent Danielson 5, Joseph Eilers6, Rick Cruse5, Susan Galatowitsch7, Steve

                       Polasky \ Kellie Vache1, Junjie Wu'



1 Oregon State University, Corvallis, OR 97331

2 Environment Canada, Canadian Wildlife Service, Hull, Quebec, Canada K1A OH3

3 formerly at OSU, now with U.S. Environmental Protection Agency, Corvallis, OR 97330

4 University of Michigan, Ann Arbor, MI 48109

5 Iowa State University, Ames, Iowa 50011

6 formerly at E & S Environmental Chemistry, Inc., now at  JC Headwaters, Inc. Roseburg, OR 97470

7 University of Minnesota, Minneapolis-St. Paul, MN  55455
Keywords: future scenarios, agricultural watersheds, spatially-explicit models
Disclaimer: The information in this document has been funded in part by the US
Environmental Protection Agency.  It has been subjected to the Agency's peer and
administrative review, and it has been approved for publication.

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WED-00-041
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing/
1. REPORT NO.
KPA/600/A-00/023
2.
4. TITLE AND SUBTITLE Applying Ecological principles to land-use decision making
in agricultural watersheds

7. AUTHOR(S) Mary Santelmann ', Kathryn Freemark2, Denis White9, Joan Nassauer4
Mark Clark8, Brent Danielson, Joseph Eilers6 , Rick Cruse5, Susan Galatowitsch 7,
Steve Polasky 7, Kelly Vache1, Junjie Wu.1
9. PERFORMING ORGANIZATION NAME AND ADORE!
'Oregon State University 'University
Corvallis, OR 97331 Ann Arboi
Environment Canada Blowa Stati
Canadian Wildlife Service Ames, low
Hull, Quebec, Canada K1A OH3
'US EPA NHEERL WED "JC Heado
200 SW 35th Street Roseburg
Corvallis, OR 97333
'University of Minnesota
Minneapolis-St. Paul MN 55455
5S
of Michigan
', Ml 481 09
9 University
a 5001 1
uarters, Inc
, OR 97470
12. SPONSORING AGENCY NAME AND ADDRESS
US EPA ENVIRONMENTAL RESEARCH LABORATORY
200 SW 35th Street
Corvallis, OR 97333
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE
6. PERFORMING ORGANIZATION
CODE
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15. SUPPLEMENTARY NOTES:
16. ABSTRACT: The Ecological Society of America on sustainable Land Use has put together a set of ecological principles and guidelines to
help in land-use decision making. The practical application of these principles and the associated guidelines to planning efforts in real
landscapes will require the development and use of strategies and tools to translate them into specific sets of land-use practices (Riparian
buffers, floodplain and wetland restorations, etc) and ways to place these practices effectively on the landscape. In this chapter, we discuss
the use of future scenarios coupled with Geographic Information Systems (GIS) based evaluative models as a methodology for effective land-
use planning. We demonstrate the application of this method to explore alternative futures for two agricultural watersheds in the U.S. Combeft.
17.
a. DESCRIPTORS
future scenarios, agricultural watersheds,
spatially-explicit models
18. DISTRIBUTION STATEMENT
KEY WORDS AND DOCUMENT ANALYSIS
b. IDENTIFIERS/OPEN ENDED
TERMS

19. SECURITY CLASS (This Report)
c. COSATI Field/Group

21. NO. OF PAGES: 33

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" When we see land as a community to which we belong, we may begin to use it with love and respect.
There is no other way for land to survive the impact of mechanized man, nor for us to reap from it OK
esthetic harvest it is capable, under science, of contributing to culture. That land Is a community is the
basic concept of ecology, but that land is to be loved and respected Is an extension of ethics. That land
yields a cultural harvest is a fact long known, but latterly often forgotten... .our bigger-and-better society
is now like a hypochondriac, so obsessed with Its own economic health as to have lost the capacity to
remain healthy."

Aldo Leopold, 1949
Foreword to A Sand County Almanac
XI. Introduction

The Ecological Society of America Committee on Sustainable Land Use has put together a set of

ecological principles and guidelines to hdp in land^ise decision making (Dale etaL, this vohune). Hie

practical application of these principles and the associated guidelines to planning efforts in real

landscapes will require the development and use of strategies and tools to translate diem into specific sets

of land-use practices (riparian buffers, floodplain and wetland restorations, etc.) and ways to place these

practices effectively on the landscape. In this chapter, we discuss the use of future scenarios coupled with

Geographic Information Systems (CIS) based evaluative models as a methodology for effective land-use

planning (cf.Steinitzetal. 1994, White et al. 1997, Hulse et al. in press). We demonstrate the application

of this method to explore alternative futures for two agricultural watersheds in (he U.S. CornbelL

X.2. Background and relevant concepts

Even before Leopold, naturalists and biologists of the 19* century realized that the pace cf agricultural

eJipngp was so rapid as to consume or fundamentally alter the natural vegetation cnmirqffii
Midwest. In the late 1800's, Thomas MacBride, Bohumil ShimA t txw*s Pommel *n4 gfofftr calted for

preservation of prairie and forest tracts to conserve the ratural heritage of Iowa However, conservation

plans written in the early 20* century did not translate into land set aside for preservation until the atid-
Preceding Page Blank

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1940's when, under the leadership of Ada Hayden, action was taken to preserve some remnants of the
native vegetation of Iowa (Roosa 1981).

In spite of more than a century of recognition of the importance of conservation, and decades of efforts to
develop sustainable agricultural practices, the pace of agricultural change and industrialization has
outstripped the pace of the adoption of conservation practices (Farrar 1981, Roosa 1981). Iowa has been
ranked 50* among the fifty United States in the amount of remaining intact natural habitat (Klopetek et
al. 1979). Tilling and cropping, removal of riparian forest, draining of wetlands, introductions of non-
native species, use of agrichemicals, and resulting pollution and soil erosion have contributed to declines
in water quality and loss of biodiversity in farmland (Crosson and Qstrov, 1990, Pimentel et al. 1991,
Freemark 1995, Schwartz 1995). Agricultural land use is the primary cause of surface water quality
impairment in the U.S. today (Puckett 1994, Alexander et al. 1996, Runge 1996). In 1995, the U.S. Office
of Technology Assessment (OTA 1995) designated tk. Corn Belt region as the top priority region for
action to improve surface water quality. Estimates of the sources of nutrient pollution to the Louisiana
Gulf Coast estuaries (Alexander et aL 1996) indicate that 70% of the total nitrogen delivered to the Gulf
originated above the confluence of the Ohio and Mississippi Rivers, with 39% of the total coming from
watersheds in the Upper and Central Mississippi basins. Regardless of regional source, the USGS has
estimated that about 90% of the nutrients entering the Gulf originate from non-point sources, primarily
agricultural runoff and atmospheric deposition.

X.2.1. Obstacles to the use of ecological principles in land>use decision making

The concept of using ecological principles to guide land use is not new, although it is still revolutionary.
On private lands, private economic returns to landowners nither than ecological principles tend to drive
land-use and management decisions. Private landowners often ignore the harm that their actions cause to
ecosystem processes, especially if those processes play out on a larger spatial or temporal scale. The costs

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of ecosystem damages may fall principally on others besides the landowner, both in current and in future
generations, thereby giving the landowner little direct incentive to prevent the damage from occurring.

The underlying motivation for using ecological principles to guide land use is rooted in a land-use ethic
that sees man as dependent on nature tor sustainable existence rather than its master (Leopold 1949). By
their nature, principles broad enough to be generally appUcable are abstract Land-use and management
decisions, however, are very specific. In order to be most effective, ecological principles must be applied
over spatial scales on the order of thousands of hectares or more, and time scales on the order of decades
and centuries. Decisions that determine whether or not an agricultural operation is profitable are made on
the spatial scale of a farm (hundreds of hectares) and often on a temporal scale of seasons or years.

Even when concrete goals and time frames have been established for improving ecosystem health, and
specific practices to achieve these goals are accepted as ecologically sound, economic barriers can be
difficult to overcome. Some ecologically sound practices may not pay for themselves in economic sense, at
least in the short to medium term (Walpole and Sinden 1997). Even if ecologically sound practices are
economically superior to current practices, sufficient benefits must accrue to landowners to convince them
to adopt the practices, or government regulation must make such practices mandatory. Often many
benefits of ecologically sound land-use decisions accrue outside the ownership of the land. Some means,
such as tax incentives or subsidy programs, has to be found to give landowners sufficient incentive to
choose ecologically sound practices. There is also a skepticism of adopting new methods when the tried
and true methods seem to work, at least from the landowners^ point of view. For example, research
results have demonstrated that certain conservation tillage practices are both eomomically and
MiyimnmtMitally «mmrf hit it hagialnm years hefare these practices have Ivyp «reqrt«d and adopted ty 8
significant fraction of fanners. Finally, the benefit of adopting eoologic^anirid practices often depends
on cooperation among multiple landowners. Ecologically meaningful units of land-use planning (such as
watersheds) often include a number of landowners, who by their participation or im-partitipation in the
process can enhance or negate the efforts of other landowners in their watershed. Getting multiple

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landowners to participate and gaining agreement on bow to snare the responsibilities and costs or benefits
often involves a difficult negotiation process.

In summaiy, for success in practical application of ecological principles in land-use decision making:

1. decision makers must understand the need nnrf share the goal
2. abstract principles must be translated into specific land-use decisions
3. responsibility for associated costs (which tend to occur up front and are specific to place)mustbe
assigned and acceptable to landowners and decision maters
4. benefits (which tend to be realized in the longer term and diffuse in space) must be understood and
shown to have enough value to outweigh immediate and specific costs
5. practices must be culturally acceptable (this includes respect for the rights of properly owners)

Until these conditions are met, it is unlikely that ecological principles will have substantial influence on
land-use decision making.

X.2.2. Future scenario approach: an effective strategy for land-use planning

Alternative future scenarios of landscape change can help decision makers visualize and evaluate
alternative choices in a way specific to time and place (Harms etal. 1993, Steinitz et al. 1994,
Schoonenboom 1995, Freemirk et al. 1996, Ahem 1999). Models which explore effects of different land-
use practices on species and key ecosystem processes can be effective tools for evaluation of alternative
scenarios (Dom'gUui and Huber 1991, Pnlliam and Danielson 1991, Dunning et al. 1995, Holt et aL 1995,
White etal. 1997). Equally important are assessments of economic impacts (eg. Williams et al. 1988,
Walpolc and Sinden 1997) and human perceptions of the alternative choices (Nassaner 1988). Finally,
methods must be developed for summarizing results of various evaluative tools in a coherent way (e.g.
Anselin et aL 1989, Heatbcote 1998).

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We present here a methodology for the use of future scenarios as a tool for guiding land-use decisions for

agricultural watersheds in the U.S. Corabelt. The goals of this project have been:

1. gf-nffrnt'ftT> nf designed alternative firtures thflf fvplnry p rfl"g? flf Infflffl" *n"d-
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The watersheds chosen for this study are two Iowa watersheds used in the Midwest Agrichemichal
Surface-subsurface Transport and Effects Research (MASTER) program. Both are within 120 km of
Ames, IA (Fig.1). Watershed area and some land-use characteristics are summarized in Table 1. Land-
use classes in Table 1 were summarized fiom land-cover data generated under MASTER (Fieemark and
Smith 1995). These land-cover data were digitized fiom 1:20,000 aerial photographs taken in 1990, and
ground-tmthed in 1993-1994.

Most of the land area in central Iowa lies within two landform regions, the Des Moines Lobe and the
Southern Iowa Drift Plain (Prior 1991). In order to represent the way the same land-use priorities might
be realized in different landform regions, alternative future scenarios were designed for two watersheds,
one (Walnut Creek, Story Co.) on the Des Moines Lobe, the other (Buck Creek, Poweshiek Co.) in the
Southern Iowa Drift Plain. These landform regions vary in their topographic relief and current land use.
Walnut Creek, like most of the Des Moines Lobe, is relatively flat with rich, productive soils. Its land
cover is dominated by com and soybean row crops (Fig. 2a). Buck Creek has a more rolling topography, a
highly branched stream network, and much more varied land cover (Table 1, Fig. 2b).

Historically, the Walnut Creek watershed, like most of Story County, was dominated by prairie, dotted
with prairie pothole wetlands, most of which have now been drained for row crops (Hewes 1951). Buck
Creek, located on an older glaciated surface had soils that were better drained Its hills and valleys,
particularly in the lower, southern end of the watershed, provided firebreaks that allowed the growth of
more extensive riparian forest Today, Buck Creek has soils more prone to erosion, hence more of the land
cover in this watershed is in pasture and Conservation Reserve Program (CRP) set asides. In addition,
there is more forest along riparian channels and in upland woods (Table 1, Fig. 2).
X.3.2. Scenario design
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Alternative future scenarios were designed by the landscape architecture team at the University of
Michigan, (Nassauer in prep.; ht^://www-personal.uinich.cdu/~nassauer/!ag_waterfhedf!/) in
consultation with disciplinary experts in the fields of agronomy, vertebrate ecology, plant ecology,
wetlands ecology, water quality, hydrology, agricultural policy, agricultural extension, and Geographic
Information Systems, including scientists from the region as well as collaborators on the project.

Scenario 1 (Figs. 3a, 4a) assumes that profitable agricultural production is the dominant objective of
landscape management, and that profit is perceived as short-term economic return. This scenario assumes
high demand for. Corn Belt grain crops by world markets, high use of iossil fuel, high use of chemical and
technological inputs, and public support for large-scale, industrial agriculture. Scenario 1 also assumes
that public trust in the quality of food produced by industrial agriculture is high, that the public perceives
the landscapes resulting from industrial agriculture to be environmentally acceptable, t*vt the fossil fuel
necessary to industrial agriculture remains economical or that alternative fuels emerge, and that die public
remains willing to support industrial agriculture (through research, direct payments to farmers, crop
insurance, etc.) at levels similar to the 199Q's. It assumes public incentives for conservation at a level that
encourages widespread adoption of the types of best management practices existing in 1994. Woodlands
disappear as more land is converted to cultivation. The Com Belt landscape has been depopulated by 50%
compared with 1994. Most farmers do not live on their farms through the winter months. Many
farmsteads have been demolished and groves cut down. Farm size has doubled, and field size has
increased up to 320 acres. Crops are corn and soybeans. Livestock are raised almost exclusively in
confinement feeding operations in a few counties of the state. Few people visit the rural landscape for
recreation.

Scenario 2 (Figs. 3b,4b) assumes that agricultural enterprises and practices have changed in response to
federal policy, which has enforced dear, measurable water quality performance standards for pollution of
surface and groundwater, on a farm by farm basis. Under this scenario, public emiionmental concerns are
assumed to focus on dean water. Public support for agriculture is targeted to practices that efficiently
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reduce soil erosion, reduce sediment delivery to streams, prevent the movement of excess nutrients to

streams, reduce the energy and flashiness of storm events, and improve aquatic habitat. Profits from worid

markets for beef and pork are prompting Com Belt interest in livestock enterprises. Forage crops and

extensive animal grazing (carefully managed to minimize impacts on riparian systems) have been widely

adopted as profitable enterprises that help to meet water quality performance standards on rolling or

credible land. Woodlands have been widely maintained for grazing. Both urban and rural citizens

appreciate the pastoral appearance of agricultural landscapes, where animals can be seen grazing on green

hills. Farm vacations and countryside second homes regularly bring urban people into rural areas. To

manage livestock operations and to respond to rural recreation demand, 50% more farmers live in Corn

Belt agricultural landscapes in 202S than under Scenario 1.

Scenario 3 (Figs. 3c, 4c) assumes that technology and agricultural practices have dramatically responded

to federal incentives to increase indigenous biodiversity across the nation. Public investment maintains

and restores native flora and fauna through a comprehensive system of reserves. It also supports profitable

agricultural production with new technologies that enhance biodiversity within agricultural production.

Public ecological perceptions and concerns drive federal investment in agriculture, which is targeted to

ecological results and long-term economic return. Under this scenario the world grain market is robust but

continues to produce a comfortable surplus. Public health perceptions and environmental concerns have

affected global dietary choices, and the global market for beef and pork has not dramatically increased as

predicted in 1998 (Worldwatch Institute 1998). Livestock enterprises have continued to trend toward

confinement feeding operations, which are constructed according to rigorous standards for sewage

treatment in a few counties. Federal land purchase programs have established at least one indigenous

ecosystem core reserve of at least 640 acres in many Iowa watersheds. Fedeial support for innovative,

biodiversity best management practices (e.g., perennial strip intercropping and agroforesuy) has been

targeted to landscapes that connect and buffer the new resenrc and riparian conidors. The substantial

public investment in core reserves and corridors invites public enjoyment of the rural 'nmftcapr Trail

systems connect the corridor system and the reserves. While farm size increases as in Scenario I, and the
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number of farms decreases to about 50% of the number present in 1994, nearly all of the farmsteads

present in 1994 remain inhabited in 2025. Many non-farmers who enjoy the beauty of Wodiversfty in the

rural landscape live on farmsteads no longer occupied by farmers.
Once designed, the alternative futures were digitized into representations of future land cover in a CIS.

The GIS provides spatially-explicit input data to a variety of models that can be used to evaluate the
generated from the Iowa Soil Properties and Interpretations Database (ISPAID), based on characteristics

of soils formed under prairie and forest vegetation (http://www.ia.nrcs. usda.gov/soilsAcss_data.html), and

wetland types associated with hydric soils (Galatowitsch and van der Valk 1994). Historic and current

land cover for each watershed thus provide landscapes for relative comparison with the alternative futures.

X.3.3. Scenario evaluation

A suite of modeling approaches were then used to evaluate and contrast the response of water quality,

economic profitability, and plant and animal biodiversity in these two agricultural watersheds to changes

in land use and management eiieh as varying width of riparian hnflferet efiteHfchment ^f l^rgp patches Of

restored native habitat in reserves, and changes in the agricultural matrix itself (field size, cropping

practices, interpolation within fields of perennial cover such as grass waterways, filter strips, field skips

etc.).

The use of several different water quality models to evaluate the scenarios for water quality response was

explored, and SWAT (Soil and Water Assessment Tool) (Arnold et al. 1997) was chosen as best suited to

these watersheds and the available data. Calibration of the model to the study watersheds has been an

important outcome of this effort (Vache et al. in prep.) in addition to the ranking of the scenarios.
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The economic model EPIC (Erosion Productivity Index Calculator) (Williams 1988) is being used to
simulate yields and economic returns from agricultural production. Ecological benefits can then be related
to their economic cost to the producer, helping policymakers understand, for example, the relative
magnitude of incentives or subsidies that would be required to entice landowners to adopt a given set of
practices. In addition, spatial representations of the alternative futures along with computer-generated
images of the way the scenarios might look in simulations of the landscape have been used in farmer
interviews intended to discern cultural acceptability of specific agricultural practices (Nassaoer in pttp.).

For modeling risk to biodiversity, our approach was to combine an heuristic model (White etal. 1997)
that responds primarily to change in habitat area for species as a "coarse-filter", with Spatially-explicit
Population Models (SEPMs)as "fine-filter" approaches to assess the impact of changes in land use and
management on species of interest (Clark et al. in prep; Rustigian 1999).

For some species, spatial patterns of habitat fragmentation may be very important in determining
persistence of populations; however, some results suggest that degree of fragmentation can be a much
smaller effect than the amount of habitat itself (Fahrig 1997, Tizcinski et al. 1999). Multiple modeling
approaches can help to elucidate these issues and provide several perspectives on landscape effects on
biodiversity. The combination of simple habitat loss models for a wide range of species (White et al.
1997) with spatially-explicit demographic modeling of species selected for representativeness in fife
history traits or other factors (Dunning et al. 1995) provides a broad first-order analysis of effects, with
details on how these effects may be modified for certain classes of species. In addition, where habitat loss
itself is the primary determinant of species declines, simple, empirically-based models can be used for
rapid evaluation of multiple alternatives and in exploration of the sensitivity of various taxa or groups of
taxa to elements of landscape change.
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Multi-species models and detailed landscape structure analysis offer a promising method for examining
ecological community processes. Simulations provide a systematic, quantitative approach to assessing
factors affecting communities and populations within those communities. With spatially-explicit models,
comparisons can be made between effects of landscape and species interactions, both of which may
influence community diversity and dynamics (Palmer 1992, Losey and Denno 1998, Korpundki and
Norrdahl 1998). When comparing landscapes with different amounts of habitat or physiognomy, it is
important to determine hour efficiently habitat i«t mcplnita^ in afrJMpn ft> ^Hfetgnc
densities. One metric providing a normalized measure of the efficiency of habitat exploitation is relative
density (population density in a patch in proportion to patch carrying capacity). Relative densities can be
compared for different species as they respond to a given landscape, for a single species in response to
different landscapes, or for species in a community or alone. Clark etal. (in prep.) compared relative
densities predicted from spatially-explicit single and multi-species models of mammals applied to the
Buck Creek and Walnut Creek watersheds to assess the relative importance of habitat loss and species
interactions. Their results suggest mat for species with relative densities unaffected in different
landscapes, populations change linearly with the abundance of suitable habitat, similar to their finding
that diversity increases nearly linearly with non-crop, grassland habitat.
The comparison of spatially-explicit alternative scenarios with models is a first step in quantifying the
economic and ecological costs of continuing current practices as well as the benefits of some potential
changes. In many cases, models can onry approximate the watershed response to changes in land use,
ranking the futures with respect to their efiectrvtness in achieving the desu^ objectives. However,
•
ranking of ah^niatrves is omy one function of models (Starfidd 1997). An equally important role of
modeling is to explore the state of our current understanding of existing procesies, locate criticd areas
where data are needed to improve assumptions and effixtively parameterize nioojels, and focus additioual
research efforts to help fill important gaps in our understanding. In addition, as wnlilandsise plans that
are implemented and then evaluated (Ahem 1999), the application of evaluative models to alternative
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futures can facilitate further discussion, collaboration and knowledge exchange among landscape
planners, policy makers, and ecologists. This approach provides a means to evaluate a broad range of
innovative alternatives (which might be costly to implement in experimental studies), to winnow out those
that are clearly unfeasible or undesirable, and focus important experimental research on options with the
greatest promise.

X.4. Application of ESA principles and guidelines in the context of this project

X.4.1. Principles

In many ways, the principles outlined by the ESA Committee on Land Use are applicable to this project,
although both efforts evolved independent!}. The use of alternative future scenarios makes land-use
choices both spatially and temporally specific (principles 1 and 3). We use a "twenty-five years out"
perspective, and contrast the landscape level effects of alternative future choices designed to restore native
biodiversity and improve water quality with those resulting from perpetuation of current trends. Effects of
landscape change from the historical past to the present can also be effectively illustrated, using historic
landscapes as the basis for comparison. Thus, designed alternative future landscapes can be contrasted
with three "standard" landscapes for the same watersheds; an historic landscape, the current landscape,
and the landscape that may result from perpetuation of current trends.

Because they are based on real watersheds, future scenarios and the tools used to evaluate them consider
the influences of and impacts on the species assemblages chaia«rteiistic of the region (principle 2). Incur
study, for example, the goal given highest priority in designed future Scenarios was restoration of native
biodiversity. We are employing several modeling approaches based on plant and animal species of the
region and their response to habitat loss or restoration (Freemark et al. in prep, Santelmannetal. in prep.)
14
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as well as to their population dynamics in combination with other species in the watershed (Clark et al. in
prep., Green and Galatowitsch in prep., Rustigian 1999, Rustigian et al. in prep..)

In the future scenarios, we specify the intense disturbance regimes associated with agricultural practices,
as well as practices such as prescribed burning (intended to. emulate historic natural disturbance regimes)
to be used in management of nature reserves (Nassauer et al. in prep.). These disturbances are
incorporated into the models used to evaluate the futures (principle 4).

Landscape characteristics (principle 5) such as the size, shape, and relationships among habitat patches
were important considerations in the choice of study watersheds, the design of the future scenarios, and in
the models used to evaluate them. For example, increases in field size and the resulting coarse-grained
agricultural matrix associated with current trends for industrialization of agriculture (represented by
Scenario 1, the perpetuation of current trends) are contrasted with smaller field sizes and more diverse
types of land cover in the designed futures (Scenarios 2 and 3). In addition, the scenarios were designed to
allow comparison of the effects of riparian corridors of varying widths, and the creation of huge reserves
for the restoration of native biodiversity (Nassauer et al. in prep.).

X.4.2. Guidelines

Several examples of how the guidelines suggested by Dale et al. (this volume) might be applied to real
landscapes are illustrated by the designed scenarios. The coupling of future scenarios with CIS-based
evaluative models allows both the examination of the impacts of land-use decisions in a spatial context
and exploration of the effects of long term change (gmctelines 1 and 2). The scope of the stud^ determines
the regional context and time frame in which these impacts can be evaluated In Scenario 3, the use of
native plants along roadsides, in farmsteads, and in strip intercropping, as well as the establishment of
biodiversity reserves, represent efforts to restore regionally rare landscape dements and associated species
(guideline 3). The adoption of innovative agricultural practices such as strip intercropping, the use of
IS
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filter strips, and specifications that highly credible land and land adjacent to streams be in perennial crops
or land cover (Scenarios 2 and 3) are elements designed to reduce soil erosion and loss of organic carbon
(i.e., guideline 4, avoid land uses that deplete natural resources). The establishment of biodiversity
reserves connected to a wide riparian network in Scenario 3 embodies the guideline for large contiguous
or connected areas of critical habitat. Finally, in each of the designs, CIS data bases on soils and current
land cover were used to guide allocation of future land-use and management practices compatible with the
natural potential of the area (guideline 8). For example, in Scenario 3, wetland restorations were located
in areas with hydric soils suitable for prairie pothole wetland restorations, additional areas of forest for
reserves were added adjacent to existing forested land cover.

X.5. ESA guidelines: implications and additions

X.5.1. Implications of existing guidelines

The principles and guidelines developed by the ESA Committee on Land Use are an essential starting
point for the incorporation of ecological thought into land-use planning. Not only have they articulated a
set of principles and defined guidelines that derive from those principles, they have summarized the
voluminous, controversial, and sometimes contradictory ecological literature in the context of these
principles (Dale et al. this volume). Their efforts provide a foundation for ecologists to work from and
build on in collaboration with others working in the areas of land-use planning. To that end, we suggest
three additional principles and accompanying guidelines: (1) consideration of hind-use impacts on
ecosystem processes (2) consideration of the human dimension of effective planning, and (3)
understanding and communication of uncxrtamtym injects of land-use practice and associated risks.

X.5.2. Ecosystem processes
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Principle: substantial land-use impacts on some systems, particularly lakes, streams, riparian and coastal
marine systems, often originate outside the boundaries of that system.

Guideline: consider effects of land use on ecosystem processes both within and across ecosystem
boundaries

A critical ecological principle incorporated into our research is the importance of understanding effects of
land use and management on ecosystem processes, such as exports of nutrients and sediment from the
watershed, or alterations of the hydrologic regime. In agricultural regions, processes such as soil erosion,
drainage of wetlands, channeling of streams and rivers and accompanying hydrologic changes, and
nutrient and sediment exports from the system have long been recognized as problems. Human alteration
of the nitrogen cycle and non-point source pollution of surface waters with phosphorus and nitrogen are
having severe, global environmental impacts (Vitousek et al. 1997). Land-use and management practices
that reduce nutrient exports must be incorporated into land-use planning for agricultural regions in
particular if we are to address some of the most serious environmental problems that stem from
agricultural land use.

X.S.2.1 Defining cycles and processes on which land use has greatest impact

In ovder to incorporate considerations of ecosystem pnx«sses into land-use planning, we must first
determine which processes •*** cycles (hydrologic, carbon, nitrogen, phosphorus etc.) in the planning
entity are most affected by land-use and management practice. Tte nwst critical impacts of a grven
practice (for example, cropping and tillage) may differ from one watershed or region to another. Our two
study watenhedi differ in the degree to which sediment and nutrients are the primary water quality
problem. Buck Creek, with its rolling topography, highly erodibte soils, and extensive livestock
production, has p*«*q«ifai problems with fffdinwtt, which during major storm events can be measured in
grams per liter rather than the usual milligrams per liter for strearns (Eilers and Vache, unpublished data).
17
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Although nitrate levels in Buck Creek are higher than might be desired, they tend to be lower than the

levels in Walnut Creek, where nitrate-nitrogen concentrations average near the drinking water standard of

10 mg L"', with peak concentrations higher than the standard (USDA ARS, unpublished data).

Components of the designed scenarios such as riparian buffers, wetland restorations filter strips, and some

of the alternative cropping practices were intended to explore alternatives that are currently part of federal

programs (CRP, CREP, WRP, EQIP) to control soil erosion and improve water quality, and compare their

effectiveness to landscapes in which innovative agricultural practices and permanent reserves are used to

achieve similar purposes.

Proposed land-use or management practices must target specific environmental goals. In land-use

planning, there are multiple ways of addressing the same broad goal in alternative future scenarios. For

example, in the Netherlands, where conservation and restoration of habitat for native species was a

primary goal of landscape planning efforts, a number of configurations of habitat have been designed,

each benefiting different sets of species with different life histories (cf. Harms et al. 1993). Simu*rly, if

improvement in surface water quality is a desired goal, there are multiple ways to achieve improvements

on agricultural land by changing land-use or management practices. Different practices will be most

effective for different water quality problems. If soil and stream bank erosion which deliver sediment to

streams are the primary water quality problem in a watershed, vegetated filter strip? and riparian buffers

may be extremely effective solutions (Daniels and Gilliam 1996). If dissolved nutrients that reach the

stream primarily in flow from tile drains are the primary problem, riparias buffers stay be a smaller part

of the solution.

X.5.2.2. Contrasting approaches: exploring effects of specific practices or targeting specific

l goals?
18
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One major decision in the generation of alternative scenarios is between the choice to explore the
implications of implementation of a particular set of practices, eg. "how much improvement in water
quality could we achieve by establishing riparian buffers along the entire stream network in this
watershed?" compared to an approach which attempts to explore various ways to meet an environmental
standard, eg." we need to reduce nitrate export from this watershed to (some target level); what land-use
or management changes could help achieve this? how far towards the target goal might each take us?".

In the first case, all that is needed is an understanding of the sets of practices that are likely to be favored
by policy and a means to locate these effectively on the landscape (knowledge of soils, topography,
geomorphology, existing land cover). Whether the estimated improvements in water quality are minimal
or substantial, one will be able to address the research question with respect to the effects of
implementation of a given policy.

In the second case, at the very outset of scenario design, thought must be given to "mass balance"
considerations, to the magnitude of the measures needed to achieve desired results. If, for example, the
goal of the prospective land-use and management practices is 75% reduction in nutrient export from the
watershed, and filtering of runoff through restored wetlands is suggested as a land-use mechanism to
achieve this goal, the area! extent of such wetlands must be substantial to achieve such a substantial
reduction. In addition, the type of wetland restored must be appropriate to the desired function. Small
depression wetlands in headwater areas may have little opportunity to agamilate nutrients because they
tend to have a small catchment areas and low flows. Riverine wetlands, which are linked more extensively
with uplands and riparian systems, can have greater capacity for altering water quality (Brinson 1988).
Detention ponds at outlets to tile drains in the watershed may be effective for nutrient removal under tow
flow conditions, but may be overwhelmed by storm events or spring snowmehX Single storms in a given
year can be responsible for most of the sediment and nutrient export from fields adjacent to riparian areas
(Daniels and Gilliam 1996), thus understanding dynamics of nutrient export and the hydrology of the
system is important to effective restoration design. Much more watershed-specific information is needed
19
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at the outset when the research objective of the scenario design process is achievement of a targeted goal,

and the process will likely require several iterations to identify cost-effective alternatives that achieve the

desired goals. Choice of modeling approaches used will also be critical; tradeoffs may have to be made

between precision and flexibility of the model(s) used if there is a need to explore multiple landscape-

level solutions. If the research objective is to explore alternative ways to achieve a targeted goal, at least

some of the alternatives must reach the target; this may not happen in the initial designs.
X.5.3. Human dimension

Principle: To be sustained, land uses must be recognized as valuable by landowners and the larger

community (Nassauer 1997).

Guideline: Implement land-use and management practices compatible with human economic and cultural

practices and values.

Designing new land-use patterns that recognizably fulfill human aspirations is as important to

sustainability as is designing patterns that are compatible with the natural potential of the area. Gaining

acceptance for ecologically sound land use and management practices requires that local landowners and

decision makers find these practices attractive, both financially and otherwise. Innovative practices and

landscape patterns that people do not like or which do not fulfill economic needs are not sustainable over

time (Nassauer 1997). Landscape design, planning, economics, and social science can help policy makers

anticipate human perception* and behavior in response to new land-use patterns. Ecology can suggest the

ecological purposes for innovative landscape patterns, but it alone cannot tell us what the new patterns

should be.
20
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We acted on this principle in designing three alternative scenarios for Corn Belt agricultural watersheds

in 2025. The landscape architects drew on the expert knowledge of colleagues in several disciplines, and

drew on environmental design research to shape innovative landscape patterns that local people would be

likely to find acceptable. Each scenario was actively informed by consultation with colleagues in ecology

and hydrology as well as agronomy and economics. The scenarios were designed to be recognizable and

plausible as agricultural landscapes that would be economically viable under the assumptions of each

scenario and would be desirable as a place to live and to farm. Each scenario, then, was an hypothesis

about cultural acceptability as well as a response to expert knowledge about how the landscape could

function - agronomically, hydrologically, and ecologically.

These hypotheses were formally tested in on-farm interviews with Iowa fanners (Nassauer and Cony, in

prep.). The real test of cultural acceptability will be in individual fanners' responses to any new policy,

market, or technology that would intersect with existing cultural values and practices to meet the

assumptions of any of the scenarios.
X.5.4 Understanding i"*oe|tainty

Principle: Future predictions always carry some degree of uncertainty

Guideline: The magnitude of uncertainty associated with potential effects of land-use alternatives should

be explored and expressed in communication with decision makers, and used to focus additional research.

Another important issue eootogists and modelers must deal with is the uncertainty inherent in n*~Hiiig

However, ecotogists and modelers often do a poor job of communicating levels of uncertainty to decision

an
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Sensitivity analysis of models used to evaluate future scenarios can focus additional research by

identifying input parameters to which the model is sensitive. Those parameters for which there is the

greatest amount of uncertainty at present, for which reductions in uncertainty would most improve the

accuracy of model predictions should become the targets of additional research.

One of the most intractable problems in the use of future scenarios is that there is an inverse relationship

between the degree of innovation in a land-use practice or scenario and our ability to model it accurately.

The innovative land-use practices which may be of the greatest interest in the long run are also the ones

whose effects on ecological endpoints are most difficult to estimate, particularly at the spatial scale of

watersheds five or ten thousand hectares in area instead of fields on farms or agricultural experiment

stations a few hundred hectares in area. Models and sensitivity analyses can be used to explore the

potential impacts of innovations in small watersheds such as Buck Creek or Walnut Creek, but the results

will always have a high level of uncertainty associated with them until they have been tried at the spatial

scale of such watersheds. Extrapolating results of experiments carried out on 100-hectare plots to

watersheds 5,000 to 10,000 hectares in area or more ignores a hierarchy of processes and interactions that

can qualitatively alter the expected outcome. The sustainable production of agricultural commodities,

preservation of biodiversity, clean water and healthy aquatic systems in the future are all critically

important components of agricultural ecosystem health. Great risks may be posed to both the agricultural

economy and agricultural ecosystems if model predictions are not accurate. Thus, long-term ecological

research on the application of innovative agricultural practices at multiple spatial scales (ie., field, farm,

small (5-10,000 ha) watershed, as well as larger hydrologic units) should be a funding priority.

The research described here is a first step on the road to incorporating ecological principles and

ecologically sound practices into land use and management in the U.S. Cora Belt The designation of

long-term agroecological research sites at least the size of these watersheds would be an important step in

the advancement of ecological research and the adoption of ecological principles to guide land use in

agricultural regions. Long-term ecological research in agricultural watersheds will be important not only
22
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for model validation but as demonstrations that real watersheds can have working farms and substantial

environmental results (improved water quality and stream health, enhanced biodiversity, abundance of

wildlife, and aesthetic appeal). Such watersheds will be the strongest advocates we could have to induce

change.

Our next steps (Clark et al. in prep., Coiner et al. in prep, Freemark et al in prep., Nassauer et al. in prep.,

Santelmann et al. in prep., Vache et al. in prep.) will be to rank the future scenarios with respect to their

effectiveness in achieving the goals of the designs, explore ecosystem response to specific land-use

practices using spatial models, describe the outcomes of the modeling efforts, and integrate the multiple

modeled endpoints for assessment of the alternatives. We hope the results will inspire and guide further

watershed-level research in agricultural ecosystems.
X.6. Conclusions

More than 52% (398 million ha) of the land area in the continental U.S. is in farmland (USDA1992).

Ecological principles and guidelines must be incorporated into land-use and management decisions on

agricultural land or agricultural ecosystems and the aquatic systems to which they are linked will be

neither healthy nor sustainable. Central Iowa, in the heart of the U.S. Com Belt, is a highly productive

agricultural region dominated by private land ownership and agricultural land use. Changes in land use

must be acceptable to private landowners and economically feasible. Understanding the human dimension

of changes in agricultural land use and adoption of conservation practices will be a critical step in the

development of ecologically-healthy agricultural landscapes. Partnerships between those who have

developed and studied innovative agricultural practices and those who must use them on their farms will

be important Economic analyses can help policy makers understand the magnitude and extent of the

incentives or agricultural subsidies that might be required to make a given practice economically viable in

the economic context of agriculture today. If the costs of implementing ecologically sound practices
23
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cannot be recouped by landowners within a time frame they find acceptable, then agricultural policy
makers will need to develop alternatives for financing these practices.

The ecological impacts of innovative agricultural practices need to be studied not only at the field scale
(hundreds of hectares) but also at the small watershed scale (thousands of hectares) and above in order to
improve our understanding of thrir effectiveness at the scale on which they might someday be
implemented Research on biogeau* mical processes that influence biogeochemical cycles in agricultural
watersheds must be a component of such whole-watershed research. In addition, responses of plant and
animal species will be among the most sensitive indicators of ecological response to changing land use,
and are affected by processes at multiple spatial scales (Pratt and Cairns 1992). Responses of species to
interspecific interactions may be as important as their responses to changes in land use.

Success in the application of ecologically-sound land-use decisions will require strong local leadership
and broad, community-based planning. The U.S. EPA Office of Water and Watersheds wsb site, "The Top
Ten Tips for Watershed Practitioners" (http://www.epa.gov/owow/) presents case studies which illustrate
applications of watershed-level planning with both successes and failures. Research projects such as the
one described here can provide inspiration for local communities to envision more innovative practices
than might otherwise be the case, as well as providing information and evaluative tools for community-
based planning efforts.

Partnerships among ecologists, planners and local communities in application of ecological principles and
guidelines to land use and management will require substantial effort, and challenge all of us to listen and
learn from other perspectives. However, only through such efforts will we be able to realize the vision for
the land articulated by Leopold and others who have spoken out for ecologically healthy and sustainable
land use
24
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Acknowledgements

We acknowledge support from the U.S. EPA/NSF Partnership for Environmental Research STAR grants

program, grant number R825335-01. We thank Dr. Gerald Hatfield of the USDA ARS Tilth Laboratory

for generously sharing with us water quality data collected on the Walnut Creek, Story County watershed.

We are grateful to the many individuals at Iowa State University, University of Iowa, University of

Minnesota and their associated agricultural extension services, as well as the USDA NRCS and Iowa

Geological Survey, who contributed their time and knowledge to this project, and whose work provides

the foundation for the development of ecologically healthy agricultural ecosystems. Thanks to P.J.

Wigington, George King, and three anonymous reviewers whose review and comments on the manuscript

improved it. Thanks also to John Bolte, Court Smith, and Jennifer Gilden for informative discussions on

application of ecological goals in land-use planning.
25
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Figure Captions

Figure 1. Study watersheds in Iowa. Counties included in our delineation of the Central Iowa region are

outlined in bold Shaded area shows the extent of the Des Moines Lobe Landform Region, unshaded areas

are part of the Southern Iowa Drift Plain (Prior 1991).

Figure 2. Current land cover in study watersheds (a) Walnut Creek, Story and Boone Counties and (b)

Buck Creek, Poweshiek County. Land cover data interpreted from aerial photographs 1:24,000 and

ground-truthed under the MASTER research program (Freemark and Smith 1995). (Note: although strip

intercropping is not found in the current land cover in these watersheds, it does occur in the future

scenarios (Figs. 3 and 4) which share this legend).

Figure 3. Designed alternative scenarios for Walnut Creek watershed (a) Scenario 1 (b) Scenario 2 and

perennial cover for Scenario 1; the increased ;unount of land in perennial cover (pasture and forage crops)

as well as wider riparian buffers and detention pond wetiands in Scenario 2, and the biodiversity reserves,

wide riparian buffers and extensive prairie, forest and wetland restorations in Scenario 3. Features of

Scenarios 2 and 3 not visible in these maps are the use of crop rotations that include alfalfa and oats in

Scenario 2, and the incorporation of organic crops and strip intercropping that includes a strip of native

perennials as an agricultural innovation in many fields for Scenario 3 ( see descriptions in Nassauer et al.

(in prep.) for more detail on the future scenario designs).

Figure 4. Designed alternative scenarios for Buck Creek watershed (a) Scenario 1 (b) Scenario 2 and

for Figure 3) but applied in a different landscape context.
33
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Table 1. Characteristics of study watersheds. Land-use data are summarized from

Freemark and Smith (1995) for 1994 land cover of the study watersheds. Physiographic

regions are described in Prior (1991).
Walnut Creek
Story/ Boone Co.
Buck Creek
Poweshiek Co.
Physiographic Region Des Moines Lobe Southern Iowa Drift PI
Total land area (ha)
Percent of land area in following land uses:
Row crops
Pasture/grassland
CRP
Woodland/savanna
Alfalfa/hay
other
5130

83
4
0
5
2
6
8790

45
20
16
9
4
6
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Icwa
-------

(b)
.3?
miles
Legend
?•'. How Crops

Slnp Int - oppiiKj

Perennial Herbaceous C

Woodlond'Woody Cove*

Water/Wetland
0 , 1
miles
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(b)
Legend
Row Crops
Strip Intercropping
Perennial Herbaceous Cover
Woodland/Woody Cover
Water/Wetland
Urban/Residential/Roads
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'57
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3"?
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(a)
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u
-------