The dynamics of the vegetation of riparian areas should depend on the life and death of individuals and on regeneration. To the extent that regeneration represents an opportunity for new species to appear on a site, the dynamics can be considered as a cascade of genetic information across the landscape. This topic has received considerable attention in the general ecological literature under the topic of species dispersal (e.g. Sauer 1988), and I use the word cascade here only to draw a parallel with the relation between spatial pattern and process which has been emphasized in my discussions of cascades of matter and energy. One can consider a flow of species across the landscape, and in order to differentiate this flow from that of matter and energy, information is a general category which summarizes the distinctive aspect of life. Landscape ecology is fundamentally concerned with the movement of species (as well as energy and matter) across space at a variety of temporal and spatial scales (Forman and Godron 1986), but in this discussion I will primarily address the affect of riparian elements on the long-term, coarse-scale movement of species.

Species movement across space

The effectiveness of riparian zones as pathways for, or barriers to, the diffusion of genetic information is not known. Forman and Godron (1986) cited the role, but did not provide examples.