White-tailed Deer Herbivory on Forest Regeneration following Fire and Thinning Treatments in Southern Ohio Mixed Oak Forests

The effects of white-tailed deer browsing on species richness, density and height of forest regeneration were examined on three oak dominated forests in southern Ohio. Each study site consisted of four 20 ha silvicultural treatments, resulting in 12 experimental units. Mean estimated post harvest deer densities were 6 deer km. Three pairs of plots were established within each treatment at each location, and a 2.4 m tall deer exclosure fence was installed around one plot from each pair in the summer 2001. Species and diameter (cm) of all overstory and midstory vegetation were recorded. All woody stems between 10 and 150 cm tall were identified, and height (cm), basal diameter (mm) and evidence of deer browse were recorded in 2001, 2002 and 2003 on sub-plots within each plot. Overall mean height of regeneration was 16.1 percent lower on un-fenced plots, but species richness and seedling density did not differ between fencing treatments. Blackgum, which had 40 percent lower mean heights on unfenced treatments, was the only species tested that was significantly affected by fencing treatment. Silvicultural treatment had no significant effect on overall mean seedling height; however, treatment effects were significant for chestnut oak, red maple and greenbrier. Oak (Quercus spp. L) dominated forests occupy approximately 46 percent of the forestland in the eastern United States (Mc Williams et al. 2002). In Ohio, oak dominates 59 percent of the forestland, and this percentage is even greater in the southeastern portion of the state (77 percent; Griffith et al. 1993). Most of the mature second-growth forest in southern Ohio established following severe disturbance from past agricultural or industrial usage (Hutchinson et al. 2003). Iron furnaces, fueled by charcoal that was produced from repeated cutting of forests, have had a lasting effect of the forest cover of southeastern Ohio (Stout 1933; Hutchinson et al. 2003). Also, during establishment these forests were exposed to repeated fire, with fire return intervals ranging from 5 to 15 years (Sutherland et al. 2003). These frequent fires continued in southern Ohio until organized fire suppression was established in 1923 (Sutherland 1997). At the time these forests became established (mid 1800’s to early 1900’s) white-tailed deer (Odocoileus virginianus Zimm.) populations in southern Ohio were likely to have been in decline (Iverson and Iverson 1999). In fact, from 1904 to 1923 white-tailed deer were absent from Ohio (ODNR 2003). Today, advanced regeneration in these oak dominated forests ranges from high percentages of red maple (Acer rubrum L.) and other shade tolerant species on sites with minimal canopy disturbance to regeneration dominated by pioneer species like yellow-poplar (Liriodendron tulipifera L.) on sites with considerable canopy disturbance (Lorimer 1993). In fact, numerous studies have reported a distinct lack of oak regeneration throughout the oak-hickory region on all but the driest of sites (Clark 1993). Many studies including McCarthy et al. (1987), and Goebel and Hix (1997) have found that advanced oak regeneration is probably inadequate to successfully maintain a significant proportion of oak in these forests following canopy disturbance. Reasons most commonly cited for this lack of oak regeneration include: 1) cutting practices which remove individual trees and often do not supply adequate canopy disturbance to provide sufficient light (Burns and Honkala 1990), and 2) the lack of repeated disturbance from fire since oaks are typically less susceptible to injury and are able to repeatedly produce sprouts (Huddle and Pallardy 1999, Dey 2002, Brose and VanLear 1998). †Natural Resources Specialist (DKA), South Centers, Ohio State University Extension, 1864 Shyville Road , Piketon Ohio 45661; and Professor of Forest Ecology (BCM), Department of Plant Biology, Ohio University, 317 Porter Hall, Athens, OH 45701-2979. DKA is corresponding author: to contact, call (740) 289-2071 or e-mail at [email protected]