Responses of northern red oak seedlings to lime and deer exclosure fencing in pennsylvania

In Pennsylvania, two hypotheses compete to explain the chronic oak (Quercus spp.) regeneration problem: excessive deer browsing and soil cation depletion. We tested these hypotheses by evaluating the effect of forest liming and deer exclosure fencing on northern red oak (Quercus rubra L.) seedling growth and nutrition in five oak shelterwood stands in Pennsylvania over 6 years. In each stand, four planting plots were located inside a 2.4 m high woven wire fence and another four were established outside the fence. About 225 northern red oak acorns were planted in each plot in spring 2004. Dolo-mitic limestone was applied to randomly selected plots at rates of 0, 4.5, 9.0, and 13.5 Mg·ha ^-1 during May 2004. There were no statistically significant (P ≤ 0.05) growth responses to lime applications. The only significant growth responses resulted from the fence versus no-fence treatment. A significant (P < 0.003) fence × year interaction for seedling height and root collar diameter indicates differential impacts of deer browsing. By 2009, seedlings inside fences averaged 32 cm tall, while seedlings outside the fences averaged 17 cm. Similarly, root collar diameter averaged 6.6 mm outside the fences and 9.1 mm inside fences.