Invasion of Grassland by Baccharis pilularis DC

Abstract

A remeasurement of transects established in 1952 and a comparison of early vegetation maps with maps prepared in 1961 indicate that a brush species, Baccharis pilularis, has invaded grassland areas of the East Bay Regional Parks near Oakland, California. The common movement of the species has been as an advancing front on exposed soil occurring at baccharis-grassland boundaries. Experiments with controlled burning and with grazing animals show that baccharis seedlings and young plants are very susceptible to damage from these factors. These experiments support the hypothesis that baccharis has increased due to the reduction of wildfires and the elimination of grazing in the parks. There is need for management to preserve remaining grasslands in the park.