PARENT SESSION
Oral Session # 69: Forest Ecology IV: Communities.
Presiding: D Gavin
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 200.
Structure and composition of 70–80 year–old Fraser fir forests on Roan Mountain.
White, David*,1, Walker, Joan1, 1 Southern Research Station, USDA Forest Service, Clemson, SC, USA
ABSTRACT- Roan Mountain and other Southern Appalachian spruce–fir forests have been heavily impacted by the Balsam Wooly Adelgid (Adelgis piceae Ratz.), historical grazing, logging, fires and other disturbances. Roan Mountain is also the only National Forest area where Fraser fir (Abies fraseri(Pursh) Poir) seed and seedlings are harvested for the Christmas tree industry. To address concerns about the condition of fir forests on Roan, forest structure and composition were examined in 2000. Thirteen, 20×20 m permanent plots were established in 70–80 yr–old fir–dominated stands on south–facing slopes (el.1750–1850 m). Tree (≥10 cm d.b.h.) basal area of Fraser fir, red spruce (Picea rubens Sargent), all other species (OTHER), and total dead species (DEAD) averaged 31.5, 11.8, 0.4 and 10.4 m2 ha-1, respectively. Density for these same groups averaged 729, 229, 25 and 340 stems ha-1, respectively. Density of saplings (>1.4 m tall and <10 cm d.b.h.) of fir, spruce, OTHER and DEAD were 1971, 185, 2491 and 852 stems ha-1, respectively. Rubus species accounted for a majority of OTHER stems. Its abundance in 30% of the plots was associated with increased canopy openness. Stand disturbance, measured by canopy openness and tree mortality, varied considerably across plots, with dead trees comprising 4 to 61 % of total (live + dead) basal area. Fir seedling abundance (stems ha-1) of the smallest size class (unbranched) averaged 141,000 and varied from 0 to 350,000. Regression analysis of the smallest size classes of fir seedlings indicated that total dead saplings (+), understory herb cover (+), and total live saplings (-) were significant (p<.01) predictors of seedling abundance. The variation in size class distribution patterns found in this study are similar to the range found in the Great Smoky Mt. NP, where differences were attributed to time since adelgid-induced disturbance events.
Key words: Balsam Wooly Adelgid, Disturbance, Fraser fir, Roan Mountain