Animals and Ecosystem Functioning in Streams and Riparian Areas

Animals make important contributions to shaping the ecosystems where they live, by consuming resources, excreting nutrients, and serving as food for other animals. Classically, many people think of organisms as acting in response to environmental conditions. But organisms actually create some of those conditions through their activity, forming a dynamic feedback between living and nonliving parts of ecosystems.

Here, I’ll discuss work that my research group has conducted in stream and riparian ecosystems. In streams, aquatic macroinvertebrates process terrestrial leaf litter, and incorporate it into aquatic food webs. We have found that the rate of this ecosystem process varies nonlinearly with macroinvertebrate population densities, which is an important consideration when predicting hotspots and cold spots of resource cycling. Around streams, terrestrial wildlife use riparian habitats for food, water, shelter, and as movement corridors. I’ll present new results about what determines how wildlife use these areas, and what this implies for ecosystem processes in these ecotone habitats.