Monitoring ecosystems in the Sierra Nevada: The conceptual model foundation

Monitoring at large geographic scales requires a framework for understandin g relationships between components and processes of an ecosystem and the hu man activities that affect them. We created a conceptual model that is cent ered on ecosystem processes, considers humans as part of ecosystems, and se rves as a framework for selecting attributes for monitoring ecosystems in t he Sierra Nevada. The model has three levels: 1) an ecosystem model that id entifies five spheres (Atmosphere, Biosphere, Hydrosphere, Lithosphere, Soc iocultural), 2) sphere: models that identify key ecosystem processes (e.g., photosynthesis), and 3) key process models that identify the "essential el ements" that are required for the process to operate (e.g., solar radiation ), the human activities ("affectors") that have negative and positive effec ts on the elements (e.g., air pollution), and the "consequences" of affecto rs acting on essential elements (e.g., change in primary productivity). We discuss use of the model to select attributes that best reflect the operati on and integrity of the ecosystem processes. Model details can be viewed on the web at http://www.r5.fs.fed.us/sncf/spam_report/index.htm (Appendix se ction).