Impact of Fire on Nutrient Cycles in Mediterranean-Type Ecosystems with Reference to Chaparral

Abstract

Although there is a large literature describing the effects of fire on biogeochemical cycles of nutrients, no studies have quantified the ecosystem effects of fire on intersystem fluxes of nitrogen or other nutrients through a full successional cycle (see reviews of fire-nutrient interactions in Viro 1974; Woodmansee and Wallach 1980; Rundel 1981, 1982). The nitrogen balance of ecosystems with major portions of biomass below ground or with low above-ground coverage (grasslands, tundra, deserts) is not generally effected by fire. Low-intensity ground fires in many forest ecosystems likewise do not have a major impact on nutrient cycles. Chaparral and other mediterranean-type ecosystems, however, have characteristic high-intensity fires at relatively frequent intervals. These fires burn off much of the above-ground biomass and have very large immediate effects on output fluxes of nutrients from the ecosystem and smaller secondary effects on both outputs and inputs of nutrients through successional cycles. There are virtually no quantitative data available for the site and dynamics of ecosystem pools of nutrients during such fires.