Constraints On Applying Ecology

Managers must recognize that there are many questions that science can not answer. For example, science can not dictate which elements of nature merit conservation. Determination of what to conserve depends on human values (Lawton 1997; McPherson 2001b). An exponential human growth rate precludes preservation of all genetic diversity, species, and ecosystems: humans use a disproportionate percentage of Earth's resources, which contributes to the loss of biological diversity at all levels (Vitousek et al. 1986). Ecologists can provide objective information about objects or processes under consideration for conservation, but the ultimate choice about whether or how much to conserve is beyond the realm of ecology. This debate is centered on the extent to which natural resources should be used to support human activities. Once society has made a decision about what to conserve, ecology can provide the tools for evaluating the success of conservation efforts. These tools will have maximum utility when the objectives are clearly stated and when they can be quantified (Chapter 1).

Ecology can serve as a framework for addressing many questions relevant to management, but there are constraints on this process. For example, the speed of scientific inquiry rarely matches the urgency of environmental problems. In addition, the complex nature of most environmental problems precludes simple solutions that can be easily applied to many sites. Finally, scientific findings are subject to revision or reinterpretation: managers become frustrated and may abandon ecology as a source of information when it appears that ecologists change their minds about the relevant facts.

Frustration notwithstanding, resource managers require reliable scientific information to manage ecological communities and processes effectively. The volume of available data on these topics is overwhelming, and individual managers must identify and extract the relevant information in order to address management issues. Additional factors contribute to the difficult dilemma that managers face as they attempt to incorporate scientific knowledge into management decisions: (1) much of the available information is contradictory or inconsistent, and (2) many scientists still attempt to provide mechanistic explanations about ecosystem function based on descriptive research. This latter tendency has trapped scientists into making predictions about things they cannot predict (Peters 1991; Underwood 1995). Adherence to scientific principles, including hypothesis testing, will improve communications between resource managers and scientists while increasing the credibility of both groups.

The terminology of scale

Confusion and misunderstanding between ecologists and managers result at least partially from different perceptions of scale and associated differences in terminology (Allen and Hoekstra 1992). The selection of labels for levels of organization is a human activity: there are no absolute levels of organization, independent of the observer. Further, the selection of a level depends on the phenomena of interest. For example, ecologists and managers could use guilds or trophic levels instead of communities as the basis for study and communication, depending on the specific phenomena under observation. Confusion results from the inherent subjectivity associated with identifying and communicating about levels of organization.

Contrary to typical interpretations, the labels that are commonly used to describe ecological phenomena are not necessarily size ordered. For example, a forest community may contain a single organism (a rotting tree) that encompasses several ecosystems. Similarly, a single organ of a ruminant organism (the rumen) may contain an ecosystem. To "size order" these attributes (sensu Figure 5.4) is to define the scale of interest; this process represents a definition, but it may or may not accurately represent nature. This would not be problematic, except for the considerable difficulty in linking levels of organization (Allen and Hoekstra 1992). Common phenomena must be used to link different levels (e.g., cycling of a specific element, or growth). Terminology of phenomena must also be consistent - e.g., individual competition at the level of individuals at temporal scales of years is not equivalent to competition at the level of populations over evolutionary time. Strict adherence to labels, in the absence of appropriate context, generates difficulty in communication and, therefore, confusion.

The "tower" model of organization (Figure 5.4) provides a familiar example with which to illustrate this problem. This model clearly does


Biome Landscape Ecosystem Community Population Organism

Figure 5.4 Eight levels of organization in ecology arranged in a straight tower.

not represent a size-ordered view of the world. It is intended to provide generality, yet it actually accounts for relatively little flow of energy or materials through ecosystems (Allen and Hoekstra 1990, 1992). We recognize that the use of traditional terminology will continue (e.g., labels associated with the tower model), and we believe that this use is appropriate if it is recognized that most labels are arbitrary, subjective categories that are not scale defined. In fact, use of traditional terminology is preferred over the development of new terms in the absence of new concepts (Mcintosh 1980) (Figure 5.5).

Ecology and management within a socio-political context

There are some indications that ecology is primarily a "social" activity, which is consistent with Beckett's (1990) view about all scientific activities. For example, ecology is characterized by "invisible colleges" of colleagues that influence the development and resulting application of ecological theory (Mcintosh 1980). An extreme interpretation of this view suggests that ecological theory is largely a function of sociology, an arena in which science is severely constrained. Ecologists influence the outcome of scientific investigations by selecting the level of study (e.g., organisms, populations, ecosystems) and the phenomena of interest (e.g., growth, energy flow). Ideally, these decisions are made with an aim toward the generation of reliable knowledge via hypothesis testing (sensu Chapter 1).

Figure 5.5 Forest canopy cover can be estimated with an ocular tube or "moosehorn" (Garrison 1949; Cook et al. 1995). Photo by Stephen DeStefano.

The phenomena that are observed and described depend on the level of organization selected by the observer (Allen et al. 1984). For example, a physiological ecologist who chooses to focus on leaf-level phenomena will probably advance our understanding of population dynamics very slowly or not at all. Similarly, an ecologist who studies trends in populations over space or time will probably fail to uncover mechanistic explanations for changes in populations at lower or higher levels of organization. Because few individuals have the intellectual capacity or energy to understand numerous levels of organization, important ecological knowledge probably lies undiscovered by the relevant investigators. Inability to link ecological subdisciplines hinders the development of ecology as either a predictive or explanatory science. Similarly, natural resource managers do not have sufficient time to read the ecological literature and link together information from various sources. The resulting failure to integrate information across several levels of organization undoubtedly constrains the effective application of ecological information.

Ecologists exert considerable influence on the patterns and processes that are discovered and described because investigators select the domain of interest. Such selection is usually done with little or no input from the management community. For example, ecologists have been captivated with the study of competition for at least a century, and this fascination has come at the expense of studies on other processes. Several hypotheses have been offered to explain the focus on competition (Keddy 1989): (1) scientists are influenced by their culture, and ecology has developed rapidly in the United States; (2) competition is obviously interesting to people, especially in contrast to other ecological processes; (3) gender bias in the male-dominated field of ecology has favored studies of aggression rather than, for example, mutualism; (4) ecological research is highly atypical of organisms occupying the earth, with a taxo-nomic bias in favor of vertebrates; (5) competition within the scientific community has selected for aggressively competitive individuals; and (6) elitism within the ranks of ecology has allowed relatively few individuals to set the agenda for the entire discipline.

Ecologists also select the grain and extent of studies, and these attributes determine the limits on the spatial and temporal scale of observable phenomena. Coarse-grained studies (e.g., studies that rely on satellite imagery) can not detect fine-grained phenomena (e.g., dietary requirements of a specific bird species), and fine-grained studies are ineffective for the determination of large or long-term processes (e.g., suc-cessional pathways).

Obstacles to communication may also interfere with the progress of ecology and its application. The inherent subjectivity of peer review makes the process vulnerable to bias and inconsistency. In some disciplines, the perceived status of authors and consistency of the results with orthodox views may be more important than the quality of the research in determining whether research is published (Mahoney 1976; Peters and Ceci 1982; Keddy 1989). Although the process of peer review has not been studied in ecology, there is no reason to believe that ecolo-gists are less susceptible to bias than other scientists. A partial solution to this problem would be double-blind reviews of research proposals and manuscripts, which are common in some disciplines but rare in ecology and management.

Despite the presence of these constraints on the development of scientific knowledge, we do not hold a postmodernist philosophy about ecology, and we are not suggesting that ecology is characterized by scientific relativism (sensu Dennis 1996). Ecology operates within the sphere of a single physical universe characterized by facts, patterns, and processes that are known or knowable by all observers. Although the pace of discovery is influenced by the socio-political and cultural environment, we do not question the existence of these discoveries or the associated facts. In this way, science is distinct from art: whereas a significant artistic contribution could come only from a specific artist, a scientific contribution will be discovered (if not by a particular scientist, then by another at a later time). However, we believe that some controversies can be resolved by recognizing the relative importance of socio-political or cultural factors in the debate.

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