PARENT SESSION
Monday, August 7, 5:00-6:30 pm
Poster Session 2 - Invasive species
Exhibit Hall, Ballroom Level, Cook Convention Center

Microstegium vimineum (Japanese stiltgrass) abundance and native diversity.

Adams, Sheherezade^*,1, Tessel, Samantha^{1, 2}, Engelhardt, Katharina^{1, 2}, ¹ University of Maryland Center for Environmental Science, Frostburg, MD, USA² Frostburg State University, Frostburg, MD, USA

ABSTRACT- Biodiversity loss is a growing concern for ecosystems throughout the world. Invasive species are often cited as a cause of decline in local native diversity. Previous work on this topic has been inconclusive, with some evidence suggesting that invasive species result in a decrease in biodiversity, and other studies showing invasive species increasing the total species pool without perceptibly affecting the native community. We tested the relationship between the percent cover of an invasive grass, Microstegium vimineum (Japanese stiltgrass), and native richness in 10m square plots at Monocacy National Battlefield in Maryland, USA. The relationship was found to be hump-shaped, with a positive correlation when M. vimineum covered less than 10% of the plot, and a negative correlation when M. vimineum covered more than 10% of the plot. The data suggests that there is a threshold abundance for an invasive species, below which the presence of the invasive does not impact native species diversity. Invasive presence and native diversity are positively correlated at these densities as all species are responding in similar ways to heterogeneous environmental resources. Above this threshold abundance, the driving variable is different, the invasive is competing directly with native species for resources, resulting in a negative correlation. The data suggest that managers charged with protection of biodiversity in natural areas should aim to limit invasions to below this threshold to minimize the impact on native diversity. This is often a more feasible goal than total eradication.

Key words: invasion biology, diversity, herbaceous plants