Landscape Boundaries : Consequences for Biotic Diversity and Ecological Flows

The emergence of landscape ecology during the 1980s represents an impor- tant maturation of ecological theory. Once enamored with the conceptual beauty of well-balanced, homogeneous ecosystems, ecologists now assert that much of the essence of ecological systems lies in their lumpiness. Patches with differing properties and behaviors lie strewn across the land- scape, products of the complex interactions of climate, disturbance, and biotic processes. It is the collective behavior of this patchwork of eco- systems that drives pattern and process of the landscape. is not an end point This realization of the importance of patch dynamics in itself, however. Rather, it is a passage to a new conceptual framework, the internal workings of which remain obscure. The next tier of questions includes: What are the fundamental pieces that compose a landscape? How are these pieces bounded? To what extent do these boundaries influence communication and interaction among patches of the landscape? Will con- sideration of the interactions among landscape elements help us to under- stand the workings of landscapes? At the core of these questions lies the notion of the ecotone, a term with a lineage that even predates ecosystem. Late in the nineteenth century, F. E. Clements realized that the transition zones between plant communi- ties had properties distinct from either of the adjacent communities. Not until the emergence of patch dynamics theory, however, has central signif- icance of the ecotone concept become apparent.