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The Law and Policy of Ecosystem Services
By J.B. Ruhl, Steven E. Kraft, Christopher L. Lant ISLAND PRESS
Copyright © 2007 Island Press
All rights reserved.
ISBN: 978-1-59726-769-4
CHAPTER 1
Ecology
It is tempting to overstate the case for ecosystem services, to try to find them everywhere simply because anywhere is in one or another ecosystem. But it is important not to confuse ecosystem functions, which are ubiquitous, with ecosystem services, which are the consequence of only some ecosystem functions. The critical difference between the two, and which makes the development of ecosystem services policy both complicated and controversial, is that ecosystem services have relevance only to the extent human populations benefit from them. They are purely anthropocentric. The ecology of ecosystem services, therefore, must be carefully defined in order to begin considering how to formulate a policy foundation for their management.
Ecosystems and Ecosystem Processes
Since Tansley's (1935) early description of the ecosystem as part of a continuum of physical systems in nature, decades of research and literature have been devoted to forging the concept into a scientific discipline (Brooks et al. 2002; Golley 1993). Modern ecologists describe ecosystems as the complex of organisms that appear together in a given area and their associated abiotic environment, all interacting through the flow of energy to build biotic structure and materials cycles (Blair et al. 2000; Millennium Ecosystem Assessment 2005). Ecosystems thus move and transform energy and materials through basic processes such as those listed by Virginia and Wall (2001):
Photosynthesis
Plant nutrient uptake
Microbial respiration
Nitrification and denitrification
Plant transpiration
Root activity
Mineral weathering
Vegetation succession
Predator–prey interactions
Decomposition
These and other ecosystem processes operate according to fundamental internal rules and constraints of physical and biotic systems. Energy transformation processes are essentially one-way flows, preventing reuse or recycling of the energy units. But nutrients can circulate through different components of an ecosystem, leading to what ecologists call nutrient cycles and nutrient pools. At its most fundamental level, ecology as a discipline is interested in describing and quantifying the factors that regulate energy transformation and nutrient cycling within an ecosystem as defined. And because these processes operate at many scales, ecological studies also take place at many scales. For example, photosynthesis can be measured and studied at scales ranging from the individual cell to the canopy of a forest ecosystem as defined. Often, therefore, it is as much a question of how to define an ecosystem as it is to understand how these processes work within it.
Ecosystem Functions
The process-based description of ecosystems has led to improved understanding of the functions ecosystems perform in natural settings. The transformation of energy and materials into vegetation structure, for example, provides habitat for other organisms. The decomposition of materials in the ecosystem builds soil structure. Each process under way in an ecosystem thus contributes to one or more of a set of functions associated with the ecosystem and with its relation to other ecosystems (Virginia and Wall 2001).
The same basic biological and chemical processes occur in all ecosystems, but different conditions yield different functional representations (Blair et al. 2000). It is like electronic circuitry—the same principles of electromagnetism apply in all cases, but different combinations of circuitry and voltage produce different functional applications. An inventory of just some of the functions typically associated with different ecosystem processes, and which we should expect to observe in different forms and magnitudes across ecosystems is provided in Table 1.1.
As this representation suggests, there is no one-to-one correspondence between ecosystem processes and ecosystem functions. In reality, many processes are needed to produce any of the defined functions. For example, a farm, which can be thought of as a highly modified and highly managed ecosystem, relies on biotic production, energy flow, decomposition, and nutri-ent cycling to make possible its basic function of producing, say, corn. It is no different in the remote undisturbed depths of a rain forest. Hence, another key study theme of ecology is to improve our understanding of how the basic ecosystem processes work together to generate the functions vital to sustaining the ecosystem within its environment.
Ecosystem Structure and Natural Capital
Ecosystem functions contribute to the building of the ecosystem's physical structure, such as biomass (e.g., vegetation and wildlife) and abiotic resources (e.g., soil and water), which in turn supports the sustainability of the functions (Christensen et al. 1996; Daly and Farley 2003). Events that degrade ecosystem structure (e.g., overfishing in coral reef ecosystems) consequently disrupt the integrity of the associated ecosystem functions (Roberts 1995). These effects are important not only to the sustainability of the ecosystem but also to the sustainability of humans, given the importance of ecosystems to human well-being (Millennium Ecosystem Assessment 2003, 2005). This property—that ecosystem structure and functions provide for human needs and wants—is what makes ecology inevitably relevant to economics.
Ecologists thus analogize ecosystem structure to capital as that term is used in economic theory—the stock that possesses the capacity of giving rise to the flow of goods and services (Costanza et al. 1997; Ekins et al. 2003). Ecological capital, or "natural capital" as many ecological economists call it, consists of the ecosystem structure and functions that support the creation and flow of goods and services valuable to humans (Clark 1995; Costanza and Daly 1992; Daily and Dasgupta 2001). Other than in a totally artificial environment, such as a space station, "zero natural capital implies zero human welfare because it is not feasible to substitute, in total, purely 'non-natural' capital for natural capital" (Costanza et al. 1997, 255). Yet, as with economic capital, we need not reach zero before we feel the effects of depreciating stock. As Daly and Farley summarize,
[T]he structural elements of an ecosystem are stocks of biotic and abiotic resources (minerals, water, trees, other plants and animals), which when combined together generate ecosystem functions, or services. The use of a biological stock at a nonsustainable level in general also depletes a corresponding fund and the services it provides. Hence, when we harvest trees from a forest, we are not merely changing the capacity of the forest to create more trees, but are also changing the capacity of the forest to create more ecosystem services, many of which are vital to our survival. (2003, 106–107)
Another theme of ecology, therefore, is focused on understanding the impact of natural and anthropogenic events on the investment in and depreciation of natural capital in the form of ecosystem structure, and the consequent impact on the delivery of goods and services from the ecosystem (Deutsch et al. 2003; Ekins 2003; Ekins et al. 2003). Like our conventional economy, however, understanding cause and effect in the ecological economy is a horribly complicated undertaking given the complexity of the subject matter.
Ecosystems as Complex Adaptive Systems
The dynamic interactions of ecosystem processes, functions, and structural components have led many ecologists to describe ecosystems through the terms used in complex adaptive systems theory (Limburg et al. 2002), which provides a useful way of thinking about the difficulty of managing ecosystem services. Complex adaptive systems theory explores the behavior and properties of diverse, interconnected, autonomous agents (Holland 1995; Kauffman 1995). Systems composed of such agents—from immune systems to economies—are seen in physical, biological, or social contexts to generate feedback and feedforward loops among agents, through which the action of any one agent could affect many others, including the original actor. The aggregation of these feedback and feedforward loops produces the emergent behavior of dissipative system structure, which will inevitably exhibit dynamic nonlinear properties not found in or predictable from observation of any single agent in the system. Indeed, complex adaptive systems research focuses on the ways in which this emergent system behavior provides sustainability for the system as a whole by facilitating adaptation to external disturbances. On the other hand, the price of this adaptive capacity is constant change—a form of stable disequilibrium balanced between order and chaos (Kauffman 1995). Costanza sums up the difficulties of studying such systems:
"Complex systems" are characterized by: (1) strong (usually nonlinear) interactions among the parts; (2) complex feedback loops that make it difficult to distinguish cause from effect; (3) significant time and space lags; discontinuities, thresholds and limits, all resulting in (4) the inability to simply "add up" or aggregate small-scale behavior to arrive at large-scale results. (1996, 981)
It is no surprise that ecology has embraced complex adaptive systems theory for, as Simon Levin (1998, 431) has claimed, ecosystems are "prototypical examples of complex adaptive systems." Certainly the basic quality of complex systems exists in ecosystem dynamics, in that "we cannot understand ecosystems only by considering their separate components" (Bailey 1996, 16). John Holland, one of the leading figures in complex systems research, has explained the reasons why:
Ecosystems are continually in flux and exhibit a wondrous panoply of interactions such as mutualism, parasitism, biological arms races, and mimicry.... Matter, energy, and information are shunted around in complex cycles. Once again, the whole is more than the sum of its parts. Even when we have a catalogue of the activities of most of the participating species, we are far from understanding the effect of changes in the ecosystem. (1995, 3)
Indeed, though perhaps misunderstanding the adaptive energy supplied by ecosystem diversity and its emergent system behavior, Tansley (1935) claimed that "the gradual attainment of more complete dynamic equilibrium ... is the fundamental characteristic" of ecosystems, and that "the order of stability of all of the chemical elements is of course immensely higher than that of an ecosystem, which consists of components that are themselves more or less unstable—climate, soil, and organisms." But Tansley, like his counterparts, believed that equilibrium was "perfect," and that "its degree of perfection is measured by its stability" (301). Over time, however, the diversity–stability dimensions of ecosystem properties became increasingly appreciated (Pimm 1984; Tilman 1999), focusing research on the properties that bring dynamic, nonlinear disequilibrium to the table for ecosystems, and improving our understanding that complexity and diversity in ecosystems are, in fact, the properties most important to sustainability, but also the most vulnerable to human interference (Abel and Stepp 2003; Hartvigsen et al. 1998; Holling et al. 2002; Levin 1999; Limburg et al. 2002; Milne 1998).
Thus, ecologists today engage in complex systems-based research into such matters as soil–microbe dynamics (Young and Crawford 2004), linkages between aboveground and belowground biota (Wardle et al. 2004), the effects of disturbance events on forest structure outcomes (Savage et al. 2000), plant–plant interactions in response to environmental stress (Brooker 2006), mutualistic relations between plants and their pollinators (Bascompte et al. 2006), and the causes of "flips" in coral reef species assemblages (Moberg and Folke 1999). As such research unfolds, ecologists routinely account for two properties as the central products of complex adaptive system dynamics in operation: resistance—the ability of an ecosystem to withstand external stress without loss of function; and resilience—the ability of the ecosystem to recover from disturbance (Allison and Hobbs 2004; Carpenter and Brock 2004; Christensen et al. 1996; Folke et al. 1996; Holling 1996; Holling and Gunderson 2002; Tilman 1999; Virginia and Wall 2001; Walker et al. 2006). As Limburg and her colleagues explain,
Complex, interactive systems tend to converge on stable states, or dynamic equilibria, in which flows and processes are balanced. To that end, they evolve stabilizing mechanisms. In ecological systems this propensity toward stability is measured by two emergent properties, resistance and resilience. Resistance measures how unyielding a system is to a disturbance and resilience measures how quickly a disturbed system returns to its equilibrium. (2002, 410)
Nevertheless, the more that is learned about these properties, the more researchers such as Christensen et al. (1996) appreciate that "[w]ith complexity comes uncertainty.... [W]e must recognize that there will always be limits to the precision of our predictions set by the complex nature of ecosystem interactions" (669). Add to this the nature of political and social institutions involved in ecosystem management as themselves exceedingly complex systems (Janssen 2002; Walker et al. 2006), and the problem of devising ecosystem services policies becomes all the more daunting.
Ecosystem Boundaries
The model of ecosystems as complex adaptive systems brimming with dynamic properties and unpredictable outcomes thus complicates one of the most fundamental starting points for ecosystem research and management—where do these complex entities begin and end? Tansley borrowed the "system" in ecosystem from physics, and in the strictest physical sense a system has boundaries that delimit it from its surroundings. But no ecosystem is perfectly delimited, or closed, in this respect (Bailey 1996). Wherever we might draw the physical "boundary" of an ecosystem for political, research, or other purposes, inputs of energy (e.g., sunlight) and materials (e.g., water) from outside its bounds will affect internal processes, and outputs of energy (e.g., increased water temperature) and materials (e.g., decomposition waste) will be returned to the producing ecosystem or become inputs delivered for use in other ecosystems (Blair et al. 2000). Moberg and Folke (1999), for example, document the intricate linkages of energy and materials that exist between mangrove forests, sea grass beds, and coral reefs, three discrete ecosystems found in tropical seascape regimes, and Holmlund and Hammer (1999) do the same in their study of the contri-bution of fish to ecosystem services in the interface between terrestrial, aerial, and aquatic ecosystems. Countless other examples abound. Ecosystem processes, in other words, receive at least some energy and materials from outside, use energy to transform and recycle materials internally, thereby building ecosystem structure, and then move at least some energy and materials back to the outside. An inventory of just some of the possible external inputs, internal uses, and external outputs that are enabled and supported by ecosystem processes might include those shown in Table 1.2.
The "open" nature of ecosystems under this process-based conception presents difficult questions of boundary definition for research and management purposes (Ruhl 1999). Indeed, some commentators have gone so far as to argue that any effort to forge ecosystem-based policies is premature because we do not know enough about the biological and physical boundaries of ecosystems and thus cannot possibly develop effective policy (Fitzsimmons 1999). But this position seems calculated to preclude us from ever developing an ecosystem protection policy, for it will never be scientifically accurate to speak of an exact ecosystem "boundary." On the other hand, some commentators suggest that ecosystem boundaries be defined by a highly fluid set of criteria that would in theory allow tailor-made ecosystems based on ecological, economic, social, spatial, and temporal factors (Keystone Center 1996). Under that approach anything would qualify as an ecosystem depending on who is asked; little consistency of definition over time and space could be expected.
(Continues...)
Excerpted from The Law and Policy of Ecosystem Services by J.B. Ruhl, Steven E. Kraft, Christopher L. Lant. Copyright © 2007 Island Press. Excerpted by permission of ISLAND PRESS.
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