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San Dimas Experimental Forest

Established in 1933, the San Dimas Experimental Forest is the only such forest in southern California. It covers 6,945 ha in the front range of the San Gabriel Mountains, located about 50 km northeast of Los Angeles. Originally established as an outdoor hydrologic laboratory to document and quantify the water cycle in semi-arid steeplands, most of the facilities were constructed by the depression-era Civilian Conservation Corps and Work Projects Administration labor programs. San Dimas has a long history as a research site in the fields of hydrology and ecology and is recognized as a Biosphere Reserve by UNESCO's Man and the Biosphere program. San Dimas also contains the Fern Canyon Research Natural Area.

Ecology

Climate

San Dimas experiences a Mediterranean-type climate, with cool wet winters and hot dry summers.

Soils

Soils are characterized by steep topography, semi-arid climate, and crystalline bedrock (Precambrian metamorphics and Mesozoic granitics), which produce shallow, azonal, coarse-textured soils with numerous rock outcrops and low fertility.

Vegetation

San Dimas is covered primarily with mixed chaparral brushfields but also includes areas of coastal sage scrub, oak woodland, and mixed conifers. Some areas were type-converted from native chaparral to grassland during the 1960s.

Facilities Information

Facilities at the Tanbark Flats research administrative site within the San Dimas Experimental Forest include a laboratory/office, residences, a mess hall/ conference room, and several storage/utility buildings. Infrastructure includes water, electricity, propane heating, and phone service. Research/monitoring equipment includes rain gauges, stream gauges, debris dams, water-quality samplers, a weather station, and a historical lysimeter complex.

Lat. 34°12´ N, long. 117°45´ W

Contact

Research, Past and Present

Research has included watershed hydrology, chaparral ecology, water yield, precipitation monitoring, post-fire erosion control treatments, soil non-wetability, hillslope erosion and watershed sediment fluxes, soil nutrient cycling, and bird habitat use.

Major Research Accomplishments and Effects on Management

Major accomplishments and effects of research at San Dimas include the development of rain gauges and raingauge networks to accurately measure precipitation in steep terrain, the development of flumes to measure and withstand debris-laden flows, and the identification of post-fire soil non-wetability.

Research Opportunities

Research opportunities include a broad spectrum of studies in the general fields of watershed hydrology, ecology, biogeochemical cycling, and fire effects.

Long-term Monitoring and Data

Long-Term Databases

Long-term databases include precipitation, streamflow, stream nitrate, temperature, relative humidity, and solar radiation. Also, since 1982 San Dimas has been an air quality monitoring site for the National Atmospheric Deposition Program/National Trends Network.

Collaborators

  • Collaborators include professors of hydrology, soil science, environmental science, ecology, biology, geography, and geology from University of California- Riverside, University of Georgia, University of Iowa, California Polytechnic University-Pomona, Pomona College, and California State University-Long Beach.

Data and Tools

Documents

Publications

Forms

Last updated July 22, 2025
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