Stream channels as corridors

As discussed previously, stream channel corridors are critically important features of the landscape. Riparian areas are used by more animal species than any other habitat type. These narrow ribbons of green provide water, food, habitat, and a safe haven for breeding and migrating for a great proportion of terrestrial birds, mammals, reptiles, and amphibians. Riparian areas are also home to many species of aquatic life, including fish, insects, and invertebrates.

An alder-willow riparian community in Oak Creek Canyon, Arizona.

The continued functioning of riparian areas as habitat, filters, corridors, conduits, and sources of food and water is dependent upon the condition of the landscape in the rest of the watershed. The distribution of plant communities in a watershed influences the movement of sediment, water, nutrients, and wildlife. Degraded vegetation cover in an upland portion of the watershed can directly affect stream channel characteristics by resulting in greater runoff and introduction of pollutants into the stream channel. Similarly, increased urbanization can lead to degraded water quality. Though stream channels occupy only a tiny portion of the landscape, the value these areas contribute to ecosystem functioning cannot be underestimated.