The watershed approach has long been central in long-term ecological research, allowing for evaluation of whole ecosystem hydrology and biogeochemistry and for evaluation of response to both subtle long-term change (e.g., changes in atmospheric chemistry) as well more dramatic treatments (e.g., clearcutting, land use change). One of the challenges in watershed studies has been defining the importance of biogeochemical transformations in streams as moderators of whole watershed dynamics. The watershed approach has been used in both the Baltimore and Phoenix urban Long Term Ecological Research (LTER) projects to provide comparison with other sites in the LTER network and to facilitate integration between the biophysical and social science domains of Urban Ecology. Interestingly, watershed studies in urban areas have highlighted the importance of streams as they often suffer extreme degradation and are the target of restoration activities. In this talk we review watershed and stream studies in the Baltimore and Phoenix projects with a focus on how they have helped to define the socio-ecological importance of streams.
Urban streams are often characterized by a suite of physical, chemical and biological degradation effects collectively referred to as the Urban Stream Syndrome. At first, recognition of this syndrome reinforced the idea that streams are mere transporters of water and nutrients, with minimal effects on whole watershed dynamics. However, detailed research in Baltimore and Phoenix have shown surprising amounts of biological activity in urban streams, even in buried and highly degraded reaches raising fundamental questions about terrestrial:aquatic interactions and the structure, function and resilience of stream ecosystems. Restoration of degraded streams further enhances their biogeochemical function and has facilitated socio-ecological integration through analysis of the effects of these restorations on human perceptions, values and behaviors. Rather than simple pipes, urban streams are fundamental components of the bio-geo-socio-chemistry of urban watersheds.