The Emergence Of New Ecosystems

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A central theme of this book has been the development of the concept that new ecosystems can be designed, constructed, and operated for the benefit of humanity through ecological engineering. The concept of new ecosystems was introduced in Chapter 1 and was elaborated in subsequent chapters that focused on particular case studies. New ecosystems originate through human management, along with the self-organizational properties of living systems. The mix of engineered design with nature's self-design makes these ecosystems unique. The study of new ecosystems is often marked with surprises because they are not yet fully understood (Loucks, 1985; O'Neill and Waide, 1981). Like genetically engineered organisms, these ecosystems have never existed previously. Those who design, construct, and operate the new ecosystems are therefore exploring new possibilities of ecological structure and function. In this sense, ecological engineering is really a form of theoretical ecology. This book is an introduction to the new ecosystems that are emerging all around us through self-organization in different contexts.

Humans have been creating new ecosystems for thousands of years, but it is only in the last 30 years or so that these ecosystems have been recognized as objects for study by ecologists. Some of these ecosystems have been intentionally created while others have developed for various unintended reasons. Agriculture is probably the best example of a system that has been intentionally created. The origin of agriculture, on the order of 10,000 years ago, consisted of domesticating certain wild plants and animals and creating production systems from these species in modified natural ecosystems. Thus, plants were raised on cropland and grazing animals were raised on pastures or rangeland. Early agriculture differed little from natural ecosystems, but the modifications increased over time with greater uses of energy subsidies. Although the agricultural system is dominated by domesticated species, a variety of pest species has self-organized as part of the system. Management of agricultural land involves inputs of energy to channel production to humans and away from pests, and to reduce losses due to community respiration. In their modern forms, agricultural systems differ greatly from natural ecosystems, often with very low diversity (i.e., monocultures), large inputs of fossil fuel-based energies (i.e., mechanized tillage, fertilizers, etc.), and regular, orderly spatial patterns of component units (i.e., row crops arrangements).

The idea that agricultural systems actually were ecosystems evolved in the early 1970s. This occurred concurrently with the wide use of the ecosystem concept in the International Biological Program. Previously, ecologists almost exclusively studied natural ecosystems or their components. During this time agricultural systems themselves were studied by applied scientists with narrow focus in agronomy, entomology, or animal science. The ecosystem concept allowed ecologists to "discover" agriculture as systems of interest and for the applied scientists to expand their view to a more holistic perspective. Antecedent ecological studies of agricultural crops had been undertaken, with emphasis on primary production and energy flow (Bray, 1963; Bray et al., 1959; Gordon, 1969; Transeau, 1926), but this work had relatively little influence on the science of ecology. After the early 1970s, however, whole system studies of agriculture by ecologists became common (Cox and Atkins, 1975; Harper, 1974; Janzen, 1973; Loucks, 1977) and similar studies by the traditional agricultural scientists followed soon after. In fact, a journal named Agroecosystems was initiated in 1974 as a special outlet for ecological studies of agricultural systems. This line of research is very active with many useful contributions on nutrient cycling (Hendrix et al., 1986; Peterson and Paul, 1998; Stinner et al., 1984), conservation biology (Vandermeer and Perfecto, 1997), and the design of sustainable agroecosystems (Altieri et al., 1983; Ewel, 1986b).

Around this same time period the ecosystem concept was applied to other new systems. For example, Falk (1976, 1980) studied suburban lawn ecosystems near Washington, DC. Lawns are heavily managed ecosystems that provide aesthetic value to humans. Falk identified food chains, measured energy flows, and documented management techniques using approaches developed for natural grassland systems. This work was an in-depth study of a new ecosystem type that later was expanded on by Bormann et al. (1993). Much more significant has been research on urban ecosystems. This work began in the 1970s (Davis and Glick, 1978; Stearns and Montag, 1974) and steadily increased, especially in Europe (Bernkamm et al., 1982; Gilbert, 1989; Tangley, 1986). Urban areas include many fragments of natural habitats along with entirely new habitats (Kelcey, 1975) and have unique features as noted by Rebele (1994):

... there are some special features of urban ecosystems like mosaic phenomena, specific disturbance regimes, the processes of species invasions and extinctions, which influence the structure and dynamics of plant and animal populations, the organization and characteristics of biotic communities and the landscape pattern as well in a different manner compared with natural ecosystems. On behalf of the ongoing urbanization process, urban ecosystems should attract increasing attention by ecologists, not only to solve practical problems, but also to use the opportunity for the study of fundamental questions in ecology.

Much research is currently being carried out on urban ecosystems (Adams, 1994; Collins et al., 2000; Pickett et al., 2001; Platt et al., 1994; Rebele, 1994), including significant projects funded by the National Science Foundation at two long-term ecological research sites in Baltimore, MD, and Phoenix, AZ (Parlange, 1998). In addition, a journal named Urban Ecosystems was begun in 1996 for publishing the growing research on this special type of new system.

In a sense, then, there has been a paradigm shift in ecology since the 1970s with ecologists embracing the idea that humans have created new ecosystems. Most ecologists probably still prefer to study only natural systems, but research is established and growing on agroecosystems and urban ecosystems. This work is not necessarily considered to be applied research, though it is certainly an easy and logical connection to make. Rather, there are a number of ecologists who are studying agriculture and urban areas as straightforward examples of ecosystems. These are new systems with basic features (energy flow, nutrient cycling, patterns of species distributions, etc.) common to all ecosystems but with unique quantitative and qualitative characteristics that require study to elucidate. Ludwig (1989) called these anthropic ecosystems because of their strong human influence and proposed an ambitious program for their study.

There are many examples of new ecosystems beyond those mentioned above and throughout this book. Hedgerows, fragmented forests, brownfields, rights-of-way, and even cemeteries (Thomas and Dixon, 1973) are examples of new terrestrial systems, and there are many aquatic examples as well. H. T. Odum originally began referring to polluted marine systems as new ecosystems and developed a classification system that can be generalized to cover all ecosystem types. His ideas developed from research along the Texas coast in the late 1950s and early 1960s. This work involved ecosystem metabolism studies of natural coastal systems and those altered by human influences. The latter included brine lagoons from oil well pumping, ship channels, harbors receiving seafood industry waste discharges, and bays with multiple sources of pollution. H. T. Odum first referred to these systems as "abnormal marine ecosystems" (H. T. Odum et al., 1963), then as "new systems associated with waste flows" (H. T. Odum, 1967), and finally as "emergent new systems coupled to man's influence" (H. T. Odum and Copeland, 1972). The concept of emergent new systems is best articulated in the classification system developed for U.S. coastal systems (Copeland, 1970; H. T. Odum and Copeland, 1969, 1972). This system classified ecosystems by their energy signatures with names associated with the most prominent feature or, in other words, the one that had the greatest impact on the energy budget of the ecosystem. A whole category in this classification was given to new ecosystems (Table 9.1) with examples of all major types of human-dominated estuarine systems. This is a philosophically important conceptualization. Although H. T. Odum acknowledged that these ecosystems were "unnaturally" stressed by humans, he chose to refer to them as new systems rather than stressed systems. This distinction may at first seem subtle, but it is not. It carries with it a special notion of ecosystem organization.

The concept of new ecosystems implies that the human influence is literally a part of the system and therefore an additional feature to which organisms must adapt (Figure 9.1A). Thus, human pollution is viewed the same as natural stressors such as salt concentration or frost, and ecosystems exposed to pollution reorganize to accommodate it. The tendency to consider humans and their stressors as being outside of the ecosystem is common in modern thought. This conception generally holds that human influence, such as pollution, leads to a degraded ecosystem (Figure

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