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Biology
Completed Project

Tree Seedling Success in Gap Versus Non-Gap Areas: The Interaction Between Light Availability and Deer Browsing

Gabe O’Connor, Vassar College ’16, Sean Hoy-Skubik, Vassar College ’16, Elise Heffernan, Vassar College ’12  and Prof. Lynn Christenson

Browsing activity by white tailed deer (Odocoileus virginianus) can shape the composition and growth of forests, particularly in areas of rapid regeneration, such as in canopy gaps. These areas of increased light transmittance create a favorable environment not only for seedlings and saplings, but also native and invasive vines. These vines can overtop trees and encourage further gap formation. However, a high vine density in a light gap may also protect some tree seedlings from browsing pressure by making it difficult for the deer to reach the seedlings. In our study, we identified and assessed trees, saplings, seedlings, shrubs and vines in three canopy gaps paired with three non-gap areas at the Vassar Farm and Ecological Preserve. We assessed deer browse rates, canopy light transmittance, and soil properties to explore the differences between regeneration in canopy gaps and under intact canopy. Our data indicate that increased light transmittance in gap areas is correlated to higher vine density and increased browsing.  We also found that gaps had fewer total tree seedlings but a greater average height for the existing seedlings.  These data suggest a complex relationship between forest trees, deer browsing and vine competition; all of which will interact to structure our forests.