Effects of Ehrharta erecta on the redwood understory and implications for restoration
Physical and Biological Sciences
Plant Sciences
Biological invasions, particularly by exotic grasses, have the potential to reduce biodiversity and to alter ecosystem functions and disturbance regimes in native communities. Ehrharta erecta Lam. (panic veldt grass) is an evergreen perennial grass with life history traits that makes it an aggressive competitor against native species. It spread extensively beyond the sites of its experimental introduction around the central coast region of Northern California in the 1930s, and it has invaded the redwood understory on the UCSC campus. In my study, I compared photosynthetic rates of native species with and without the surrounding invader removed in order to gain insight into the physiological effect of E. erecta on native species. In a separate experiment, I compared the effectiveness of herbicide application and manual removal in controlling E. erecta on the UCSC campus. I evaluated how each treatment influences the recovery of natural communities by planting native redwood understory herb Clinopodium douglasii (Benthe.) Kuntze into treated plots, alongside unplanted controls, in order to examine 1) the effect of E. erecta removal treatments on native survival and growth rate 2) the effectiveness of native vegetation restoration in reducing reinvasion of E. erecta. A better understanding of the degree and mechanisms of impact of E. erecta on native species will serve to guide restoration priorities for invasive species management.
