Rivers and Soils: Parallels in Carbon and Nutrient Processing

E cologists usually study systems at spatial and temporal scales (e.g., from centimeters to meters and from minutes to days) that are within easy range of human perception. Critical ecological processes, however, occur over a range of spatial and temporal scales-from small and fast to big and slow. Only when the natural scale of organisms overlaps the scales easily perceived by humans are the roles of organisms readily understandable. Thus, ecologists know a great deal about the lives and roles of birds, mammals, and fishes in ecosystem processes but far less about the individual roles of the "little things that run the world" (Wilson 1987)-that is, microbes and microfauna. Most of these organisms operate at rapid paces over very short distances, far smaller than the scale at which ecologists typi-