The Willamette River is the 13th largest river in the United States, and its 29,727 square kilometer basin supports a mosaic of agricultural, timber, and recreational resources as well as several growing urban centers and their water supplies. The Willamette River Basin (WRB) has a Mediterranean climate with dry summers and wet winters. The river drains the Coast Range on the west side of the basin, the Willamette Valley, and the Cascade Range to the east. The conifer forests that dominate the Coast Range and Cascade Range are among the most productive forests globally. They are economically and ecologically important for providing timber products, habitat for a diverse array of wildlife species, dependable supplies of clean water, and recreational opportunities. Rich alluvial soils in the broad valley bottom support a variety of high value agricultural crops such as grass seed, vegetables, fruits, nuts, and wine grapes. A small but increasing share of many of these crops are grown using organic farming methods. The Willamette River network supports a wide variety of native and exotic fish species. Several species of salmon native to the Pacific Northwest are listed under the Endangered Species Act.1 These cold-water species are particularly sensitive to human activities—for example, stream channelization and removal of streamside trees—that can increase water temperatures above biological limits for survival. Efforts to mitigate excessive stream temperatures have resulted in the development of an ecosystem services marketplace for water cooling credits.2 This marketplace provides payment to landowners and other stakeholders for restoration actions that reduce stream temperatures, for example, through restoration of riparian forests and wetlands that provide shade and inflow of cooling groundwater. Such actions also provide additional services such as improved aquatic habitat, flood control, and carbon sequestration. Similar marketplaces for greenhouse gas offsets, wetland mitigation, and other ecosystem services are also being developed.3

In the next 30 years, the human population in and around the WRB is anticipated to grow from 2.7 million to almost 4 million. The increasing population is a major, basin-wide driver that will increasingly limit the delivery of ecosystem services. The Willamette River Basin provides an excellent case study because it features diverse and highly valued resources providing numerous ecosystem services. These services are certain to be impacted by population growth, land use and land cover change, climate change, and other stressors. The Willamette River Basin provides services that are vital to society’s well-being, yet these services are limited and often taken for granted as being free. The historical pattern of resource use in the WRB has often been one of boom and bust, with unsustainable management practices leading to severe downturns in major industries, such as the once thriving salmon fishery and forest products industries. Through our research, we are addressing the question, can methodologies be developed to quantify and value the WRB’s ecosystem services, so this “natural capital” can be better accounted for in decisions that affect the supply of the goods and services upon which human well-being depends?

Ecosystem Services

Society is in the early stages of developing processes and methodologies to quantify and value the services provided by ecosystems. While today’s technology and knowledge can help reduce the impacts humans have on ecosystems, they are unlikely to be deployed fully until ecosystem services cease to be perceived as free and limitless and their full value is taken into account. We may know the technological cost of providing clean drinking water and clean air, but we do not really know the value of lost or existing ecosystem services, which may perform the same functions more economically. Without this understanding, we can neither realistically determine the cost of pollution control regulations nor accurately calculate the economic benefits of ecosystem services.


Connie Burdick
Major land use and land cover categories in the Willamette River Basin.

In response to this critical need, the Environmental Protection Agency (EPA) initiated the Ecosystem Services Research Program (ESRP) in 2005 to conduct innovative ecological research that provides the information and methods needed by community planners, land managers, and other decision makers to (1) explore trade-offs in ecosystem goods and services resulting from alternative choices, and (2) quantify community and landscape sustainability trajectories to balance environmental, economic, and social criteria over timescales relevant to immediate needs and long-term (decades to centuries) planning goals.4 Researchers are initially focusing on five geographic locations across the United States: the Willamette Basin, Tampa Bay, the coastal Carolinas, the Midwest, and the Southwest. These locations include a variety of ecosystem types, such as wetlands, agricultural lands, forests, and coral reefs, and span a variety of spatial scales and issues of concern.4

A central theme of these ESRP “place-based” studies is that ecosystem services are tightly linked, or “bundled,” such that management decisions targeted for one service may have far-reaching positive or negative impacts on other services. Previously, under EPA’s longstanding risk assessment paradigm, models typically were used to assess single or narrow sets of environmental endpoints.5,6 For example, risk assessments concerning water or air quality traditionally have been treated as isolated issues by distinct program offices within EPA. Thus, EPA’s Office of Air and Radiation and Office of Water are responsible for establishing independent criteria for regulating levels of mercury and other toxins in the nation’s air and water to protect human health and the environment. Given the historical division of regulatory authorities and supporting research, it has often been difficult to predict how proposed standards for airborne emissions of a toxic substance might impact drinking water supplies or aquatic organisms many miles downstream from a particular airshed. The EPA established the ESRP to help formulate methods and models that consider broader sets of endpoints. Under this new paradigm, the ESRP is developing much more comprehensive assessments that quantify how multiple ecosystem services interact and respond in concert to environmental changes. A major goal is to assess how alternative climate and land use scenarios will simultaneously affect trade-offs in food and fiber production, regulation of water quality and quantity, reduction of greenhouse gases, and other services. Essential to this goal are highly integrated models that can be used to define policy and management strategies for entire ecosystems, not simply individual components of the ecosystem.7

Studying Ecosystem Services in the Willamette River Basin

We established the Willamette Ecosystem Services Project (WESP) in the Willamette River Basin in western Oregon to address the ESRP’s local and national decision support objectives.8 Our research includes monitoring, modeling and mapping, and analyzing how alternative-future scenarios impact ecosystem services and human health. We are developing analysis tools that support community decision making oriented around the provision of ecosystem services and that allow end users to explore different policies for land, water, and ecosystem management and to consider the resulting trade-offs in the production of ecosystem services. This effort is producing tools to help enable decisions that better account for the full value of ecosystem services in their present condition and as they may be altered in the future. We are developing a broadly applicable approach and the decision support tools for quantifying a variety of ecosystem services based on relevant local information, in this case, for Oregon’s Willamette River Basin (WRB). Our overall goal is to conduct new research to characterize ecosystem services and to present this information in decision-relevant contexts.


Eric Vance/EPA
Controlled environment chambers at the EPA lab in Corvallis, Oregon, are used to study the effects of air pollutants and other stressors on native plant species. A variety of experimental data is needed to calibrate and verify the simulation models used to inform environmental decision making.

The research we are conducting in the WRB is yielding answers to questions that need to be addressed nationwide, such as how to best assess, protect, and enhance ecosystem services. This necessarily requires a number of important considerations: engagement of clients and stakeholders to understand and incorporate their needs and decision processes; access to or development of common datasets necessary to inform ecosystem services assessments; access to or development of state of the art models capturing important drivers of ecosystem services dynamics; and development of robust, flexible, and extensible decision tools and frameworks allowing the exploration of impacts of alternative management strategies on the production of ecosystem services bundles. We focus on six key services of interest to EPA in the WRB that address the role of ecosystems in regulating stream water quality and quantity, biological sources of greenhouse gases, wildlife populations and habitat, fish populations and habitat, air quality, and production of food and fiber (e.g., lumber, pulpwood, and biofuels).

We have also identified a list of stressors or drivers in the WRB that are known to alter the provision of these services, such as climate change and land use and land cover management (land cover refers to vegetation type, for example, forests, agricultural crops, grasslands, etc.). Climate change is widely recognized as a critical global environmental problem. Rising temperatures, altered precipitation amounts and patterns, changes in accumulations and melting rates of mountain snowpack, and species range shifts all are resulting from climate change, and all have the potential to influence ecosystem services within the WRB. Land use and land cover management and modification significantly influence the extent to which ecosystems can provide the services on which humans depend. Population growth and economics remain the most significant drivers of land use and land cover change within the WRB.

An Alternative-Futures/Ecosystem Services Decision Platform: Envision

Central to WESP’s goals is the development of a robust, decision-support platform for projecting future changes in ecosystem services in response to alternative decision scenarios. The Envision computing platform provides significant capabilities compared to other existing tools for assessing ecosystem services: (1) it is spatially explicit, supporting spatial models and tools for mapping dynamic changes in landscape characteristics; (2) it is temporally explicit, supporting assessments of current landscapes and trajectories of change; (3) it is a framework, supporting inclusion of a wide variety of models, decision tools, and datasets within an adaptable software architecture that allows rapid customization of applications to address specific needs and geographies; (4) it can be applied at any scale of analysis, from community-centric applications to regional assessments involving multiple communities and ecosystem types; (5) it provides direct support for capturing policies and management alternatives; and (6) it provides tools for decision support, including trade-off analyses, which compare results from alternative-future scenarios.9

Multi-agent models such as Envision simulate the actions of various “agents”—that is, individual persons, such as landowners and other citizens, or organizations and institutions, such as governments and businesses. Such models have emerged recently as a useful means for representing human behavior and decision making within complex environmental and socioeconomic settings.


John Bolte

John Bolte is professor and head of the biological and ecological engineering department at Oregon State University. He has been active in ecosystem analysis, modeling, and the development of alternative-futures...


Robert McKane

Robert McKane is a research ecologist at the U.S. Environmental Protection Agency in Corvallis, Oregon. He has 25 years of experience in the use of simulation models for analyzing the effects of land use...


Donald Phillips

Donald Phillips is a research biologist at the U.S. Environmental Protection Agency in Corvallis, Oregon. Over 23 years at the EPA, his research has included a variety of studies of effects of climate...


Nathan Schumaker

Nathan Schumaker is a research ecologist at the U.S. Environmental Protection Agency in Corvallis, Oregon. He specializes in simulation model development and applications, landscape ecology, and conservation...


Denis White

Denis White is a retired geographer formerly with the U.S. Environmental Protection Agency in Corvallis, Oregon, and Harvard University. He specializes in the use of geographical information systems to...


Allen Brookes

Allen Brookes is a computer scientist at the U.S. Environmental Protection Agency in Corvallis, Oregon. He specializes in the development of ecological simulation models and their integration within decision-support...


David Olszyk

David Olszyk is a research ecologist at the U.S. Environmental Protection Agency in Corvallis, Oregon. His research has included a variety of studies of the ecophysiological effects of environmental stresses...

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