The Southern Sierra Critical Zone Observatory (SSCZO) is investigating how mountain soil and regolith properties develop over geologic time, and interact with shorter-term climate variability and ecosystem behavior. This understanding is used to predict how environmental change, including human disturbances, fire, pests and changes in climate influence water resources, material flows and forest health. We are pioneering low-cost, accurate measurement systems and use of the measurements to drive advanced earth systems modeling for predictions. We work closely with regional stakeholders and use our results to assess options available to resource managers to enhance management of forests, water and other ecosystem services, given environmental change.
The SSCZO is also a community platform for research on critical-zone (CZ) processes, both locally and as part of the broader CZO national network. It lies along a steep elevation transect where precipitation grades from dominantly rain to dominantly snow and ecosystems range from oak savannah biomes to subalpine forests. Spatial gradients in CZ properties and processes permit substitution of space for time, making the SSCZO an excellent natural laboratory for studying how the CZ responds to disturbance and how the water cycle drives CZ processes. SSCZO research involves a core SSCZO team from 6 campuses, plus collaborators and cooperators from other institutions who use SSCZO data and other resources in their research. SSCZO resources include 4 focal sites spanning a 3000-meter elevation range with gradients in climate, regolith properties, soils, vegetation and material cycles. Measurements are intensive and detailed, including 4 flux towers, meteorological stations, soil lysimeters, groundwater wells, and over 1000 continuous sensors for snow depth, soil moisture, streamflow, water quality and sap flow.
The SSCZO provides a platform for research in a landscape with vital importance to society, yet poorly understood in its potential response to climate warming. The twin threats of a changing climate and land-use practices raise fundamental questions about the sustainability of CZ services in the semi-arid U.S. West, which depends heavily on seasonally snow-covered mountains for many of these services. The Sierra Nevada provides ecosystem services, ranging from water to biodiversity, to a large fraction of California's and thus the nation's population. SSCZO partnerships with federal, state, and local resource-management agencies show the interest that decision makers have in using both research results and SSCZO technology to improve predictive capabilities. SSCZO will provide data and lessons to enhance the science experience of thousands of middle- and high-school students, several undergraduate students and the public.
