Use of turtlehead (Chelone glabra L.) and other herbaceous plants to assess intensity of white-tailed deer browsing on Allegheny Plateau riparian forests, USA

One of the key factors affecting the integrity of forest ecosystems in port ions of the eastern United States is heavy browsing by overabundant populat ions of white-tailed deer (Odocoileus virginianus Zimmerman). Deer impacts to upland forests of the Allegheny Plateau in northwestern PA, USA, have be en especially intense: high levels of deer browsing over the past 60 years have strongly influenced forest pattern and process. Riparian forests of th e region are rich in herbaceous plant species, but virtually nothing is kno wn about how deer browsing may influence the structure and function of thes e systems. Moreover, reliable techniques for assessing and monitoring deer impacts on riparian forests are lacking. The goal of this study was to dete rmine whether the common riparian herbaceous plant turtlehead, Chelone glab ra L., is a useful indicator species with which to assess and monitor the i ntensity of deer browsing in the herbaceous layer of Allegheny Plateau ripa rian forests. The percentage of C. glabra stems browsed by deer was signifi cantly correlated with intensity of browsing on the herbaceous community du ring one sample period, but stem height, an attribute used widely in other studies of browse indicator species, was poorly correlated with intensity o f browsing. Three other herbaceous plant species, Aster divaricatus L., A. prenanthoides Muhl. and Impatiens capensis Meerb., were preferentially brow sed by deer and show promise for use as indicators of browsing intensity in riparian forests. Variability in deer browsing intensity on C. glabra acro ss sites and sample periods suggests that use of an assemblage of herbaceou s browse indicator species is preferable to sole reliance on C. glabra for assessing and monitoring browsing impact. (C) 2000 Elsevier Science Ltd. Al l rights reserved.