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Restoring Erodium macrophyllum (Gerianaceae) to a Southern California grassland: Impacts of fire and invasive species.
Gillespie, Ian*,1, Allen, Edith1, 1 University of California, Riverside, CA
ABSTRACT- As more plant species become endangered and populations extirpated, re-introduction and trans-location will become an increasingly common means for insuring rare species' existence. Local site factors (e.g., fire regime and invasive species) may ultimately dictate the success of rare species restoration. We introduced Erodium macrophyllum, a rare native annual forb, by seeding plots in five different areas in a southern California grassland. For two seasons we monitored their demography in plots manually weeded so that they were free from exotics, (primarily Avena spp., Bromus madritensis and Erodium botrys) and in areas that were burned the spring after seeding. For both seasons, weeding increased seedling establishment, survival and fecundity. When vegetation was burned in June 2001 to kill exotic grass seeds before they dispersed, all E. macrophyllum plants had finished their life cycle, suggesting that burns done at this time would not directly impact their fecundity. However, the following season the burned plots had less establishment of E. macrophyllum, but more establishment of native grass, suggesting burning may differentially affect seedling recruitment. Prescribed spring burning is needed to reduce the exotic seedbank, but studies on impacts and long-term recovery of native plants are still needed.
KEY WORDS: Nassella pulchra, demography, prescribed buring, competition