Joint Influence of Deer Management and an Invasive Grass on Tree Seedling Establishment at Catoctin Mountain Park
John Paul Schmit- Quantitative Ecologist, NPS, National Capital Region Inventory and Monitoring Program
Mid-Atlantic forests face high deer density and invasion by exotic species. Deer browse kills seedlings, preventing the establishment of new trees. Invasive plants can harm seedlings through shading, competition or allelopathy. Catoctin Mountain Park has had reduced tree recruitment due to high deer density for many years. In 2009, the park began culling deer. However, since then the exotic grass Microstegium vimineum has spread through much of the park. Using data from a forest monitoring program we assessed the effects of deer management and Microstegium on tree seedlings. Deer management has resulted in a significant increase in the number of seedlings, from ~629 ha prior to deer management to ~6020/ha most recently. Cover of Microstegium increased from 11.8% of the park to 17.2%. Surprisingly, plots with high Microstegium cover also had increased seedling density, indicating that the spread of Microstegium is not undermining the goals of deer management.