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Pacific Southwest Research Station
800 Buchanan Street
West Annex Building
Albany, CA 94710-0011

(510) 559-6300

San Dimas Experimental Forest

SDEF Home Page | Williams Fire | Fire Severity | Fire Emissions | Water Quality | Water Yield | Ecology | Lysimeters | Resources & Maps | Photos | Management Plan | Site description, Facilities, and Use | The Future of San Dimas

Past Research Summary:

Early research objectives were: 1) to develop methods of vegetation management to obtain maximum water yields with minimum erosion from southern California watersheds; and 2) to determine quantitatively the relation of chaparral vegetation to the hydrologic cycle in mountain watersheds.Throughout the 1930s, 1940s, and 1950s, research focused on hydrologic monitoring of the rainfall-runoff sequence with a network of up to 450 raingages, 17 stream gauges, and several weather stations. Also, water consumption by various plant species was studied in lysimeter and runoff plots. Using these data, attempts to increase water yield through vegetation manipulation were conducted in the Bell and Monroe watersheds.

The lysimeter installation at Tanbark was the largest of its kind in the world, and measured water usage by various plant species. The destructive Johnstone Fire of 1960 halted ongoing lysimeter studies at that time. The soils used in these lysimeter plots, which were homogenized to make them consistent in each treatment, are now being studied for soil horizon development, earthworm activity, heavy metal measurements, and other parameters. Click here to view the lysimeter construction series photos.

Soil research in the SDEF has included some of the pioneering studies on the "hydrophobic" or water-repellent layer which forms following fires. This hydrophobic layer results in increased water runoff in burned areas. The research emphasis changed to post-fire rehabilitation to control runoff and erosion after the Johnstone Fire of 1960. A number of techniques were tested, including: contour trenches, channel checks, and reseeding with various barley and grass species.

In the 1980s and 1990s, research emphasizing ecosystem-level issues such as air pollution, soil genesis, postfire plant and animal succession, vegetation biomass, remote sensing, and nutrient cycling has taken place.


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Last Modified: October 14, 2004