Chaparral Succession in a San Gabriel Mountain Area of California

Succession in chaprral stands dating to wildfires of 1896 and 1919 was studied on the San Dimas Experimental Forest. Data from 20 pairs of one—hundredth acre plots were segregated by the Uppsala method into five plant associations, each having two or more species in common. Ceanothus and chamise were being eliminated from north—facing stands which then were dominated by scrub oak, holly—leaved cherry, and redberry. Given fire protection, a low oak woodland is expected to develop on these north sites. Although ceanothus had all but disappeared from older stands on south—facing slopes, chamise and black sage were increasing in numbers. A few mountain—mahogany, sugar bush, and redberry shrubs were competing successfully on these exposures and in the absence of fire they might prevail. The composition of future south slope stands, however, is expected to change very little. Future north slope stands will be dominated by plants which were infrequent in the long unburned community.