Fire and grazing in a shrub-invaded arid grassland community: independent or interactive ecological effects?

This study examined the response of summer and winter annuals and perennials in a shrub-invaded arid plant community to combinations of fire and grazing by cattle to determine their effects on individual abundances, species richness and diversity. Thirteen species differed significantly in abundance across the burn treatment while nine differed significantly across the grazing treatment. Summer and winter annual plants were significantly more abundant, and summer annual plant species richness and diversity were significantly higher on burn plots. Most species were affected either by burning or grazing indicating that these disturbances affect this plant community relatively independently. (C) 1999 Academic Press.