Habitat Differentiation among Herbs in Postburn Californian Chaparral and Coastal Sage Scrub

O'Leary, John

Habitat differentiation of herbs ("pyrophyte endemics") appearing during the first postburn spring in southern Californian chaparral and coastal sage scrub was examined. Study sites were classified by aspect (N or S), substrate (andesite and sandstone), and elevation (150-m intervals). Soil analyses revealed several significant differences in physical and chemical properties between the two soil types, but none between N and S slopes. During the peak of the spring growing season, herbs and vines collectively accounted for 32% of the ground cover and 84% of the total plant cover. A few dominant species contributed the bulk of the cover. Most of the dominant species showed aspect preferences and some had pronounced substrate affinities as well. Factors such as temperature and available moisture associated with insolation differences on opposing slopes likely exert primary controls upon aspect preferences. Soil temperature differences on opposing slopes during wildfires may influence seed survival and also act as a selective factor influencing species distributions. Within aspect groups multiple regression analyses most frequently identified total nitrogen and elevation as edaphic variables best related to foliar cover for the various species.

Habitat Differentiation among Herbs in Postburn Californian Chaparral and Coastal Sage Scrub

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