Analytical Approaches for Understanding Ecosystem Response to Environmental Change Papers included in Watershed 96 proceedings reflect the opinions of the authors and do not necessarily represent official positions of the Environmental Protection Agency. Plesae note that images for this session of the Watershed 96 Proceedings are not available at this time, but will be available soon. Introduction Biogeochemical studies in small watersheds provide an analytical approach to understand how ecosystems respond to natural climatic variations and human-induced environmental change. Watersheds comprise discrete hydrochemical environments allowing quantification of hydrologic, element, and energy budgets. Element budgets, or mass balances, can be quantified as the difference between the mass of a solute that enters a watershed in wet and dry deposition and leaves a watershed in streamflow.
Element budgets are primary tools used to investigate biogeochemical processes.
Monitoring various aspects of element budgets to assess ecosystem health and stability is analogous to measuring the pulse or blood chemistry of a patient. Monitoring streamwater chemistry, basic climate, soil, and biotic variables provide a means to integrate complex biogeochemical processes and evaluate trends in water quality. Small watershed studies provide a scientific basis to develop predictive models of watershed function. Major emphases of small watershed studies include investigation of hydrologic and chemical responses to natural climate variation, anthropogenic stressors, and alternate forest-management practices. The U.S. Geological Survey, U.S. Department of Agriculture Forest Service, and other federal agencies support several long-term small watershed studies to provide insight into a variety of ecosystem processes.