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Abstract
Effects of canopy opening and white-tailed deer on ground level vegetation are being assessed in south-central Pennsylvania. Herbaceous plants and woody seedlings are being monitored in three unevenaged, mixed oak woodlots at Gettysburg National Military Park. Canopy opening levels on 0.20 ha treatment units were closed (~100% canopy), small (50-60% canopy) and large (0% canopy). Number of white-tailed deer during April have averaged about 0.40 deer per ha since 1992. Overstory treatments were conducted in March 1993. Fences to exclude deer were installed on one-half of the understory inventory plots. Before treatment inventories (1992) of the July herbaceous vegetation indicated 30% of the ground was covered by broadleafs, grasses and vines. Total herbaceous coverage increased to 54% of the area in the first growing season after treatment. Woodlot, canopy opening and fencing significantly influenced the coverage of herbaceous vegetation. Overall, total herbaceous coverage increased from 38% in the closed canopy treatment to 50% and 75% in the small and large canopy treatments, respectively. Compared to before treatment values, overall total herbaceous coverage in the first growing season after treatment increased 19% on all unfenced plots and 30% on all fenced plots. Before treatment inventories of the woody vegetation recorded an average of 5.6 shrub and 4.0 tree species seedlings per m². In the first growing season after treatment, number of shrub and tree seedlings increased to 6.7 and 8.6 stems per m², respectively. Ash dominated the tree species with an average of 2.0 seedlings per m² before treatment and 2.5 seedlings per m² after treatment. Average number of oak seedling in the first growing season after treatment (0.9 per m²) was the same as before treatment. Woodlot was the only factor that consistently influenced the number of before and after treatment seedlings. Before treatment average numbers of shrub and tree seedlings were 12.3, 6.9 and 9.5 per m² for Bushman Hill, Herr Ridge and Powers Hill woodlots, respectively. In the first growing season after treatment, average number of shrub and tree seedlings for Bushman Hill, Herr Ridge and Powers Hill increased to 15.2, 7.8 and 13.1 per m², respectively. Overall, there were 2.1 shrub species and 3.7 tree species germinates in the first growing season after treatment. Most abundant germinates were ash (0.6/m²), grape (1.7/m²), redbud (0.2/m²) and yellow-poplar (2.9/m²), Canopy treatment and litter conditions, but not fencing, significantly influenced the abundance and species composition of the germinates.
Parent Publication
Citation
Bowersox, Todd W.; Storm, Gerald L.; Tzilkowski, Walter M. 1995. Canopy openings and white-tailed deer influence the understory vegetation in mixed oak woodlots. In: Gottschalk, Kurt W.; Fosbroke, Sandra L. C., ed. Proceedings, 10th Central Hardwood Forest Conference; 1995 March 5-8; Morgantown, WV.: Gen. Tech. Rep. NE-197. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 206-213
