HPWREN collaborates with the San Diego State University's Field Station Programs to connect their Sky Oaks Field Station

The Sky Oaks Field Station has been the main SDSU site for chaparral ecosystem research since 1982. Since 1994, intensive studies on the patterns and controls on net ecosystem carbon flux have emphasized the use of eddy covariance tower data. Eddy covariance measurements were conducted in a "young" stand (burned in 1992 by controlled fire) and an "old" stand, last burned in 1901. These two stands of differing ages have formed the basis of the chaparral studies at the Sky Oaks Field Station during the last decade.

Young Stand: Burned in 1992 by a controlled fire, the Young Stand site was established to study the recovery of chaparral after a fire. After six years of continuous measurements, this site burned in a natural wild fire in July of 2003.

Chaparral is a fire-maintained community and typically burns approximately once every 35 years. The recurrence of fire within this vegetation type is a result of the frequently water-stressed conditions and dry, hot Santa Ana winds. The research and educational projects at Sky Oaks were disrupted by a wildfire that swept through the field station on July 16, 2003. After consuming 24,000 acres, the fire resulted in the loss of the two eddy covariance towers. With the help of insurance and new funding, towers were re-established in the now burned old, 102-year-old stand and young (developing), 11-year-old stand. A third tower was also set up in an old, unburned stand that closely resembles the old site before the fire, thereby continuing the long-term flux record at Sky Oaks.

Old Stand: Before burning in the wild fire of July 2003, this stand of chaparral was more than 100 years old. With a base line of more than six years of data before the fire, this site is an excellent chance to study re-establishment of chaparral after a natural fire.

Carbon fluxes, micrometeorological data, and web camera images have been posted for research and educational use in near real-time on-line on the SDSU Web site. Data have also been reported to the AmeriFlux data site at the Carbon Dioxide Information Analysis Center (CDIAC), and have been used in numerous comparative studies. In addition to providing insight on the inter- and intra-annual controls on carbon flux in two chaparral stands of contrasting ages, these data have provided validation of MODIS remote sensing products. The near real-time data from the towers have also been used in K-6 education in San Diego, CA, Barrow, AK, and La Paz, BCS, Mexico (through the NSF-funded GK-12 PISCES Project), as well as in university-level classrooms.

New Stand: The New Stand tower was established in fall of 2003 in an old stand of chaparral that was not burned in the wild fire of the previous July.

The addition of HPWREN to the field station will allow continued and improved dispersal of these unique data sets.

View towards the Mesa Grande HPWREN relay site, approximately 15 miles away.

By Joe Verfaillie, San Diego State University