Abstract/Description or Keywords |
Headwater systems, the areas from which water originates within a channel network, are characterized by interactions among hydrologic, geomorphic, and biological processes that vary from hillslopes to stream channels and from terrestrial to aquatic environments (Hack and Goodlett 1960). Although hydrologic, geomorphic, and biological processes in headwater systems have been studied for the last 50 years and much knowledge related to these systems is available (Hack and Goodlett 1960, Hewlett and Hibbert 1967, Likens et al. 1977), the roles of headwater streams within the watershed and the linkages from headwater to downstream systems are poorly understood. Headwater systems are critical areas for nutrient dynamics and habitat for macroinvertebrates, fish, and amphibians within watersheds (Meyer and Wallace 2001). Because of their geographical isolation, headwater systems also support genetically isolated species; thus, they support an important component of biodiversity in watersheds. For instance, new and endangered species are often found in headwater streams because such streams are relatively unexplored (Dieterich and Anderson 2000). Therefore, understanding the spatial and temporal variations of hydrologic, geomorphic, and biological processes in headwater systems is the key to comprehending the diversity and heterogeneity of riparian and riverine ecosystems. |