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
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.
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.
Intensely instrumented White Fir Tree (CZT-1).
Southern Sierra Critical Zone Observatory activities, fall 2009, p 2
Hydrologic modeling
 RHESSys hydrologic
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 in watershed P301
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.
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.
Snow-vegetation interactions
Synoptic snow surveys have
exhibited spatial patterns that
depend on the amount of
precipitation, incident solar
radiation, and canopy
structure.
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.
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.