IMPACTS OF INVASIVE PLANTS ON MICROBIAL METABOLISM IN COASTAL SAND DUNES OF CENTRAL CALIFORNIA
Ai Tran, Freddy Chou, Christine Case.
Skyline College, San Bruno, CA.
San Francisco’s coastal sand dunes are dynamic ecosystems composed of sand which blows up from the western beaches. Invasive plants, introduced in the 1800s to control erosion and stabilize the dunes, comprise the primary vegetation. Little is known about the effects of these invasives on nutrient cycles. Therefore, we investigated the microbial diversity of different dune habitats: barren dunes, dunes with native vegetation, and dunes with non-native vegetation. Sand was collected from different sites on the dunes. Conditions noted were vegetation, depth at which the sand was taken, and west or east exposure. Community-level physiological profiling employing Biolog Ecoplates was used to compare catabolic activity in the microbial communities. Richness and evenness were calculated using the difference between absorbance of the test substrate wells and the control (water) wells. Samples from west-facing exposures showed higher functional diversity than those of their east-facing counterparts (p < 0.05). Catabolic capabilities of the barren dune and native plant-associated microbial communities are significantly greater than those of the invasive-associated community (p < 0.01). Native Erigeron glaucus sands showed significantly higher functional diversity compared to invasive Carpobrotus edulis-associated sand (p < 0.01). Our results suggest that invasive plants do affect the diversity of soil microbial communities. We will discuss the effects of invasive plants on nutrient cycling as well as developing strategies that return the dunes ecosystem to the pre-invasion state.