The environmental relationships of Californian coastal sage scrub and some of its component communities and species

Abstract

Although the records of the earliest Spanish explorers in California largely avoid explicit mention of coastal sage scrub, they leave little doubt that the formation was present in areas where it exists today. The phenology and morphology of coastal sage scrub is such that it is better adapted than chaparral to occupy the drier parts of the Mediterranean climatic zone. Coastal sage scrub appears more successful than chaparral on argillaceous soils where sage usually occurs in mixture with Quercus agrifolia forest. Fire, while killing most coastal sage shrubs is followed by a rapid recovery of the formation through the agency of the widely dispersed subligneou shrubs, and other disturbances are often followed by a similar invasion. Most of the coastal sage associations and species show some strong correlation with one or several of altitude, a partial surrogate of continentality, aspect, slope or substratum. The major differentiation within coastal sage in the study area relates to continentality. However, the present patterns of distribution of coastal sage scrub and its component associations and species does not always correspond with neat environmental isolines, suggesting that past disturbance patterns have been perpetuated by homeostatic mechanism.