The River continuum concept (RCC) was an attempt to construct a single framework to describe the function of temperate lotic ecosystems from the headwaters to larger rivers and relate key characteristics to changes in the biotic community (Vannote et al. 1980). The physical basis for RCC is size and location along the gradient from a small stream eventually linked to a large river. Stream order (see characteristics of streams) is used as the physical measure of the position along the RCC.