Vulnerability of Oak-Dominated Forests in West Virginia to Invasive Exotic Plants: Temporal and Spatial Patterns of Nine Exotic Species Using Herbarium Records and Land Classification Data

Are oak-dominated forests immune to invasive exotic plants? Herbarium and land classification data were used to evaluate the extent of spread of nine invasive exotic plants and to relate their distributions to remotely-sensed land use types in West Virginia. Collector-defined habitats indicated that the most common habitat was roadsides, but seven of the nine species were found in forests. Regression analyses indicated that the most significant variables were urban land use and population per km², but these were only significant for three of the species. Detrended correspondence analysis showed a forest to urban gradient and that one of the species, Rosa multiflora, was significantly correlated to heavily forested counties while Ailanthus altissima was significantly correlated with more urbanized counties. Although forests clearly are not immune to invasion, the lack of spatial and temporal patterns among the species support the need for intensive plot-level monitoring before predictions of spread can be made.