Dendroecological Analysis of Xeric, Upland, Quercus-Dominated Old-Growth Forest within the Ridge and Valley Province of Maryland, USA

摘要

Mesophytic species invasion and the loss of oaks from previously oak-dominated forest communities are two well-documented changes currently affecting the deciduous forests of the Appalachian Mountains. Several previous assessments of these changes prescribe active management to maintain oak. Currently, historically white oak (Quercus alba) dominated mesic stands documented in both the Allegheny Plateau and Ridge and Valley regions show increasing dominance of mesophytic species such as red maple (Acer rubrum) and black birch (Betula lenta). We describe a unique near-xeric, 72-ha tract of old-growth forest within the Ridge and Valley Region. This upland oak-pine, formerly oak-chestnut community, has maintained oak dominance without silvicultural management, despite being greatly impacted from the loss of American chestnut (Castanea dentata), fire suppression, high deer densities, and European gypsy moth (Lymantria dispar) defoliation. A dendroecological analysis of these 200-year-old stands shows persistence of oak through centuries of documented disturbances. These unmanaged old-growth stands have resisted mesophytic species invasion and therefore may provide insight into future compositional patterns and changes of similar upland and ridgeline forests within the Ridge and Valley. The combination of low site quality of ridgelines and ecological disturbances such as defoliation events, which may act as a moderate basal area reduction, allows oaks to persist and maintain dominance without silvicultural intervention. However, fire is recommended for the maintenance of co-dominant fire-dependent species such as Table Mountain pine (Pinus pungens) and herbaceous diversity along these ridge forests.