Toward Gleasonian Landscape Ecology: From Communities to Species, From Patches to Pixels

The fusion of individualistic community ecology with the Hutchinsonian niche concept enabled a broad integration of ecological theory, spanning all the way from the niche characteristics of individual species, to the composition, structure, and dynamics of ecological communities. Landscape ecology has been variously described as the study of the structure, function, and management of large heterogeneous land areas. Any reading of the published landscape ecology literature shows near uniformity in the adoption of a categorical patch-mosaic paradigm. However, if biological communities are multivariate gradients of species composition, with each species responding individualistically to particular combinations of limiting factors, is a categorical patch-based representation appropriate? We evaluate the sufficiency of several patch-based representations of vegetation at the landscape level to explain the composition of the plant community. Classified vegetation maps all performed poorly in explaining the composition and structure of forest trees among plots. Different categorical vegetation maps provided largely independent explanations of species variability. Individual species models based on spectral, topographic, and climatic variables vastly out-performed those produced using the classified maps. By moving from a landscape ecological paradigm based on categorical patches to one based on quantitative species and environmental responses across continuous space, it will be possible to both produce much more effective predictions of species distributions and ecological processes and remove much of the disjunction between landscape ecology and mainstream community ecology theory.