Climate
Mediterranean climate characterized by hot, dry summers and mild, rainy winters. Annual precipation ranged from 9 to 52 inches with a mean of 28 inches, occurring almost exclusively as rainfall, and mostly from October through May. Mean monthly minimum air temperatures are typically in the high 30's and low 40's F. During November through March, while mean maximum air temperatures are around 90 F. during July and August. Recorded extremes are 14 and 109 F.
Climatic Data from 1962 to present
The weather station is operated by USDA and is part of the California Irrigation Management Information System (CIMIS).
Parameters measured:
- air temperature
- relative humidity
- precipitation
- total solar radiation
- net solar radiation
- soil temperature
- wind speed and direction
- evaporation pan
Current forecasts for the Browns Valley Area
Five soil series dominate. Four, usually intermingled, are developed from basic metavolcanic rocks: Auburn, the most extensive, is loam in texture, 1-2 feet deep, well drained and slightly acid; Sobrante, similar to Auburn but 1.5-3 feet deep with slightly more clay in the subsoil; Las Posas and Argonaut, 1.5-3.5 feet deep with clayey subsoils. The fifth series is Wyman, 4-5 feet deep, loam with clay-loam subsoil, formed in alluvium from the four series previously described.
Plants
Unmodified foothill woodland-grassland -- The major trees are blue oak and interior live oak, ranging from 40 to 200+ trees per acre. There are some foothill pine and, at higher evevations, black oak and ponderosa pine. Common shrubs include buckbrush, toyon and poison oak. 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. Perennial grasses include purple stipa. Cleared areas -- Most trees and shrubs have been removed; most resident grasses and forbs remain. Trees have been reduced to 4 to 50 per acre. In one area they have been removed completely. Some areas have been seeded to improved species, including subterranean clover, rose clover, Hardinggrass and ryegrass.
Animals
Oak woodlands in California provide one of the richest habitats in the state for wildlife. It is estimated that approximately half of California's 660 terrestrial vertebrate species utilize oak woodlands at some time during the year. Some of the common mammals at the Center are squirrels, deer, racoons, skunks, foxes, bobcats, coyotes and occasionally, mountain lions. Reptiles include fence lizards, skinks, whiptails, alligator lizards, garter snakes, rattlesnakes, gopher snakes and kingsnakes. Several years ago, a research project conducted a thorough inventory of bird species found at the Center, which is listed below.
Documents are offered in a PDF file format which can be downloaded and opened in Adobe Acrobat Reader.
Forage Production
Range forage production has been monitored monthly during the growing season at a site located at 1450 ft. elevation since 1979.