Delaware Water Gap National Recreation Area: Overstory Tree Composition of Hemlock and Hardwood Forest Stands
Sullivan K, Black B, Mahan CG, Abrams MD, Kim KC, Yahner RH. 1998. Delaware Water Gap National Recreation Area: Overstory Tree Composition of Hemlock and Hardwood Forest Stands. Pennsylvania State University, Environmental Resources Research Institute. University Park, PA
This report documents and compares overstory tree composition in fourteen paired hemlock versus hardwood stands at Delaware Water Gap NRA. Stands were classified as bench, ravine, or mid-slope based on topographic characteristics. In each stand, vegetation was sampled at fixed points along each of three transects running perpendicular to a stream which drained the stand. A ten-factor basal area prism was used to identify trees counted at each sampling point. Also, an increment borer was used to take core samples to estimate the age of each stand. Hardwood stands had a higher species richness than hemlock stands (36 vs. 24 species). Within hemlock stands, the four most abundant hemlock associates were chestnut oak, black birch, northern red oak and northern white oak. Eastern hemlock was present in 86% of the hardwood stands. Percent basal area of hemlock was significantly greater in areas of steep slopes. Bench stands had a significantly lower mean percent basal area of hemlock than either ravine or mid-slope stands. Trees within hemlock stands were significantly older than trees within hardwood stands. Past cutting practices may have reduced the amount of hemlock in the hardwood stands. As succession proceeds, hemlock may become a more dominant component where site conditions are suitable. Ravine and mid-slope sites promote factors such as shallow leaf litter, well-drained soils, and moist microclimates, and appear to have the most suitable factors for hemlock growth. Hardwood stands with a low vulnerability to infestation by hemlock woolly adelgid offer potential for management to increase the hemlock component.
- Type
- Published Report
- Authors
- Sullivan, Kristi; Black, Bryan; Mahan, Carolyn; Abrams, Marc; Kim, K; Yahner, Richard
- Date of Issue
- 1998-09
- Publisher
- Pennsylvania State University, Environmental Resources Research Institute
- Units
- DEWA
- Keywords
- Composition, hardwoods, Hemlock (Tsuga), Monitoring, Overstory, Plant Studies, Research Report, Trees