Population and Community Dynamics

Abstract

The study of urban ecology must address the scientific debate on how biodiversity relates to ecosystem function, stability, and resilience (Peterson et al. 1998). Though the term biodiversity has multiple definitions and interpretations, the definition provided by Wilson (1992, 393) may best capture its essence. Wilson emphasizes the variety of organisms considered at all levels, from genetic variants belonging to the same species through arrays of species to arrays of genera, families and still higher taxonomic level, as well as the variety of ecosystems, which comprise both the communities of organisms within particular habitats and the physical conditions under which they live. Ecological scholars disagree on the role that biodiversity plays in the functioning of ecosystems: The issue is not simply what species are involved in what specific ecosystem functions, but the importance of diversity for the functioning of ecosystems and the role that it plays in their resilience (Loreau et al. 2001). Scientists also disagree on what drives the patterns of species diversity and the nature of ecological communities. Different theories can be distinguished based on whether they see community assembly as based on niches (MacArthur 1970, Levin 1970), or dispersal (MacArthur and Wilson 1963), and whether they are neutral (treating individual species as essentially identical) (Hubbell 2001) or non-neutral (assuming that different species behave in different ways from one another) (Ehrlich and Ehrlich 1981, Walker 1992, Levin 1999). The lack of resolution on these different perspectives may simply indicate that they are all true at some level (Hubbell 2001). At the same time, they all share a biased disciplinary perspective: They fail to appreciate the mutual interactions and feedback between ecosystem function and biodiversity. These different perspectives have important implications for conservation, and for efforts to integrate humans into ecological thinking.