Biophysical interactions and the structure and dynamics of riverine ecosystems: the importance of biotic feedbacks

Characteristics of streams and rivers reflect variations in local geomorpho logy, climate, natural disturbance regimes and the dynamic features of the riparian forest. Hierarchical interactions between these components result in a rich variety of distinct stream communities which, when considered in combination with strong biotic feedbacks to the physical environment, prese nt formidable challenges in discovering and understanding fundamental, syst em-level characteristics of natural rivers. The objectives of this article are to briefly review the traditional view of hierarchical physical control s on stream structure and dynamics and to show how this viewpoint is changi ng as recognition of strong biological influences on physical structure are emerging. In combination, identifying natural stream characteristics and t he interactions among individual components, as well as recognizing the imp ortance of biotic feedbacks on physical structure, form the basis for estab lishing effective conservation strategies.