Site Characteristics

The investigation was conducted in the northern Sierra Nevada foothills at the University of California Sierra Foothill Research and Extension Center, approximately 30 km east of Marysville, CA (39^o15'N, 121^o17'W). Here is a view of the study site.

The climate is Mediterranean, with cool moist winters and hot dry summers; mean annual precipitation is 730 mm and mean annual temperature is 15^o C. Soil water potentials remain below -1.5 MPa at the 0-30 cm depth for approximately five months each year.

The dominant tree species was blue oak (Quercus douglasii H.&A.), a winter-deciduous oak, with associated interior live oak (Quercus wislizenii A. DC.), an evergreen oak. The oak stocking ranges from 90-200 trees per hectare with an average canopy coverage for the watershed of approximately 70%.

Major forbs include filaree, annual clovers and geranium. Common annual grass species are soft chess, ripgut brome, red brome, annual fescue, wild oats, and medusahead. The oak understory community has lower species richness and a somewhat different group of plant taxa than the open grasslands.

Soils within the study area formed in basic metavolcanic (greenstone) bedrock and are classified as fine, mixed, thermic Typic Haploxeralfs.