Long-term impacts of deer exclosures on mixed-oak forest composition at the Valley Forge National Historical Park, Pennsylvania, USA1

Abstract

Abstract Odocoileus virginianus Zimmerman (white-tailed deer) populations at Valley Forge National Historical Park in southeastern Pennsylvania have ranged from 70 to 93 deer per square km over the last decade. In 2010, we surveyed 30 fenced (to exclude deer) and unfenced paired plots established in 1992 to evaluate differences in woody and herbaceous vegetation. In addition, a broader collection and analysis of overstory and understory vegetation data were conducted in the two dry Quercus spp. forests and one mesic Liriodendron tulipifera L. forest that contain the fenced and unfenced plots. The understory of the Liriodendron stand had 72% cover of Microstegium vimineum, (Trin.) A. Camus, an exotic grass. Across all three stands, sapling and seedling densities were low to moderate (500 and 10,000 stems ha−1, respectively) and were primarily shade tolerant Acer rubrum L. and Nyssa sylvatica Marsh. The numbers of Quercus seedlings and saplings were low to nonexistent in all stands. Similarly, the unfenced ...