Plant Invasion and Biodiversity Patterns at a Maryland Preserve

Abstract

The Audubon Society of Central Maryland’s 55-hectare Fred J. Archibald Audubon Sanctuary in Maryland’s Piedmont physiographic region is an important wildlife habitat under threat from residential and commercial development that will soon be encroaching on all sides. The potential fostering of nonnative plant species by this development poses a significant risk to native plant biodiversity at the preserve, with resulting impacts to higher trophic levels, particularly phytophagous insects and insectivorous birds. Plant communities in 12 field and forest stands throughout the preserve were sampled for species presence/absence and percent cover. Various biodiversity measures were calculated for each habitat, including richness, alpha diversity, beta diversity, and nonnative cover. Three nonnative plant species in particular were found to be encroaching on certain plant communities at the preserve: Microstegium vimineum (Japanese stiltgrass), Persicaria longiseta (oriental smartweed), and Celastrus orbiculatus (Oriental bittersweet), of which the latter may present the most substantial concern, especially to the overstory of forested stands. Although nonnative cover was high in certain stands, pockets of native biodiversity persisted, suggesting the continued importance of these areas to native fauna. Combinations of native and nonnative diversity measures present a potential schema for assigning management regimes to stands, with strategies ranging from low to intense levels of management.