Moreover, understanding larger-scale phenomena is central to any scientifically rational plan for biodiversity conservation and maintenance.

The Spatial Continuum

''... the problem is not to choose the correct scale of description, but rather to recognize that change is taking place on many scales at the same time, and that it is the interaction among phenomena on different scales that must occupy our attention."

S.A. Levin (1992, p. 1947)

Biodiversity depends on processes operating at many different spatial, temporal, and organizational scales (S.A. Levin, 1992). In general, these scales are broadly overlapping, with processes interacting among scales (Fig. 1). The most relevant scales for studying particular species or dynamical interactions among species will not be the same as for others, and hence there is no single correct set of scales for viewing a system. Rather, there must be awareness of the selective filter a particular perspective imposes on observed dynamics and of how information is transferred across scales (Ricklefs, 1987, 1990; Underwood and Petraitis, 1993).

A "patch" is an initially relatively uniform portion of a habitat whose limits

Figure 1

The spatial scales of variability associated with physical and biological processes (adapted from NRC, 1987).

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