California annual grasslands are often managed with seasonal grazing and prescribed burning on the assumption that such practices have long-term benefits for native species. Mature native perennial bunchgrasses, particularly purple needlegrass (Nassella pulchra), are often the focal species, but very little is known about responses at different life history stages. This study reports the long-term survival and growth, response of mature plants, and the natural recruitment of N. pulchra into the community. In plots receiving grazing and burning events over the 7-year study period, mortality of mature plants was threefold higher on mounds than on intermounds and likely reflected increased competition intensity associated with increased resource availability in deeper soil. Burning and grazing treatments had strong positive effects on basal area of mature purple needlegrass, but plants in grazed plot that were not burned contained considerable standing dead biomass. Topographic location strongly influenced growth as intermound plants grew relatively more than mound plants, but the effects on growth and burning did not vary with topographic location. The techniques used in this study yielded mixed effects and might not have provided sufficiently long periods of reduced competition from annuals because of the rapidity of reinvasion after treatment and the diversity of weed species present, some of which were not greatly affected by the treatments. Given the documented effects of intense competition from annuals on N. pulchra, it is critical that close attention be given to all life history stages.
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