Southern Sierra Critical Zone Observatory Activities from 2009 annual report

1. Southern Sierra Critical Zone Observatory Activities from 2009 annual report Integrated research on hydrology, ecology, biogeochemistry & weathering across the rain-snow transition Investigators: UCM: R. Bales (PI), M. Conklin, S. Hart, A. Behre UCB: J. Kirchner, S. Glaser UCI: M. Goulden UCD: J. Hopmans UCSB: C. Tague UNR: D. Johnson UWy: C. Riebe PSW: C. Hunsaker Collaborators: UCD, UNR, UCM, UCLA, UCR, CU Research support: National Science Foundation Research partner: Pacific Southwest Research Station, U.S. Forest Service • Core measurements • Streamflow, stream chemistry and meteorological measurements by PSW are ongoing in 10 catchments. • Nodes measuring soil moisture and temperature, snow depth, and solar radiation in place around 13 trees at two elevations and 5 aspects. • Nodes in the water-balance transect located around the flux tower instrumented with over 250 sensors, using the DUST wireless network. The network , which is self meshing and self healing, consists of 60 motes relaying data to a central mother station. • Data are being shared with internal and external users through a digital library, with raw data available upon download and processed data within weeks of acquisition Schematic of self-meshing, self-healing DUST wireless network. Node measuring soil moisture and temperature, snow depth, and solar radiation under canopy, at the drip edge and in the open. • Intensive measurement site • A white fir (CZT-1) was instrumented with over 150 sensors including soil moisture, temperature, and matric potential sensors, soil lysimeters, snow depth sensors, and nutrient resin probes arranged in a radial array around the tree. • Snowmelt patterns around CZT-1 are observed in time lapse photography captured in time-lapse video. Intensely instrumented White Fir Tree (CZT-1).

2. Southern Sierra Critical Zone Observatory activities, fall 2009, p 2 • Meadow water balance • The intensive water balance instrumentation of Long Meadow in 2008 has yielded a 24-hour water balance for the meadow. • Stream pool stratification was observed and investigated further, with manuscripts in preparation. • Spatial and temporal distributions of soil moisture, using geophysical and point measurements, in the meadow are being analyzed. • Lessons learned in Long Meadow are being applied to instrumentation and investigation of the shallow meadow in the KREW watershed P301. • Hydrologic modeling • RHESSyshydrologic model was calibrated for 4 sub-watersheds in the Southern Sierra CZO. • Initial simulations for baseline and 2oC temperature increase show expected reductions in snow water equivalent. RHESSys estimates of spatial pattern of peak SWE for baseline and 2 °C warming scenario • Flux tower • The tower in watershed P301 has been up and operating for over one year. • Data show that photosynthesis in the rain-snow transition did not shut down due to water stress or cold temperatures in water year 2008-2009. • Installation of 3 flux towers along an elevation gradient from oak woodland up through red fir is in progress. These locations are expected to become NEON sites in the future. • Biogeochemistry • Sampling for organic carbon in the KREW streams commenced in April 2009. These samples have been collected for the cross-CZO organic carbon study. • Litter-layer water and soil nutrient sampling has continued. Initial results indicate that the SSCZO systems are not nitrogen limited. • Geochemistry & weathering • The first full field season of sampling for physical weathering is nearing conclusion. Sampling has been conducted in several locations in the SSCZO and analysis is under way. • Initial analysis of geochemical samples collected on a bi-weekly scale by the Pacific Southwest Research Station staff has commenced. • Mixing models analysis of major ions is underway. • Major ions, phosphate and dissolved inorganic nitrogen exhibit inter-annual and elevation-gradient trends. Flux tower in watershed P301 • Snow-vegetation interactions • Synoptic snow surveys have exhibited spatial patterns that depend on the amount of precipitation, incident solar radiation, and canopy structure.