National Academies Press: OpenBook

Valuing Ecosystem Services: Toward Better Environmental Decision-Making (2005)

Chapter: 3 Aquatic and Related Terrestrial Ecosystems

« Previous: 2 The Meaning of Value and Use of Economic Valuation in the Environmental Policy Decision-Making Process
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

3
Aquatic and Related Terrestrial Ecosystems

INTRODUCTION

An ecosystem is generally accepted to be an interacting system of biota and its associated physical environment. Ecologists tend to think of these systems as identifiable at many different scales with boundaries selected to highlight internal and external interactions. In this sense, an aquatic ecosystem might be identified by the dominance of water in the internal structure and functions of an area. Such systems intuitively include streams, rivers, ponds, lakes, estuaries, and oceans. Most ecologists and environmental regulators also include vegetated wetlands as members of the set of aquatic ecosystems, and many think of groundwater aquifer systems as potential members of the set. “Aquatic and related terrestrial ecosystems” is a phrase that recognizes the impossibility of analyzing aquatic systems absent consideration of the linkages to adjacent terrestrial environments.

The inclusion of “related terrestrial ecosystems” for this study is a reflection of the state of the science that recognizes the multitude of processes linking terrestrial and aquatic systems. River ecologists have long understood the important connections between rivers and their floodplains (Junk et al., 1989; Stanford et al., 1996). The inflows of water, nutrients, and sediments from surrounding watersheds are heavily influenced by conditions within the floodplain. Conversely, floodplain plant and animal habitat value and sediment supply and fertility are often determined by river hydrology. This same sort of relationship between terrestrial and aquatic system is now understood to influence many of the functions of wetlands that motivate management efforts (Wetzel, 2001). Wetland ecologists have debated for years about appropriate recognition of capacity and opportunity to perform functions when conducting assessments of wetlands. A classic example of the discussion focuses on two identical wetlands, one in a pristine forested landscape, and the other in an intensely developed landscape. Both are assumed to have equivalent internal capacities to sequester pollutants, modify nutrient loads, and provide habitat, but the surrounding conditions mean that the opportunity for these functions to occur will differ significantly.

For many of the ecosystem functions and derived services considered in this chapter, it is not possible, necessary, or appropriate to delineate clear spatial boundaries between aquatic and related terrestrial systems (see Box 3-1). Indeed, to the extent that there is an identifiable boundary, it is often dynamic in both space and time. Floods, droughts, and seasonal patterns in rainfall are inte-

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

BOX 3-1
Understanding Ecosystem Terminology

Ecology is a scientific field that studies the relationships between and among (micro)organisms such as plants, animals, and bacteria and their environment. Like most scientists, ecologists use a variety of terms to describe aspects of their discipline. A few of the terms used throughout this report are defined below in the interest of facilitating the readability and understanding of this report.

Ecosystem biodiversity describes a number and kinds of organisms in a specific geographic area that can be distinguished from other areas by its physical boundaries (e.g., lake, forest), though such boundaries can be somewhat arbitrary. In addition to biodiversity, ecosystems have properties such as the amount of plant and animal matter they produce (primary and secondary production) and the flow of chemical elements within and through the system (nutrient cycling).

Ecosystem structure refers to both the composition of the ecosystem (i.e., its various parts) and the physical and biological organization defining how those parts are organized. A leopard frog or a marsh plant such as a cattail, for example, would be considered a component of an aquatic ecosystem and hence part of its structure. The relationship between primary and secondary production would also be part of the ecosystem structure, because it reflects the organization of the parts.

Ecosystem function describes a process that takes place in an ecosystem as a result of the interactions of plants, animals, and other (micro)organisms in the ecosystem with each other or their environment and that serves some purpose. Primary production (most notably the generation of plant material) is an example of an ecosystem function. The net primary production in an ecosystem is determined by the number and kinds of plants present; the amounts of sunlight, nutrients, and water available; and the amount of this productivity used internally by the plants themselves.

Ecosystem structure and function provide various goods and services to humans that have value: for example, rare species of plants or animals, fish for recreational or commercial use, clean water to swim in or drink. The functioning of ecosystems (interaction of organisms and the physical environment) often provides for services such as water purification, recharge of groundwater, flood control, and various aesthetic qualities such as pristine mountain streams or wilderness areas.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

gral forcing functions for freshwater systems, just as tides, hurricanes, and sealevel rise constantly revise the boundaries between land and water in coastal systems. For these reasons, and as stated in Chapter 1, “aquatic ecosystems” collectively refers to aquatic and related terrestrial ecosystems unless noted otherwise.

The conceptual challenges of valuing ecosystem services involve explicit description and adequate assessment of the link (i.e., the ecological production function) between the structure and function of natural systems and the goods or services derived by humanity (see Figure 1-3). Describing structure is a relatively straightforward process, even in highly diverse ecosystems. Exceptions sometimes arise at the levels of small invertebrates and microorganisms. However, function is often difficult to infer from observed structure in natural systems. Furthermore, the relationship between ecosystem structure and function as well as how these attributes respond to disturbance are not often well understood. Indeed, ecological investigations of aquatic systems show no signs of running out of questions about how these systems operate. Without comprehensive understanding of the behavior of aquatic systems, it is clearly difficult to describe thoroughly all of the services these systems provide society. Although valuing ecosystem services that are not completely understood is possible (see Chapters 4 and 5 for further information and examples), when valuation becomes an important input in environmental decision-making, there is the risk that the valuation may be incomplete.

There have only been a few attempts to develop explicit maps of the linkage between aquatic ecosystem structure/function and value. There are, however, a multitude of efforts to separately identify ecosystem functions, goods, services, values, and/or other elements in the linkage without developing a comprehensive argument. One consequence of this disconnect is a diverse literature that suffers somewhat from indistinct terminology, highly variable perspectives, and considerable divergent convictions. Despite these shortcomings, the core issue of how to assess and value aquatic ecosystem services is intuitive and important enough to support some synthesis—especially as related to environmental decision-making.

The goal of this chapter is to review and summarize some of the common elements in the published literature concerning the identification of aquatic ecosystem functions and their linkage to goods and services for subsequent economic valuation. It also includes a summary review of the extent and status of aquatic ecosystems in the United States and some of the issues that continue to complicate efforts to value aquatic ecosystem services. The chapter closes with a summary of its conclusions and recommendations.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

EXTENT AND STATUS OF AQUATIC AND RELATED TERRESTRIAL ECOSYSTEMS IN THE UNITED STATES

There are impressive examples of almost every kind of aquatic ecosystem within the United States. The country has some of the largest freshwater lakes in the world (see Box 3-2), one of the world’s largest river systems (see Box 3-3), one of the world’s largest estuaries (see Box 3-4), thousands of miles of coastline, extensive underground aquifers (see Box 3-5), a vast array of tidal and nontidal wetlands (see Box 3-6), and so many small creeks and streams that they are still being mapped. There is a long history of efforts to understand and manage these resources for public and private benefit, and the need to make informed decisions continues to motivate both research and monitoring. These short summaries identify some of the ways that humans have used and benefited from these ecosystems over time and many of the ecosystem services that managers seek to value in efforts to inform decisions. The summaries also identify some of the key management issues that have arisen as a result of evolving and often conflicting interests regarding ecosystem services.

In 2002, U.S. Environmental Protection Agency (EPA) released the 2000 National Water Quality Inventory (NWQI; EPA, 2002)—the thirteenth installment in a series that began in 1975. These reports are required by Section 305(b) of the Clean Water Act and are considered by EPA to be the primary vehicle for informing Congress and the public about general water quality conditions in the United States. As such, the reports characterize water quality, identify widespread water quality problems of national significance, and describe various programs implemented to restore and protect U.S. waters. Notably, these assessments include streams and rivers, lakes and ponds, coastal resources to include tidal estuaries, shoreline waters (coastal and Great Lakes), and wetlands. Table 3-1 summarizes some of the relevant results and findings from the 2002 NWQI report.1

Although EPA, various federal and state partners, and other nongovernmental organizations and scientists have been assessing the condition of estuaries for decades, the National Coastal Condition Report (NCCR; EPA, 2001) represents the first comprehensive summary of coastal conditions in the United States and uses data and information collected from 1990 to 2000.2 The report, a coordinated effort between EPA (lead), the National Oceanic and Atmospheric Administration (NOAA), the U.S. Geological Survey (USGS), and the U.S. Fish and Wildlife Service (USFWS), compiles and summarizes several data sets from

1  

The NWQI report includes information about water quality standards, detailed summaries of the results of waterbody assessments by designated uses and states, and a discussion of the data collection and analysis methods used in that report.

2  

Interested readers are directed to the NCCR report (EPA, 2001) for further information and details on the findings as well as data collection and analysis methods used to generate and interpret the regional results. Notably, Chapter 1 of that report includes a comprehensive list of federal programs and initiatives that address coastal issues, many of which are conducted jointly with various coastal states and local organizations.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

BOX 3-2
Great Lakes Ecosystem

The Great Lakes ecosystem is the largest freshwater system in the world, comprising Lakes Michigan, Superior, Huron, Erie, and Ontario. Collectively, they cover a land area of 94,000 square miles and contain 5,500 cubic miles of water in the United States and Canada. Rivers and streams running into the lakes drain 201,000 square miles of land. Rain that falls in Chicago or Duluth may eventually leave the ecosystem more than 1,000 water miles to the east at Montreal, although outflows of water and its solutes are small, less than 1 percent by volume per year.

Habitats within the ecosystem are diverse. In the north, forests surrounding Lake Superior support healthy populations of black bears, bald eagles, wolves, and moose. Waterfowl, songbirds, and raptors funnel between Lakes Michigan and Erie during the spring and fall migrations. Lakes, wetlands, and uplands across the basin provide a mixture of habitats for temperate plants and animals of many types. The beaches and dunes of the southern shores are nesting areas for open water birds and wading birds such as the endangered piping plover.

Mining, timbering, agriculture, and industry brought major changes to the ecosystem beginning in the 1800s. Industries of all sorts grew up on the shorelines of lakes and rivers and used these waterbodies to facilitate both waste disposal and shipping. New locks and canals between the lakes allowed access to the Atlantic, while also opening pathways for the introduction of exotic species. For example, saltwater alewives displaced native species and sea lamprey devastated Great Lakes trout populations. Although industry created great wealth and well-being, it also left behind vast quantities of waste, including residues of dichlorodiphenyltrichloroethane and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT), polychlorinated biphenyls (PCBs), and heavy metals. Sewage and soil erosion turned lake water from clear blue to dark green through eutrophication.

Different trends began in the 1960s. Economic and public policy changes began to stem the flow of pollutants into the system, while aging mines, mills, and refineries closed. Electricity and natural gas replaced coal for heating, and air pollution laws cut power plant and automobile emissions. DDT and PCBs were banned, and the use of heavy metals declined. Treaties with Canada and interstate agreements established ecosystem-wide authorities to identify environmental problems and implement solutions. Marked changes in the former ecosystem followed these economic and regulatory changes. Water quality gradually improved so that the “oligotrophic blue” is reestablished in all the lakes. Between 1974 and 1994, PCB levels in top-of-the-food-web predators dropped by as much as 90 percent. Bald eagles once again breed along lake and river shorelines, and shoreline beaches and dunes are major summer destinations. Boating and recreational fishing are multibillion dollar industries.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

However, history and the daily activities of 33 million people present continuing challenges for the ecosystem. Old harbors and shipping points are still lined by millions of tons of toxic materials and sediments. Although ambient concentrations are low, persistent toxic materials are concentrated by the ecosystem and food web, and levels of metals and PCBs in the blood and tissue of fish, waterfowl, and birds of prey are still high. Fish consumption advisories for recreational anglers remain in effect in across the region, and further reductions in mercury use and emissions remain a regulatory priority.

Restoring habitat and native species is also a priority. Wetland regulations halted the destruction of rare wetland types such as cedar bogs, fens, and salt marshes. Wetland restoration aims at restoring scarce wetland types, especially those along Great Lakes shorelines and bird migration routes. Elk and moose are reestablished in some areas, and significant efforts are under way to strengthen populations of Lake Superior native clams, walleye, brook trout, and sturgeons. Invasive and exotic species such as zebra mussels, lamprey, ruffe, and goby, however, continue to displace and threaten native species.

The Great Lakes region can be viewed a continuing experiment in testing human capability to live and prosper within the bounds of a major aquatic ecosystem, and although the last four decades allow some optimism, major environmental problems remain. During storms, combined sewer and stormwater drainage systems overflow, releasing untreated sewage in otherwise protected waterbodies. Urban and agricultural runoff contribute excessive nutrients into susceptible bays and inlets. Toxic air emissions disperse trace contaminants across the region, feeding the cycle of bioaccumulation. Success in this Great Lakes experiment will not be accidental. Thus, careful choices must be made and subsequent actions taken.

SOURCE: Great Lakes National Program Office (2001, 2002).

federal and state coastal monitoring programs to present a broad baseline picture of the condition of U.S. coastal waters as divided into five discrete regions: Northeast, Southeast, Great Lakes, Gulf of Mexico, and West Coast. The report is intended to serve as a benchmark for assessing the progress of coastal programs in the future and will be followed by subsequent reports on more specialized coastal issues.

It is important to note that the condition of U.S. coastal waters is described primarily in terms of data on estuaries, which are loosely defined in the NCCR as the productive transition areas between freshwater rivers and the ocean. In addition, although the intent of the report is to evaluate the condition of coastal waters (i.e., primarily estuaries) nationwide, the report states that there was insufficient information to completely assess West Coast estuaries and the Great

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

BOX 3-3
The Missouri River Ecosystem

The Missouri River basin extends over 530,000 square miles and covers approximately one-sixth of the continental United States. The one-hundredth meridian, the widely accepted boundary between the arid western states and the more humid states in the eastern United States, crosses the middle of the basin. The Missouri River’s source streams are in the Bitterroot Mountains of northwestern Wyoming and southwestern Montana. The Missouri River begins at Three Forks, Montana, where the Gallatin, Jefferson, and Madison Rivers merge on a low, alluvial plain. From there, the river flows to the east and southeast to its confluence with the Mississippi River just above St. Louis. Near the end of the nineteenth century, the Missouri River’s length was measured at 2,546 miles.

Between 1804 and 1806, the famous explorers Meriwether Lewis and William Clark led the first recorded upstream expedition from the river’s mouth at St. Louis to the Three Forks of the Missouri, and eventually reached the Pacific coast via the Columbia River. The Missouri River subsequently became a corridor for exploration, settlement, and commerce in the nineteenth and early twentieth centuries, as navigation extended upstream from St. Louis to Fort Benton, Montana. Social values and goals in the Missouri River basin during this period reflected national trends and the preferences of basin inhabitants. Statehood, federalism, and regional demands to develop and control the river produced a physical and institutional setting that generated demands from a wide range of interests.

The Missouri River ecosystem experienced a marked ecological transformation during the twentieth century. At the beginning of the century, the Missouri River was notorious for large floods, a sinuous and meandering river channel that moved freely across its floodplain, and massive sediment transport. However, by the end of the twentieth century, the Missouri River bore little resemblance to the previously wild, free-flowing river. Over time, demands for the benefits associated with the Missouri’s control and management resulted in significant and lasting physical and hydrologic modifications of the river. These modifications led to substantial changes in the river and floodplain ecosystem. Numerous reservoirs are scattered across the basin, with seven large dams and reservoirs located on the river’s mainstem.

Ecological changes that accompanied changes in hydrology proceeded more slowly but were of a similar magnitude. Large floodplain areas along the upper Missouri were inundated by the reservoirs, and large areas of native vegetation communities in downstream floodplains were converted into farmland. Many native fish and avian species experienced substantial reductions, while nonnative species—especially fish—thrived in some areas. The rich biodiversity of the pre-regulated Missouri River ecosystem was sustained through a regime of natural disturbances that included periodic floods and attendant sediment erosion and deposition. These disturbances, in turn, supported a variety of ecological benefits, including commercial and recreational fishing, timber,

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

wild game, trapping and fur production, clean water, soil replenishment processes, and natural recharge of groundwater. Flow regulation and channelization substantially changed the Missouri River’s historic hydrologic and geomorphic regimes. The isolation of the Missouri River from its floodplain caused by river regulation structures has in many stretches largely eliminated the flood pulse and its ecological functions and services. As a result of these changes, the production and the diversity of the ecosystem have both markedly declined.

For purposes of comparison, the major benefits of river regulation come from hydropower, water supply, and flood damage reduction, each of which has annual benefits measured in hundreds of millions of dollars. Recreation comes next, with annual benefits measured in tens of millions of dollars. Navigation follows, with annual benefits measured in millions of dollars. The value of ecosystem services that have been forgone in order to achieve other benefits is largely unknown.

Today the Missouri River floodplain ecosystem consists of extensive ecosystems in and around the large reservoirs, open reaches of channel, and riparian floodplains. Some of these systems are recognized producers of recreational opportunities or agriculture. Some traditional ecosysems, particularly those representing the historical habitats of the pre-regulated Missouri, have been less well recognized for the social values provided through ecosystem services. Many ecosystem services, such as fish, game, and aesthetic values, are not monetized and are not traded in markets. They thus tend to be underappreciated and undervalued by the public and by decision-makers.

SOURCE: NRC (2002b).

Lakes, and no assessment was possible for the estuarine systems of Alaska, Hawaii, and other island territories. However, new ecological programs, both newly created and proposed, should permit a comprehensive and consistent assessment of all of the nation’s coastal resources by 2005. The NCCR used aggregate scores for a total of seven water quality indicators (water clarity, dissolved oxygen, coastal wetland loss, contaminated sediments, benthos, fish tissue contaminants, and eutrophic condition); 56 percent of assessed estuarine areas (representing more than 70 percent of the estuarine areas of the conterminous United States, excluding Alaska) were found to be in good condition for supporting aquatic life use (plant and animal communities) and human uses (e.g., water supply, recreation, agriculture). In contrast, 44 percent of the nation’s estuaries were characterized as impaired for human use (10 percent), aquatic life use (11 percent), or both (23 percent). In general, the nation’s coastal areas were rated as poor if the mean conditions for the seven indicators showed that more than 20 percent of the estuarine area in that region was degraded.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

BOX 3-4
Chesapeake Bay

The Chesapeake Bay is the largest estuary in the United States and among the largest in the world. The watershed spreads over approximately 64,000 square miles, encompassing major portions of Pennsylvania, Maryland, and Virginia; all of the District of Columbia; and lesser portions of New York, West Virginia, and Delaware. It receives freshwater from six major rivers and has more than 2,000 square miles of relatively protected tidal waters.

The bay has been prized by its human inhabitants for centuries for its ability to provide food, water, navigation, waste disposal, recreation, and aesthetic pleasures. The estuary supports extensive commercial and recreational fisheries for striped bass, menhaden, flounder, perch, and many others. Oyster, crab, and clam harvests have supported local fishermen for generations. In addition, important habitat is provided for sea turtles, sharks, rays, eels, whelks, and an enormous diversity of waterfowl.

Hampton Roads located at the mouth of the bay in Virginia and Baltimore near the head of the bay in Maryland are among the nation’s largest ports. Hampton Roads is home to the world’s largest naval base, and both ports contain major international shipping terminals. Shipbuilding and repair are major industries in the regional economy. The value of commercial navigation in the bay is rivaled by the tremendous investment in recreational boating that operates from hundreds of marinas and thousands of private docks. The more than 20,000 miles of tidal shoreline in the system also provide highly desired home locations for many of the area’s residents.

All of these benefits have led to intensive and continually increasing pressure on the ecosystem as human populations in the region have increased and subsequent use has escalated. One consequence has been emergence of the Chesapeake Bay as one of the most extensively studied estuaries in the world. Interest in the system has been driven by concern for declines in finfish and shellfish populations. These trends are recognized as the result of overharvesting, pollution, habitat destruction, and introduced diseases. The challenge of restoring the system’s productivity has motivated investment of millions of dollars of public funds through the Chesapeake Bay Program, a cooperative effort by states and the federal government to reduce impacts and improve conditions in the ecosystem. The extensive and complex array of stakeholder groups, commitments, and programs orchestrated under the umbrella of this program has become a model for similar efforts emerging in other large aquatic ecosystems.

The current focus of the Chesapeake Bay Program is on reduction of nutrient, sediment, and toxic inputs to the system. This is being accomplished through the use of state-of-the-art simulation models, extensive monitoring, outreach and education, and a mix of regulatory and nonregulatory programs to design and implement best management practices throughout the watershed.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Parallel efforts are under way to restore vital habitats such as wetlands, submerged aquatic vegetation, and oyster reefs; promulgate multispecies and ecosystem management plans; and control the impacts of continuing development.

Estimates of the funding necessary to achieve restoration goals in the Chesapeake Bay extend into the tens of billions of dollars. This amount exceeds currently available resources by several orders of magnitude, creating unavoidable need to prioritize such efforts. To date, the incorporation of economic valuation in bay program management has been informal. Although cost-benefit analyses are implicit in almost every budget decision for Program activities, explicit use of economic assessments is not a characteristic of program management.

SOURCE: Scientific and Technical Advisory Committee (2003).

BOX 3-5
The Edwards Aquifer and Groundwater Recharge in San Antonio, Texas

The Edwards Aquifer of central Texas is a highly permeable karst limestone on the edge of the Chihuahuan Desert. The average annual temperature is 20.5°C average annual precipitation is 28.82 inches. The annual recharge for the aquifer ranges from 44,000 to 2,000,000 acre-feet and averages 635,500 acre-feet per year. Thousands of springs flow from this groundwater source, including the largest springs in the state, and potable water is the primary use of the groundwater supply (Bowles and Arsuffi, 1993). Recharge of the aquifer has been monitored by the U.S. Geological Survey (USGS) since 1915, while water quality monitoring began in 1930.

Currently, more than 1.7 million people rely on the Edwards Aquifer. However, recharge of the porous karstic limestone occurs primarily during wet years when precipitation infiltrates deeply into the soils and underlying rock. As a result, new laws were introduced that changed the legal basis of ownership from “right of capture” for a demonstrated “beneficial use” of the extracted water to a new approach based on prior appropriation (i.e., senior water rights). Concern increased as several springs (Comal, San Antonio, San Pedro) in the area began to dry up following a seven-year drought in the 1950s. Groundwater storage is critical in most aquatic ecosystems to provide persistent springs and streams during drought. Diverse microbial communities and a wide range of invertebrate

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

and vertebrate species live in groundwaters (Gibert et al., 1994; Jones and Mulholland, 2000). Their main ecosystem functions are breaking down organic matter and turning dead materials (detritus) into live biomass that is consumed in food webs. Thus, these species recycle nutrients and are important in secondary productivity. The trade-offs in extracting groundwater include possible loss of habitat for endemic species that are protected by state and federal regulations. For example, the Edwards Aquifer-Comal Springs ecosystem provides critical habitat for the Texas blind salamander (Crowe and Sharp, 1997; Edwards et al., 1989). Moreover, 91 species and subspecies of fish are endemic in this underground ecosystem (Bowles and Arsuffi, 1993; Culver et al., 2000; Longley, 1986). Several economic values of groundwater are associated with ecosystem services such as processing of organic matter by diverse microbes and invertebrates, providing possible dilution of some types of surface-originating contaminants, and sustaining populations of rare and endangered species that are often restricted to very local habitats (Culver et al., 2000).

By 1970, new regulations were issued to protect water quality in the Edwards Aquifer. These new rules limited economic development within the recharge zone to balance the long-term average recharge rate with the extraction rate. This steady-state equilibrium, however, is often characterized by time lags in recharge and drought frequencies that complicate predictable levels of water supply. Other physical considerations include how much and what types of development occur without disrupting rapid infiltration of the recharge zone. Degradation of subsurface water quality as well as declines in rates of recharge occur when economic development increases the extent of impervious surfaces that, in turn, cause more rapid runoff and loss of infiltration during and after precipitation events. The increased surface area of roof tops, roads, parking lots, and so on changes stormwater and groundwater hydrology and water chemistry. As groundwater is depleted the cost for deeper drilling and pumping increases costs and can terminate or slow the rate of extraction. Thus, it is difficult to consistently define “overextraction.” The rate of extraction depends on future values relative to current values under specific alternative uses and climatic conditions (Custodio, 2002).

The Texas legislature created the Edwards Aquifer Authority to control pumping and to reallocate water through market mechanisms (Kaiser and Phillips, 1998; McCarl et al., 1999; Schaible et al., 1999). This approach has reallocated water from lower economic uses (e.g., agricultural irrigation) to higher-valued uses (e.g., for domestic and industrial water supplies and environmental and recreational uses). Especially during dry years, it appears feasible for transfers from irrigation to offset demands for municipal water supplies. In 1997, farmers accepted an offer of $90 per acre prior to the cropping season in a pilot study of the Irrigation Suspension Program (Keplinger and McCarl, 2000; Keplin-

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

ger et al., 1998). Drought increases the demand for water while the supply declines. Chen et al. (2001) used a climate change model to estimate the regional loss of welfare at $2.2 million to $6.8 million per year from prolonged drought. To protect endangered species in springs and groundwater, an additional reduction of 9 to 20 percent in pumping would add $0.5 million to $2 million in costs.

Traditionally, the only costs for the use of groundwater was the expense of installing a well and paying for pumping of this “open-access, free resource.” However, when rates of extraction exceed recharge, the reduction in water levels may exceed an uncertain threshold, and cause irreversible changes. For example, removal of water in the underground area may cause collapse of the overlying substrata. These collapses decrease future storage capacity below ground and can alter land values. In some areas the depleted groundwater may cause intrusion of low-quality water from other aquifers or from marine-derived salt or brackish waters that could not readily be restored for freshwater storage and use. Contamination of groundwater from landfills, leaking petroleum storage tanks, and pesticides can also makes aquifers unusable.

In 1993 the Sierra Club sued the state for failure to guarantee a minimum flow of 100 cubic feet per second (cfs) to Comal and San Marcos Springs. The State of Texas and the U.S. Fish and Wildlife Service have entered into an agreement to resolve this conflict. To avoid jeopardizing the endangered species living in these springs, the Edwards Aquifer Authority banned the use of irrigation sprinklers whenever flow declined below a threshold that limited habitat in the Comal Springs. Approximately 1.5 million people were affected when the USGS reported that the flow declined to 145 cfs in September 2002. Limited pumping also had large economic consequences on agriculture. While water markets may ultimately resolve reallocation issues among stakeholders in the Edwards Aquifer region (Chang and Griffin, 1992; Kaiser and Phillips, 1998; McCarl et al., 1999; Schaible et al., 1999), the predictability of water markets as suppliers of water for different needs is complex and will help reallocate water only if some level of supply is available.

The construction of water-transfer pipelines and additional surface storage reservoirs is under consideration along with conjunctive storage (pumping water into sub-surface storage associated with aquifers.) The estimated cost of building a surface reservoir (Applewhite) to provide an additional 170,000 acre-feet of water for sale was $317 per acre-foot compared to $67 per acre-foot if pumped from the Edwards Aquifer (John Merrifield, University of Texas-San Antonio, personal communication, 2003). The combination of climatic change (more extremes in drought and in distribution of rainfall) and increased human population growth will stress the current rules on allocation of water to maintain natural ecosystem functions and survival of endangered species.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

BOX 3-6
The South Florida Ecosystem

South Florida is dominated by the waters of the Kissimmee-Ockeechobee-Everglades (KOE) ecosystem. In the late summer and fall, rainfall enters the Kissimmee River near Orlando and gradually flows south to Lake Ockeechobee. The waters gather more rainfall and continue south, flowing into agricultural fields, an extensive system of flood control canals and reservoirs, and the “river of grass” called the Everglades. Eventually, the waters flow through the Everglades to enrich the mangrove forests and estuaries on the Atlantic and Gulf Coasts (Purdum, 2002).

The KOE ecosystem covers almost 17,000 square miles in South Florida. The ecosystem is home to more than 6 million people and the dynamic regional economies of Orlando and South Florida, including the cities of Miami, Fort Lauderdale, and West Palm Beach. The ecosystem’s preserves and natural areas are known throughout the world for their uniqueness and beauty: including the Everglades National Park, Big Cypress Preserve, the Florida Keys, Biscayne Bay, and the estuary of Florida Bay (NRC, 2002a, 2003).

The ecosystem is a mix of natural and human forces. Ten thousand years ago, the KOE area was dry prairie, inhabited by horses, camels, bison, and mammoths and the humans who hunted them. About 9,000 years ago, the oceans began to rise with the ending of the last ice age. The habitat shifted as the climate changed to humid subtropics in the north and tropical savannah in the south (Purdum, 2002). Swamps, marshes, pinelands, the everglades, and hard-wood hammocks developed in inland areas, sustained by the gradual flow of waters. Mangroves and estuaries gained a footing in coastal areas. Tropical and subtropical wildlife grew in abundance, ranging from crocodiles to bear to birds in wide variety.

In the last 100 years, the annual tropical cycle of sun in the winter drought and dependable rain in the summer and fall attracted residents from around the world, but torrential rains caused flooding. As settlements grew, there was a steady human effort to control and redirect the annual flooding. Some redirected water went to serve urban and agricultural uses, but much was simply channeled into the ocean.

By the end of the twentieth century, the KOE ecosystem was criscrossed by more than 1,800 miles of canals and levees, controlling the floods but also cutting off the established flows of KOE water. Water became scarce in humid area such as the Everglades and Florida Bay estuaries. Some species were particularly hard hit. Nesting wading birds declined by 90 percent (Lord, 1993). Saltwater began to intrude into freshwater aquifers supplying 90 percent of potable water for the human population (Purdum, 2002).

Major investments are now being made to restore the quantity of water available and its flow through the remaining natural systems. One significant project is the $7.8 billion Everglades Restoration Plan (see NRC, 2002a; 2003). The plan proposes to remove major barriers to water flows into Everglades National Park, treat surface water runoff from urban areas, reuse wastewater, and store water from heavy rainfall rather than shunting it out to sea (Purdum, 2002). The project is expensive, but is it enough given the value of ecosystem resources and services? Methods for valuing ecosystem services would help provide an answer.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Table 3-1 Selected Findings and Results from the 2002 National Water Quality Resource Inventory

Waterbody Type

Total Sizea

Amountb Assessed (% of total)

Goodc (% of assessed)

Impairedd (% of assessed)

Leading Pollutants and Causes of Impairmente

Leading Sources of impairmente

Notes

Rivers and streams

3,692,830 miles

699,946 miles (19%)

426,633 miles (61%)

269,258 miles (39%)

Pathogens (bacteria)

Siltation

Habitat alteration

Oxygen-depleting substances

Nutrients

Thermal modification

Metals

Flow alteration

Agriculture

Hydrologic modifications

Urban runoff and storm sewers

Forestry

Municipal point sources

Resource extraction

See Chapter 2 and Appendix A of EPA (2002) for further information

Lakes, reservoirs, and ponds

40,603,893 acres

17,339,080 acres (43%)

9,375,891 acres (55%)

7,702,370 acres (45%)

Nutrients

Metals

Siltation

Total dissolved solids

Oxygen-depleting substances

Excess algal growth

Pesticides

Agriculture

Hydrologic modifications

Urban runoff and storm sewers

Atmospheric deposition

Municipal point sources

Land disposal

See Chapter 3 and Appendix B of EPA (2002) for further information

Coastal resources: Estuaries

87,369 sq. miles

31,072 sq. miles (36%)

14,873 sq. miles (49%)

15,676 sq. miles (51%)

Metals

Pesticides

Oxygen-depleting substances

Pathogens (bacteria)

Priority toxic organic chemicals

Polychlorinated biphenyls (PCBs)

Total dissolved solids

Municipal point sources

Urban runoff/storm sewers

Industrial discharges

Atmospheric deposition

Agriculture

Hydrologic modifications

Resource extraction

See Chapter 4 and Appendix C of EPA, 2002 for further information

Coastal resources: Great Lakes shoreline

5,521 miles

5,066 miles (92%)

1,095 miles (22%)

3,955 miles (78%)

Priority toxic organic chemicals

Nutrients

Pathogens (bacteria)

Sedimentation and Siltation

Oxygen-depleting substances

Taste and odor

PCBs

Contaminated sediments

Urban runoff and storm sewers

Agriculture

Atmospheric deposition

Habitat modification

Land disposal

Septic tanks

See Chapter 4 and Appendix F of EPA (2002) for further information

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Waterbody Type

Total Sizea

Amountb Assessed (% of total)

Goodc (% of assessed)

Impairmentd (% of assessed)

Leading Pollutants and Causes of Impairmente

Leading Sources of Impairmente

Notes

Coastal resources: Ocean shoreline waters

58,618 miles

3,221 miles (6%)

2,755 miles (86%)

434 miles (14%)

Pathogens (bacteria)

Oxygen-depleting substances

Turbidity

Suspended solids

Oil and grease

Metals

Nutrients

Urban runoff and strom sewers

Nonpoint sources

Land disposal

Septic tanks

Municipal point sources

Industrial discharges

Construction

See Chapter 4 and Appendix C of EPA (2002) for further information

Wetlands

105,500,000 acresf

8,282,133 acres (8%)

4,839,148 acres (58%)

3,442,985 acres (42%)

Sedimentation and siltation

Flow alterations

Nutrients

Filling and draining

Habitat alterations

Metals

Agriculture

Construction

Hydrologic modifications

Urban runoff

Silviculture

Habitat modifications

See Chapter 5 and Appendix D of EPA (2002) for further information

aUnits are miles for rivers and streams; acres for lakes, reservoirs, ponds, and wetlands; square (sq.) miles for coastal resources (estuaries, Great Lake shoreline, and ocean shoreline waters).

b Includes waterbodies assessed as not attainable for one or more designated uses (i.e., total number ofwaterbody units assessed as good and impaired do not necessarily add up to total assessed).

c Fully supporting all designated uses or fully supporting all uses, but threatened for one or more uses.

d Partially or not supporting one or more designated uses.

e For those states and jurisdictions that reported this type of information (i.e., olten a subset of the total number of states and jurisdictions that assessed and reported on various waterbodies; see EPA 2002 for further information).

f From Status and Trends of Wet/ands in the Conterminous United States 1986 to 1997 (Dahl, 2000).

SOURCE: Adapted from EPA (2002).

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Section 401 of the Emergency Wetlands Resources Act of 1986 requires the USFWS to conduct studies of the status and trends of the nation’s wetlands and report the results to Congress each decade. The third report of the USFWS’s National Wetlands Inventory (NWI), Status and Trends of the Wetlands in the Conterminous United States 1986 to 1997, was released in 2000 (Dahl, 2000). This NWI report provides the most recent and comprehensive estimates of the areal extent (status) and trends of wetlands in the conterminous 48 United States on all public and private lands between 1986 and 1997. In that report, wetlands, deepwater, and upland (land-use) categories are divided into a wide variety of habitats and groupings; however, wetlands are classified principally as estuarine and marine wetlands and freshwater wetlands.3 The study design included 4,375 randomly selected sample plots 4 square miles in area that were examined using remotely sensed data in conjunction with fieldwork and verification to determine wetland change. However, the report does not address water quality conditions or provide an assessment of wetland functions.

As of 1997, the lower 48 states contained about 105.5 million acres of wetlands of all types (Dahl, 2000), an area about the size of California. Of these, about 95 percent are inland freshwater wetlands, while the remaining 5 percent are saltwater (marine and estuarine) wetlands. Between 1986 and 1997, the net loss of wetlands was 644,000 acres with an annual loss rate of 58,545 acres (see also Table 1-1); 98 percent of these losses occurred in freshwater wetlands.4

A fourth major federal program report related to the extent and status of aquatic and related terrestrial ecosystems is the Summary Report of the 1997 National Resources Inventory (Revised December 2000) (USDA, 2000). The NRI is conducted every five years by the U.S. Department of Agriculture’s Natural Resources Conservation Service in cooperation with the Iowa State University Statistical Laboratory. The 1997 NRI report is the fourth summary report in a series that began in 1982 and is a scientifically based, longitudinal panel survey designed to consistently assess conditions and trends of the nation’s soil, water, and related resources for all nonfederal lands for all 50 states and other jurisdictions (e.g., Puerto Rico) using photo interpretation and other remote sensing methods and techniques. Thus, all values provided in the 1997 NRI report are estimates based on data collected at sample sites, not data taken from a census.5

3  

See Table 1 and Appendixes A through B in Dahl, 2000 for further information.

4  

This and other USFWS’s NWI reports, their data, resources, and other information are available on-line at http://wetlands.fws.gov. Accessed June 11, 2004.

5  

The 1997 NRI report has detailed information on study design, data collection methods, compilation, synthesis, and analysis, in addition to the resource inventory results.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

CATALOGING ECOSYSTEM STRUCTURE AND FUNCTION AND MAPPING ECOSYSTEM GOODS AND SERVICES

Ecosystem Structure and Function

As a general rule, the literature on ecosystem valuation attempts to use the terms “structure” and “function” as descriptors of natural systems (i.e., free of “value” content; see Chapter 2 for further discussion). These are features of natural systems that result in a capacity to provide goods and services, which can in turn be valued by humans (see also Box 3-7). The “value-free” distinction is ultimately blurred when considering intrinsic values of natural systems, but identification of ecosystem structure and function is a reasonable starting point for the subsequent mapping of ecosystem goods and services.

There are at least three key elements in the effective description of aquatic ecosystems: (1) geomorphology, (2) hydrology, and (3) biology. Collectively, these factors constrain the stocks of organic and inorganic materials in the system and the internal and external fluxes of those materials and energy. For this reason, many classification efforts focus on these three elements in developing taxonomies of aquatic ecosystems.

BOX 3-7
Energy Analysis and Valuation

Some ecologists use energetics (Odum, 1988, 1996) as a common currency for valuation. More specifically, energetic valuation (Odum and Odum, 2000) attempts to put the contributions of the economy on the same basis as the work of the environment by using one kind of energy (e.g., solar energy) as the common denominator. Accordingly, the term “emergy” was proposed to express all values in one kind of energy required to produce designated goods and services, for the purpose of eliminating confusion with other energetic valuation concepts (Odum, 1996). As an example, to evaluate the total worth of an estuary, the total energy flow in terms of embodied energy (which represents all of the work of the ecosystem) is determined and then this energy value is converted to monetary units on the basis of the ratio between energy and money in the production of market goods (Odum, 1993).

Energetic evaluation is presented as a strategy by which ecological data can be used to influence environmental policies (Odum and Odum, 2000) and it has served as a useful tool to examine the interface between ecosystems and economics (e.g., Odum and Turner 1990; Turner et al. 1988). However, it rejects the premise that values arise from the preferences of individuals and that the fundamental purpose of economic valuation is to estimate the change in willingness to pay (or accept compensation) for the various losses and gains experienced by individuals when confronted by changes in ecosystem services.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

An example of extant classification systems is the one adopted by the NWI of the USFWS (Cowardin et al., 1979). This hierarchical system distinguishes general kinds of aquatic ecosystems (e.g., rivers, lakes, estuaries) and then places special emphasis on a site’s vegetative community and hydroperiod. The method does not purport to address function. Indeed, much of the relevant literature in wetlands ecology documents the great variability of functions within and among NWI wetland types.

A newer classification scheme developed by Brinson (1993), called the HydroGeomorphic Method (HGM), is now being developed into an assessment methodology by the U.S. Army Corps of Engineers and the EPA (Smith et al., 1995). The HGM classification places emphasis on the hydrology and topographic setting of a wetland. The classification system has become the basis for development of a growing number of wetland condition assessment models. The models support evaluation of the degree of departure from ideal or “reference” conditions for specific classes of wetlands. The assumption is that stressors in the wetland or surrounding landscape (e.g., soil disturbance, grazing, pollution discharges) will affect the natural functions of the ecosystem and that this effect can be related to observable changes in the wetland. This approach begins to establish a relationship between wetland condition and capacity to perform certain functions. Nevertheless, the natural variability of wetland ecosystems confounds simple inference about functions based simply on HGM classification.

There are similar efforts to develop classifications for lakes (e.g., Busch and Sly, 1992; Maxwell et al., 1995) and streams (e.g., Rosgen, 1994; TNC, 1997; Vannote et al., 1980). Again, each of these approaches starts with structural attributes of the system being evaluated and directly or indirectly addresses some aspect(s) of function. However, none of these efforts purport to support direct inferences about a comprehensive suite of ecological functions.

The fact that there is no explicit and invariant link between structure and function of aquatic ecosystems is part of the problem in efforts to assess all goods and services provided by these natural systems. If the behavior of a particular ecosystem is dependent not only on its composition, but also on linkages to surrounding systems and the impact of stressors, then comprehensive recognition of goods and services provided is not straightforward. The constantly evolving body of work on wetlands assessment exemplifies this challenge. Describing the structure of wetland ecosystems in terms of plant community composition, soil characteristics, and water movement is a well-developed practice with generally accepted protocols. Assessing the level of function in a wetland is, however, an exceptionally complex undertaking. As noted previously, a wetland’s “capacity” to perform a function interacts with its “opportunity” to perform the function.

In a simple example case of habitat function, the structural characteristics of a wetland determine its capacity to meet the requirements of amphibians. The amounts of open water, the seasonal patterns of soil saturation, the types of sheltering plant material, and the size of the wetland all combine to determine if the

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

wetland could support amphibians (e.g., Sousa, 1985). Landscape setting, or the larger system within which the wetland system exists, determines other factors that affect a wetland’s opportunity to reach its potential as amphibian habitat. Adjacent land use affects access, water quality, and the density of potential predator populations. These and other external factors have significant impacts on the level at which habitat functions are performed (e.g., Knutson et al., 1999). The point is that wetland ecosystem structure alone is not an adequate predictor of the amphibian habitat services provided. Thus, as a generality, mapping ecosystem goods and services does not proceed linearly from system structure.

The default response to the lack of a simple logic linking structure to function has been development of generalized lists of potential functions appropriate to broad categories of aquatic ecosystems. Researchers interested in describing the importance of natural systems to humans frequently begin by generating lists of things normally functioning ecosystems can do. The scope of these lists is not universally constant.

Review of extant attempts to identify the suite of potential functions performed by aquatic ecosystems indicates that the list continues to evolve. The wetlands literature provides one example of this progression. In the 1970s, important wetlands functions included production of plant biomass, provision of habitat, modification of water quality, flood storage, and sediment accumulation (e.g., Wass and Wright, 1969). At present, the list has been expanded considerably and now includes functions in global carbon cycles, maintenance of biodiversity, and global climate control, among others (e.g., Ewel, 2002). There is no reason to believe the list will not continue to evolve as understanding of wetlands and aquatic ecosystems increases.

There have been a number of efforts to develop and suggest a taxonomy for ecosystem functions, and they tend to converge on a generalized categorization suggested by de Groot et al. (2000). These authors argue that the cumulative list of ecosystem functions can be grouped into four primary categories: (1) regulation, (2) habitat, (3) production, and (4) information (see also Table 3-3 below for further information). As described by de Groot and colleagues, regulation functions include those processes affecting gas concentrations, water supply, nutrient cycling, waste assimilation, and population levels. Habitat functions are directly related to provision of suitable living space for an ecosystem’s flora and fauna. Production functions include primary (autotrophic) and secondary (heterotrophic) production, as well as generation of genetic material and biochemical substances. Information functions are those that provide an opportunity for cognitive development and, as such, are functions that can be realized only through human interaction.

The committee’s review of the literature and attempts to catalog ecosystem functions leads to the conclusion that the absence of a consensus taxonomy is a product of both the complexity of natural systems and the challenge of communicating across multiple disciplines. The committee could find underlying logic in many of the alternative approaches, but no single approach was without complications, and none was intuitively explanatory across disciplines or to all re-

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

viewers. For the present, this appears to be the state of the science.

Although a perfect taxonomy for ecosystem functions remains elusive, this may be less important than developing a consensus on an appropriate cumulative list of potential aquatic ecosystem functions. In this regard, de Groot et al. (2000) represent an important iteration in the process of generating a useful checklist to inform aquatic ecosystem valuation exercises. While the committee found reasons to debate aspects of the proposed listing, the value as stimulus to discussion was clear. Continued work on such compilations will enhance our ability to develop more comprehensive ecosystem valuation scenarios. In the interim, it seems that using a relatively detailed list of ecosystem functions (and goods and services; see more below) like that provided by de Groot et al. (2002) can offer guidance to help ensure some breadth to the assessment of specific ecosystems.

Unfortunately, identification of the particular functions performed by an aquatic ecosystem is only part of the assessment problem. The level at which specific ecosystem functions are performed can also vary significantly, in part because these systems can vary so widely in terms of their physical and biological composition. Thus, production functions can reach extreme levels in eutrophic ponds and estuaries or drop to very low levels in oligotrophic lakes. Climate regulation functions can occur and take on great importance at very high levels in the Great Lakes or be effectively nonexistent in small prairie potholes (wetlands). Thus, while almost all ecosystem functions can be argued to occur at some level in every aquatic ecosystem, the significance of the processes can vary from great to trivial depending on the type of system, its size, and location.

Time can be another important dimension in appropriate assessment of ecosystem function, particularly when economic valuation is the end objective. The rates at which various ecological processes occur will affect their ease of recognition and measurement. For example, habitat functions are arguably easier to identify and measure than carbon sequestration, whereas primary production is easier to assess than generation of genetic material. The frequency with which certain functions are performed can similarly influence recognition and measurement. Production may be a relatively constant or at least seasonal process, while hydroperiod modification may only occur at irregular intervals of years’ duration. Finally, the developmental state of the ecosystem will affect its capacity to sustain performance of certain functions. Most aquatic ecosystems change overtime; ponds fill in or dry up, rivers meander and get dammed, and tidal marshes erode. All of these changes alter the capacity of an ecosystem to perform functions over very short to very long time periods.

As a result of the inherent variability in both structure and functions of natural systems, there is no straight forward methodology (let alone a consensus paradigm) for comprehensive assessment of each and every type of aquatic ecosystem. The practical default approach is to work from an evolving list of potential ecosystem functions (e.g., de Groot et al., 2002; MEA, 2003) and evaluate the capacity of the system under consideration to perform each function. Essential to the process is incorporation of both spatial and temporal considera-

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

tions in developing the ecosystem assessment.

Ecosystem Goods and Services

Daily (1997) states that “ecosystem services are the conditions and processes through which natural ecosystems, and the species that make them up, sustain and fulfill human life. They maintain biodiversity and the production of ecosystem goods…” Many of the goods and services provided by aquatic ecosystems are intuitive, such as potable water sources, food production, transportation, waste removal, and contributing to landscape aesthetics. To a great extent ecologists are able to catalogue and estimate these kinds of goods and services at both small and large spatial scales. Extending those assessments of goods and services through time is more challenging as ecosystems are constantly changing.

Other, less intuitive, goods and services have been recognized only as knowledge of the global ecosystem has evolved. Some of these include maintenance of biodiversity, and contributing to biogeochemical cycles and global climate. As noted previously, it is likely that the list of potential ecosystem goods and services will continue to evolve.

Reviewers of the subject area have tried to catalog ecosystem goods and services in a variety of ways. Services are sometimes grouped from the perspective of human users into categories such as extractive and nonextractive or consumptive and nonconsumptive. A compilation of some sample lists is included in Table 3-2. Reviewers have also attempted to articulate the link between ecosystem functions and the derived goods and services. One previously noted example of this approach is the de Groot et al. (2002) taxonomy for ecosystem functions, goods, and services shown in Table 3-3.

The state of the science is such that there is no broad consensus on a comprehensive list of potential goods and services derived from aquatic ecosystems. However, there is enough similarity among proposed lists to suggest that full valuation of any particular ecosystem’s goods and services must look well beyond the amounts of water, fish, waste assimilation, and recreational use provided to individuals in direct contact with the system. At present, ecologists can quantify many of the more readily accepted goods and services, although methods may vary. It is noteworthy that the international Millennium Ecosystem Assessment (MEA) being coordinated by the United Nations Environment Programme has adopted a taxonomy of ecosystem services drawn from the de Groot et al. (2002) construct (Available on-line at http://www.millenniumassessment.org/en/index.asp). After considering a number of alternative schemes for grouping ecosystem services, the approach based on function was selected for use in the MEA. In this particular iteration, services are classified as provisioning, regulating, cultural, or supporting.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

TABLE 3-2 Lists of Ecosystem Services

Ecosystem Services (Daily, 1997)

 

Purification of air and water

 

Mitigation of floods and droughts

 

Detoxification and decomposition of wastes

 

Generation and renewal of soil and soil fertility

 

Pollination of crops and natural vegetation

 

Control of the vast majority of potential agricultural pests

 

Dispersal of seeds and translocation of nutrients

 

Maintenance of biodiversity, from which humanity has derived key elements of its agricultural, medicinal, and industrial enterprises

 

Protection from the sun’s harmful ultraviolet rays

 

Partial stabilization of climate

 

Moderation of temperature extremes and the force of winds and waves

 

Support of diverse human cultures

 

Providing aesthetic beauty and intellectual stimulation that lift the human spirit

Services Provided by Rivers, Lakes, Aquifers, and Wetlands (Postel and Carpenter, 1997)

 

Water Supply

 

 

Drinking, cooking, washing, and other household uses

 

 

Manufacturing, thermoelectric power generation, and other industrial uses

 

 

Irrigation of crops, parks, golf courses, etc.

 

 

Aquaculture

 

Supply of Goods Other Than Water

 

 

Fish

 

 

Waterfowl

 

 

Clams and mussels

 

 

Pelts

 

Nonextractive or Instream Benefits

 

 

Flood control

 

 

Transportation

 

 

Recreational swimming, boating, etc.

 

 

Pollution dilution and water quality protection

 

 

Hydroelectric generation

 

 

Bird and wildlife habitat

 

 

Soil fertilization

 

 

Enhanced property values

 

 

Nonuser values

Wetland Ecosystem Services (Ewel, 2002)

 

Biodiversity: Sustenance of Plant and Animal Life

 

 

Evolution of unique species

 

 

Production of harvested wildlife:

 

 

 

Water birds, especially waterfowl

 

 

 

Fur-bearing mammals (e.g., muskrats)

 

 

 

Reptiles (e.g., alligators)

 

 

 

Fish and shellfish

 

 

Production of wildlife for nonexploitative recreation

 

 

Production of wood and other fibers

 

Water Resources: Provision of Production Inputs

 

 

Water quality improvements

 

 

Flood mitigation and abatement

 

 

Water conservation

Global Biogeochemical Cycles: Provision of Existence Values

 

 

Carbon accumulation

 

 

Methane production

 

 

Denitrification

 

 

Sulfur reduction

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Ocean Ecosystem Services (Peterson and Lubchenco, 2002)

 

Global materials cycling

 

Transformation, detoxification, and sequestration of pollutants and societal wastes

 

Support of the coastal ocean-based recreation, tourism, and retirement industries

 

Coastal land development and valuation

 

Provision of cultural and future scientific values

 

SOURCE: Adapted from Daily (1997); Ewel (2002); Peterson and Lubchenco (2002); Postel and Carpenter (1997).

TABLE 3-3 Functions, Goods, and Services of Natural and Seminatural Ecosystems

Functions

Ecosystem Processes and Components

Goods and Services

Regulation

Maintenance of essential ecological processes and life support systems

 

Gas regulation

Role of ecosystems in biogeochemical cycles

Ultraviolet-B protection Maintenance of air quality Influence on climate

Climate regulation

Influence of land cover and biologically mediated processes

Maintenance of temperature, precipitation

Disturbance prevention

Influence of system structure on dampening environmental disturbance

Storm protection Flood dampening

Water regulation

Role of land cover in regulating runoff and river discharge

Drainage and natural irrigation

Medium for transport

Water supply

Filtering, retention, and storage of freshwater (e.g., in aquifers)

Provision of water for consumptive use

Soil retention

Role of vegetation root matrix and soil biota in soil retention

Maintenance of arable land Prevention of damage from erosion and siltation

Soil formation

Weathering of rock, accumulation of organic matter

Maintenance of productivity on arable land

Nutrient regulation

Role of biota in storage and recycling of nutrients

Maintenance of productive ecosystems

Waste treatment

Role of vegetation and biota in removal or breakdown of xenic nutrients and compounds

Pollution control and detoxification

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Functions

Ecosystem Processes and Components

Goods and Services

Pollination

Role of biota in movement of floral gametes

Pollination of wild plants species

Biological control

Population control through trophic-dynamic relations

Control of pests and diseases

Habitat

Providing habitat (suitable living space) for wild plant and animal species

 

Refugium

Suitable living space for wild plants and animals

Maintenance of biological and genetic diversity

Maintenance of commercially Harvested species

Nursery

Suitable reproductive habitat

Hunting; gathering of fish, game, fruit, etc.

Aquaculture

Production

Provision of natural resources

 

Food

Conversion of solar energy into edible plants and animals

Building and manufacturing

Fuel and energy

Fodder and fertilizer

Raw materials

Conversion of solar energy into biomass for human construction and other uses

Improve crop resistance to pathogens and pests

Genetic resources

Genetic material and evolution in wild plants and animals

Drugs and pharmaceuticals

Chemical models and tools

Test and assay organisms

Medicinal resources

Variety of (bio)chemical substances in, and other medicinal uses of, natural biota

 

Ornamental resources

Variety of biota in natural ecosystems with (potential) ornamental use

Resources for fashion, handicraft, worship, decoration, etc.

Information

Providing opportunities for cognitive development

 

Aesthetic

Attractive landscape features

Enjoyment of scenery

Recreation

Variety in landscapes with (potential) recreational uses

Ecotourism

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Functions

Ecosystem Processes and Components

Goods and Services

Cultural and artistic

Variety in natural features with cultural and artistic value

Inspiration for creative activities

Spiritual and historic

Variety in natural features with spiritual and historic value

Use of nature for religious or historic purposes

Science and education

Variety in nature with scientific and educational value

Use of nature for education and research

 

SOURCE: Adapted from de Groot et al. (2002).

ISSUES AFFECTING IDENTIFICATION OF GOODS AND SERVICES

Ecosystems vary in time and space. As ecologists extend their analyses of ecosystem structure and function to include potential goods and services, the uncertainty affecting assessments increases across both time and space. The interaction of ecological and social systems makes extrapolation of observations and prediction of future conditions exceptionally complex (Berkes et al., 2003; Gunderson and Holling, 2002; Gunderson and Pritchard, 2002). The challenges arise from the heterogeneity of ecosystems and values across space which complicates aggregation for assessment at larger scales, and from nonlinear system behavior that confounds forecasting. Recognition of the thresholds of change in both space and time is one of the principal challenges in ecological research.

Scale

It may be argued that almost all ecosystem functions can be performed by aquatic ecosystems at any scale. Indeed, Limburg et al. (2002) found that scaling rules describing production and delivery of ecosystem services are yet to be formulated and quantified (as noted in the preceding sections). However, there are clearly thresholds in the level of their relative importance. For example, individual wetlands in a watershed may each have the capacity to slow the flow of waters moving through them, but this function becomes important only when there are a sufficient number of wetlands in a watershed to significantly alter the flow of floodwaters downstream.

The complication in assessment of ecosystem goods and services arises because the scale at which functions become important is not always the same.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Continuing with the watershed example above, each wetland may have the capacity to accrete organic matter, sequestering carbon. However, the significance of this function for carbon cycles may not be realized at any scale less than all of the nation’s wetlands. Alternatively, the provision of suitable habitat for a rare plant may be regionally significant at the scale of a single wetland.

Some generalizations regarding recognition of ecosystem services across scales may be possible (see Table 3-4 for one example). The problem is recognition of the thresholds at resolution sufficient to inform management and policy decisions. Knowing precisely the scale at which services can be realized is a practical challenge. Success in identification of these scale thresholds would increase opportunities for accurate recognition and appropriate economic valuation of ecosystem services.

Another challenge in valuing ecosystem services across scales arises in attempts to aggregate such information. The complex nature of ecosystems means that many interrelationships and feedback loops may operate at scales above the level of individual service assessment. Protection of wetlands important as habitat for migrating waterfowl may be undermined by loss of wetlands at other critical points on the flyway. Restoration of wetlands as nursery grounds for fish along the Louisiana coast may be less successful if nutrient pollution in the Mississippi River degrades open water habitat for the adult populations. The implication is that aggregation of service values to larger scales or composite system evaluations will almost axiomatically misrepresent the processes at the

TABLE 3-4 Examples of the Generation of Ecosystem Services at Different Scales for Aquatic Ecosystems

Time or Space Scale (day) (meters)

Aquatic Ecosystem

Example of Ecosystem Service

Scale at Which Service is Valued

10-6 to 10-5

Bacteria

Nutrient uptake and production of organic matter

Local/regional

10-3 to 10-1

Plankton

Trophic transfer of energy and nutrients

Local/regional

100 to 101

Water column and/or sediments, small streams

Provision of habitat

Local

102 to 104

Lakes, rivers, bays

Fish and plant production

Local/regional

≥105

Ocean basins, major rivers, and lakes

Nutrient regulation, CO2 regulation

Global

 

SOURCE: Adapted from Limburg et al. (2002).

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

target scale. This is a particularly difficult problem since it is assumed to exist and yet can be managed only by comprehensive knowledge of the system under study.

The uncertainties associated with consideration of scale in assessment of ecosystem goods and services will only be resolved by continuing investigation of natural systems. At present the practical solution is upfront recognition of the potential for aggregation errors and careful framing of the assessment question. Explicit identification of the ecosystem goods and services being evaluated, careful definition of the scale at which those services are generally realized, and comparison to the scale of the assessment being undertaken can at least bound the valuation process and inform subsequent decisions.

System Dynamics

Natural systems are increasingly understood as dynamic constructs that may exist in a number of alternate states (also referred to as “regimes” or “domains of ecological attraction” depending on the terminology being used). A system may move, or “flip,” from one state to another if it passes a threshold of some controlling variable. The transition to an alternate state may be rapid or gradual, and may or may not reflect a change in the trajectory of the system. The concept of alternative states with boundary thresholds is used to explain the nonlinear behavior of natural systems. Indeed, examples of thresholds and regime shifts in aquatic ecosystems have been a significant part of the evolving understanding of nonlinear ecosystem behavior (Muradian, 2001; Scheffer and Carpenter, 2003; Scheffer et al., 2001; Walker and Meyers, 2004).

Many ecosystems can persist in a particular state or regime for some time because they exhibit resistance or resilience. Resistance is measured by the capacity to withstand disturbance without significant change, while resilience is indicated by the capacity to return to the original state after perturbation toward an alternate state. Resilience was originally described by Holling (1978) and persists as an important concept in the analysis of social-ecological system dynamics today (Walker and Myers, 2004; Walker et al. 2004).

The nonlinear system behavior that emerges in response to thresholds and regime shifts can be problematic for assessment of ecosystem services. Recognition of the points at which alternative behavior will emerge is difficult in many systems. (See Figure 3-1 for a conceptual representation of the nonlinear ecosystem response to stress.) As noted by Chavas (2000) “…ecosystem dynamics can be highly nonlinear, meaning that knowing the path of a system in some particular situation may not tell us much about its behavior under alternative scenarios.”

An example of this type of behavior can be found in the waste assimilation and transport services of lakes, rivers, and estuaries. Increased nutrient loads in an aquatic ecosystem may simply increase productivity of the resident biota up to the point of harmful eutrophication. At that point, the high levels of primary

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

FIGURE 3-1 Value responses to stress under marginal (well-behaved dynamics) and nonmarginal (nonlinear, threshold dynamics) system behaviors. SOURCE: Reprinted, with permission, from Limburg et al. (2002) © 2000 by Elsevier.

production overwhelm secondary production and decomposition processes, resulting in excessive accumulation of organic matter, depletion of oxygen in the water column, and a change in the trophic structure. The change can represent a new and undesirable condition that may persist even if nutrient loads are reduced (see Carpenter, 2003; Carpenter et al., 1998). From the perspective of ecosystem service assessment, waste assimilation may still be occurring, but habitat services, recreational services, and maintenance of biodiversity may all be significantly changed. The point at which this abrupt shift in services occurs may be controversial and unpredictable.

In some circumstances the abrupt shift, or flip to an alternate regime in state may be part of a hysteretic system behavior. In this case the stress threshold that generated the response may be significantly higher than the stress threshold that will allow a recovery. This type of response can be found in many dense and highly productive aquatic communities, such as seagrass beds (Batuik et al., 2000). Often these communities can tolerate significant levels of physical stress simply because there are a sufficient number of individuals to moderate physical conditions inside the community and enough reproductive potential to offset the

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

continual losses. When the physical stresses surpass a community’s capacity to withstand them, reestablishment can often succeed only in conditions significantly less stressful than the robust community could tolerate (Molles, 2002). In essence, the recovery threshold differs from the impact threshold such that the state of the system will lag in response to changes in controlling forces.

Cascading effects are another example of ecosystem dynamics that can be difficult to predict (Molles, 2002). Harvest of top-level predators can result in increases in lower-level predators, decreases in herbivore prey, and resultant changes in vegetation. Alterations in river flows can change the timing of nutrient introductions to downstream waterbodies, resulting in modified phytoplankton and zooplankton communities, and culminating in shifts in habitat quality for higher-trophic-level fish communities.

There is considerable ongoing research to define thresholds and develop indicators of system condition that will assess proximity of thresholds. While understanding of these system dynamics continues to expand, this knowledge can inform assessment of ecosystem functions only if the assessment occurs at appropriate spatial and temporal scales, and appropriate spatial and temporal scales can be identified only if the dynamics are already understood. In the face of this apparent conundrum the practical solution to the need to complete an assessment of ecosystem function and/or provision of services is to proceed with caution. Observations of a system’s behavior through time are an obvious first step, but such monitoring data can only confirm the existence of nonlinear behavior, not prove its absence. Simply considering the possibilities for threshold responses may be adequate to inform some assessments, and is certainly preferable to ignoring the issue.

Intrinsic Values

Many people believe that ecosystems have value quite apart from any human interest in explicit goods or services (see Chapter 2 for further information). The fact that ecosystems exhibit emergent behaviors and operate to sustain themselves is sufficient to argue that they have value to their components. Although comprehending this intrinsic value does not trouble most individuals, assessing it is problematic. Farber et al. (2002) state, “As humans are only one of many species in an ecosystem, the values they place on ecosystem functions, structures and processes may differ significantly from the values of those ecosystem characteristics to species or the maintenance (health) of the ecosystem itself.”

Incomplete Knowledge

Comprehensive valuation of aquatic ecosystems should be viewed as a practical improbability. The assumption that our knowledge is imperfect is at

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

the root of the concern for aggregation of assessments to larger scales and composite valuation of whole ecosystems. As a consequence, unforeseen behaviors and services are anticipated, and valuations are automatically caveated with concern for the state of the science. This does not imply no ecosystem valuation can be accomplished, simply that comprehensive valuation should not be presumed. Many decisions using economic or other valuation techniques can be made without a comprehensive assessment of ecosystem goods and services

An example of how the state of our understanding can impact the capacity to value an ecosystem service involves the relationship between biodiversity and aquatic ecosystem functions. In efforts to identify ecosystem services, researchers typically acknowledge the importance of habitat functions for maintenance of biodiversity. For some time, high biodiversity was assumed to confer some inherent resistance and/or resilience to a system, allowing it to sustain performance of other valued services in the face of disturbance. However, researchers are not of a single mind about the nature of the relationship between biodiversity and ecosystem functioning (e.g., Duarte, 2000; Ghilarov, 2000; Hulot et al., 2000; Schwartz et al., 2000; Ulanowicz, 1996). It can be difficult, if not impossible, therefore to accurately assess the importance of any particular ecosystem’s contribution to maintenance of biodiversity, or conversely the role of biodiversity in the functioning of the ecosystem.

Another area in which a lack of comprehensive knowledge limits full recognition of services provided by aquatic ecosystems is the continual growth in the number of ways humans can use aquatic resources. The continually expanding lists of medicinal and industrial products found in aquatic ecosystems provide obvious examples, while the evolving number of aquatic recreational activities is another. The point is that the list of services is not determined entirely by the suite of natural functions in aquatic ecosystems, but also by human ingenuity in deriving benefits.

SUMMARY: CONCLUSIONS AND RECOMMENDATIONS

In review and discussion of the state of the science in the identification of aquatic ecosystem functions and their linkage to goods and services, the committee arrived at several specific conclusions:

  • Ecologists understand the uncertainties in ecosystem analysis and accept them as inherent caveats in all discussions of system performance.

  • As the committee pursued its charge, the problems of developing an interdisciplinary terminology and/or a universally applicable protocol for valuing aquatic ecosystems were illuminated, but ultimately identified as unnecessary objectives.

  • From an ecological perspective, the value of specific ecosystem functions/services is entirely relative. The spatial and temporal scales of analysis are critical determinants of potential value.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
  • Potentially useful classification and inventories of aquatic ecosystems as well as their functional condition exist at both regional and national levels, though the relevance of these classification and inventory systems to assessing and valuing aquatic ecosystems is not always clear.

  • Ecologists have qualitatively described the structure and function of most types of aquatic ecosystems. However, the complexity of ecosystems remains a barrier to quantification of these features, particularly their interrelationships.

  • General concepts regarding the linkages between ecosystem function and services have been developed. Although precise quantification of these relationships remains elusive, the general concepts seem to offer sufficient guidance for valuation to proceed with careful attention to the limitations of any ecosystem assessment.

  • Many, but not all, of the goods and services provided by aquatic ecosystems are recognized by both ecologists and economists. These goods and services can be classified according to their spatial and temporal importance.

  • Complex ecosystem dynamics and incomplete knowledge of ecosystems will have to be resolved before comprehensive valuation of ecosystems is tractable, but comprehensive ecosystem valuation is not generally essential to inform many management decisions.

  • Further integration of the sciences of economics and ecology at both intellectual and practical scales will improve ecologists’ ability to provide useful information for assessing and valuing aquatic ecosystems.

There remains a significant amount of research and work to be done in the ongoing effort to codify the linkage between ecosystem structure and function and the provision of goods and services for subsequent valuation. The complexity, variability, and dynamic nature of aquatic ecosystems make it likely that a comprehensive identification of all functions and derived services may never be achieved. Nevertheless, comprehensive information is not generally necessary to inform management decisions. Despite this unresolved state, future ecosystem valuation efforts can be improved through use of several general guidelines and research conducted in the following areas:

  • Aquatic ecosystems generally have some capacity to provide consumable resources (e.g., water, food); habitat for plants and animals; regulation of the environment (e.g., hydrologic cycles, nutrient cycles, climate, waste accumulation); and support for nonconsumptive uses (e.g., recreation, aesthetics, research). Considerable work remains to be done in documentation of the potential that various aquatic ecosystems have for contribution in each of these broad areas.

  • Delivery of ecosystem goods and services occurs in both space and time. Local and short-term services may be most easily observed and documented, but the less intuitive accumulation of services over larger areas and time

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

intervals may also be significant. Alternatively, services that are significant only when performed over large areas or long time intervals may be beyond the capacity of some ecosystems. Investigation of the spatial and temporal thresholds of significance for various ecosystem services is necessary to inform valuation efforts.

  • Natural systems are dynamic and frequently exhibit nonlinear behavior. For this reason, caution should be used in extrapolation of measurements in both space and time. Although it is not possible to avoid all mistakes in extrapolation, the uncertainty warrants explicit acknowledgment. Methods are needed to assess and articulate this uncertainty as part of system valuations.

REFERENCES

Batuik, R.A., P. Bergstrom, M. Kemp, E. Koch, L. Murray, J.C. Stevenson, R. Bartleson, V. Carter, N.B. Rybicki, J.M. Landwehr, C. Gallegos, L. Karrh, M. Naylor, D. Wilcox, K.A. Moore, and S. Ailstock. 2000. Chesapeake Bay Submerged Aquatic Vegetation Water Quality and Habitat-Based Requirements and Restoration Targets: A second technical synthesis. Annapolis, Md.: U.S. Environmental Protection Agency, Chesapeake Bay Program.

Berkes, F., J. Colding, and C. Folke (eds.). 2003. Navigating Social-Ecological Systems: Building Resiliency for Complexity and Change. Cambridge, U.K.: Cambridge University Press. Bowles, D.E., and T.L. Arsuffi. 1993. Karst aquatic ecosystems of the Edwards Plateau region of central Texas, USA—A consideration of their importance, threats to their existence, and efforts for their conservation. Aquatic Conservation-Marine and Freshwater Ecosystems 3:317-329.

Brinson, M.M. 1993. A Hydrogeomorphic Classification for Wetlands. U.S. Army Corps of Engineers, Wetlands Research Program Technical Report WRP-DE-4. Vicksburg, Miss.: U.S. Corps of Engineers.

Busch, W.D.N., and P.G. Sly. 1997. The Development of an Aquatic Habitat Classification System for Lakes. Boca Raton, Fla.: CRC Press.


Carpenter, S.R. 2003. Regime Shifts in Lake Ecosystems: Pattern and Variation. Book 15 in the Excellence in Ecology Series. Ecology Institute: Olendorf/Luhe, Germany.

Carpenter, S., N. Caraco, D.L. Correll, R.W. Howarth, A.N. Sharpley, and V.H. Smith. 1998. Nonpoint pollution of surface waters with phosphorus and nitrogen. Ecological Applications 8:559-568.

Chang, C., and R.C. Griffin. 1992. Water marketing as a reallocative institution in Texas. Water Resources Research 28:879-890.

Chavas, J. 2000. Ecosystem valuation under uncertainty and irreversibility. Ecosystems 3:11-15.

Chen, C.C., D. Gillig, and B.A. McCarl. 2001. Effects of climatic change over a water dependent regional economy: A study of the Texas Edwards Aquifer. Climatic Change 49:397-409.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. FWS/OBS-79/31. Corvallis, Ore.: U.S. Fish and Wildlife Service.

Crowe J.C., and J. M. Sharp, Jr. 1997. Hydrogeologic delineation of habitats for endangered species—The Comal Springs/River system: Berlin. Environmental

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Geology 30(1-2): 17-33.

Culver, D.C., L.L. Master, M.C. Christman, and H.H. Hobbs. 2000. Obligate cave fauna of the 48 continuous United States. Conservation Biology 14:386-401.

Custodio, E. 2002. Aquifer over-exploitation: What does it mean? Hydrogeology Journal 10: 254-277.


Dahl, T.E. 2000. Status and Trends of Wetlands in the Conterminous United States 1986 to 1997. Washington, D.C.: U.S. Department of the Interior, Fish and Wildlife Service.

Daily, G.C. 1997. Introduction: What are ecosystem services? Pp. 1-10 in Nature’s Services: Societal Dependence on Natural Ecosystems, G.C. Daily (ed.). Washington, D.C.: Island Press.

De Groot, R.S., M.A. Wilson, and R.M.J. Boumans. 2002. A typology for the classification, description and valuation of ecosystem functions, goods and services. Ecological Economics 41:393-408.

Duarte, C.M. 2000. Marine biodiversity and ecosystem services: An elusive link. Journal of Experimental Marine Biology and Ecology 250(1-2):117-131.


Edwards, R.J., G. Longley, R. Moss, J. Ward, R. Matthews, and B. Stewart. 1989. A classification of Texas aquatic communities with special consideration toward the conservation of endangered and threatened taxa. Texas Journal of Science 41:231-240.

EPA (U.S. Environmental Protection Agency). 2001. National Coastal Condition Report. EPA-620/R-01/005. Washington, D.C.: U.S. EPA, Office of Research and Development/Office of Water. Also available on-line at http://www.epa/gov/owow/oceans/NCCR/index Accessed October 2002.

EPA. 2002. 2000 National Water Quality Inventory. EPA-841-R-2-001. Washington, D.C.: Office of Water.

Ewel, K.C. 2002. Water quality improvement by wetlands. Pp. 329-344 in Nature’s Services: Societal Dependence on Natural Ecosystems, G.C. Daily (ed.). Washington, D.C.: Island Press.


Farber, S.C., R. Costanza, and M.A. Wilson. 2002. Economic and ecological concepts for valuing ecosystem services. Ecological Economics 41:375-392.


Ghilarov, A.M. 2000. Ecosystem functioning and intrinsic value of biodiversity. Oikos 90(2): 408-412.

Gibert, J., D.L. Danielopol, and J.A. Standford (eds.). 1994. Groundwater Ecology. San Diego, Calif.: Academic Press.

Great Lakes National Program Office. 2001. Great Lakes Ecosystem Report. Chicago, Ill.: U.S. Environmental Protection Agency.

Great Lakes National Program Office. 2002. The Great Lakes: An Environmental Atlas and Resource Book. Washington, D.C.: U.S. Environmental Protection Agency.

Gunderson, L.H. and C.S. Holling (eds). 2002. Panarchy: Understanding Transformations in Human and Natural Systems. Washington, D.C.: Island Press.

Gunderson, L.H. and L. Pritchard, Jr. (eds). 2002. Resilience and the Behavior of Large Scale Systems. Washington, D.C.: Island Press.


Holling, C.S. (ed.). 1978. Adaptive Environmental Assessment and Management. New York: John Wiley and Sons.

Hulot, F.D., G. Lacroix, F. Lescher-Moutoue, and M. Loreau. 2000. Functional diversity governs ecosystem response to nutrient enrichment. Nature (London) 405(6784): 340-344.


Jones, J.B., and P.J. Mulholland (eds.). 2000. Streams and Ground Waters. San Diego, Calif.: Academic Press.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Junk, W.J., P.B. Bayley, and R.E. Sparks. 1989. The flood pulse concept in river-floodplain systems. In Proceedings International Large River Symposium (LARS), C.P. Dodge (ed.). Canadian Special Publication in Fisheries and Aquatic Sciences 106:110-127.


Kaiser, R.A., and L.M. Phillips. 1998. Dividing the waters: Water marketing as a conflict resolution strategy in the Edwards Aquifer region. Natural Resources Journal 38:411-444.

Keplinger, K.O., and B.A. McCarl. 2000. An evaluation of the 1997 Edwards Aquifer irrigation suspension. Journal of the American Water Resources Association 36:889-901.

Keplinger, K.O., B.A. McCarl, M.E. Chowdhury, and R.D. Lacewell. 1998. Economic and hydrologic implications of suspending irrigation in dry years. Journal of Agricultural and Resource Economics 23:191-205.

Knutson, M.G., J.R. Sauer, D.A. Olsen, M.J. Mossman, L.M. Hemensath, and M.J. Lannoo. 1999. Effects of landscape composition and wetland fragmentation on frog and toad abundance and species richness in Iowa and Wisconsin, U.S.A. Conservation Biology 13(6):1437-1446.


Limburg, K.E., R.V. O’Neill, R. Costanza, and S. Farber. 2002. Complex systems and valuation. Ecological Economics 41:409-420.

Longley, G. 1986. The biota of the Edwards aquifer and the implications for paleozoogeography. Pp. 51-54 in The Balcones Escarpment, Central Texas, P.L. Abbott and C.M. Woodruff, Jr. (eds.). Boulder, Colo.: Geological Society of America.

Lord, L.A. 1993. Guide to Florida Environmental Issues and Information. Winter Park, Fla.: Florida Conservation Foundation.


Maxwell, J.R., C.J. Edwards, M.E. Jensen, S.J. Paustian, J. Parrot, and D.M. Hill. 1995. A Hierarchical Framework of Aquatic Ecological Units in North America. GTRNC-176. St. Paul, Minn.: U.S. Department of Agriculture, Forest Service, North Central Forestry Experimental Station.

McCarl, B.A., C.R. Dillon, K.O. Keplinger, and R.L. Williams. 1999. Limiting pumping from the Edwards Aquifer: An economic investigation of proposals, water markets, and spring flow guarantees. Water Resources Research 35:1257-1268.

MEA (Millenium Ecosystem Assessment). 2003. Ecosystems and Human Well-being: A Framework for Assessment. Washington, D.C.: Island Press.

Molles, M.C. Jr. 2002. Ecology: Concepts and Applications. New York: McGraw Hill.

Muradian, R. 2001. Ecological thresholds: A survey. Ecological Economics 38:7-24.


NRC (National Research Council). 2002a. Florida Bay Research Program and Their Relation to the Comprehensive Everglades Restoration Plan. Washington, D.C.: National Academy Press.

NRC. 2002b. The Missouri River Ecosystem: Exploring Prospects for Recovery. Washington, D.C.: National Academy Press.

NRC. 2003. Adaptive Monitoring and Assessment of the Comprehensive Everglades Restoration Plan. Washington, D.C.: The National Academies Press.


Odum, E.P. 1993. Ecology and Our Endangered Life-Support Systems. Second Edition. Sunderland, Mass.: Sinauer Associates Incorporated.

Odum, E.P., and M.G. Turner. 1990. The Georgia landscape: A changing resource. Pp. 131-163 in Changing Landscapes: An Ecological Perspective, I.S. Zonnevald and R.T.T. Forman (eds.), New York: Springer-Verlag.

Odum, H.T. 1988. Self-organization, transformity, and information. Science 242:1132-1139.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Odum, H.T. 1996. Environmental Accounting: Energy and Environmental Decision-Making. New York: John Wiley.

Odum, H.T., and E.P. Odum. 2000. The energetic basis for valuation of ecosystem services. Ecosystems 3:21-23.


Peterson, C.H., and J. Lubchenco. 2002. Marine ecosystem services. Pp. 177-194 in Nature’s Services: Societal Dependence on Natural Ecosystems, G.C. Daily (ed.). Washington, D.C.: Island Press.

Postel, S.L., and S. Carpenter. 1997. Freshwater ecosystem service. Pp. 195-214 in Nature’s Services: Societal Dependence on Natural Ecosystems, G.C. Daily (ed.). Washington, D.C.: Island Press.

Purdum, E.D. 2002. Florida Waters: A Water Resources Manual from Florida’s Water Management Districts. Orlando, Fla.: Institute of Science and Public Affairs, Florida State University for Florida’s Water Management Districts.


Rosgen, D.L. 1994. A classification of natural rivers. Catena 22:169-199.


Schaible, G.D., B.A. McCarl, and R.D. Lacewell. 1999. The Edwards Aquifer water resource conflict: USDA farm program resource-use incentives? Water Resources Research 35: 3171-3183.

Scheffer, M., and S.R. Carpenter. 2003. Catastrophic regime shifts in ecosystems: Linking theory to observation. Trends in Ecology and Evolution 18(12):648-656.

Scheffer, M., S. Carpenter, J.S. Foley, C. Folke, and B. Walker. 2001. Catastrophic shifts in ecosystems. Nature 413:591-596.

Schwartz, M.W., C.A. Brigham, J.D. Hoeksema, K.G. Lyons, M.H. Mills, and P.J. van-Mantgem. 2000. Linking biodiversity to ecosystem function: Implications for conservation ecology. Oecologia 122(3):297-305.

Scientific and Technical Advisory Committee. 2003. Chesapeake Futures: Choices for the 21st Century. STAC Publication Number 03-001. Edgewater, Md.: CRC, Inc.

Smith, R.D., A. Ammann, C. Bartoldus, and M.M. Brinson. 1995. An Approach for Assessing Wetland Functions Using Hydrogeomorphic Classification, Reference Wetlands, and Functional Indices. Technical Report WRP-DE-9. Vicksburg, Miss.: U.S. Army Engineer Waterways Experiment Station.

Sousa, P.J. 1985. Habitat Suitability Index Models: Red-Spotted Newt. Biological Report 82 (10.111). Washington, D.C.: U.S. Fish and Wildlife Service

Stanford, J. S., J.V. Ward, W.J. Liss, C.A. Frissell, R.N. Williams, J.A. Lichatowich, and C.C. Coutant. 1996. A general protocol for restoration of regulated rivers. Regulated Rivers: Research and Management 12:391-413.


TNC (The Nature Conservancy). 1997. A classification framework for freshwater communities. In Proceedings of the Nature Conservancy’s Aquatic Community Classification Workshop. Chicago, Ill.: TNC, Great Lakes Program Office.

Turner, M.G., E.P. Odum, R. Constanza, and T.M. Springer. 1988. Market and nonmarket values of the Georgia landscape. Environmental Management 12(2):209-217.


Ulanowicz, R.E. 1996. The propensities of evolving systems. In Social and Natural Complexity, Khalil, E.L., K.E. Boulding (eds.). London: Routledge.

USDA (U.S. Department of Agriculture-Natural Resources Conservation Services). 2000. Summary Report of the 1997 National Resources Inventory. Washington, D.C.: Iowa State University Statistical Laboratory and USDA Natural Resources Conservation Services.


Vannote, R.L., G.W. Minshall, J.R. Cummins, J.R. Sedell, and C.E. Cushing. 1980. The river continuum concept. Canadian Journal of Fisheries and Aquatic Sciences 37:130-137.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×

Walker, B., C. S. Holling, S.R. Carpenter, and A. Kinzig. 2004. Resilience, adaptability and transformability in social-ecological systems. Ecology and Society 9(2):5. Available on-line at http://www.ecologyandsociety.org/vol9/iss2/art5.

Walker, B. and J.A. Meyers. 2004. Thresholds in ecological and social-ecological systems: A developing database. Ecology and Society 9(2):3. Available on-line at: http://www.ecologyandsociety.org/vol9/iss2/art3.

Wass, M.L., and T.D. Wright. 1969. Coastal Wetlands of Virginia. Special Report in Applied Marine Science. Gloucester Point, Va.: Virginia Institute of Marine Science.

Wetzel, R.G. 2001. Freshwater and wetland ecology: challenges and future frontiers. In Sustainability of Wetlands and Water Resources: Achieving Sustainable Systems in the 21dst Century, M.M. Holland, E. Blodd, and L. Shaffer (eds.). Covelo, Calif.: Island Press.

Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 59
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 60
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 61
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 62
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 63
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 64
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 65
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 66
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 67
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 68
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 69
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 70
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 71
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 72
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 73
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 74
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 75
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 76
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 77
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 78
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 79
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 80
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 81
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 82
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 83
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 84
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 85
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 86
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 87
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 88
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 89
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 90
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 91
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 92
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 93
Suggested Citation:"3 Aquatic and Related Terrestrial Ecosystems." National Research Council. 2005. Valuing Ecosystem Services: Toward Better Environmental Decision-Making. Washington, DC: The National Academies Press. doi: 10.17226/11139.
×
Page 94
Next: 4 Methods of Nonmarket Valuation »
Valuing Ecosystem Services: Toward Better Environmental Decision-Making Get This Book
×
Buy Paperback | $55.00 Buy Ebook | $43.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Nutrient recycling, habitat for plants and animals, flood control, and water supply are among the many beneficial services provided by aquatic ecosystems. In making decisions about human activities, such as draining a wetland for a housing development, it is essential to consider both the value of the development and the value of the ecosystem services that could be lost. Despite a growing recognition of the importance of ecosystem services, their value is often overlooked in environmental decision-making. This report identifies methods for assigning economic value to ecosystem services—even intangible ones—and calls for greater collaboration between ecologists and economists in such efforts.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!