PARENT SESSION
Poster Session #39: Disturbance Ecology.
Thursday, August 9, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall

A quarter century of change in old-growth forests.

Runkle, James¹, ¹

ABSTRACT- In 1976-1977 I recorded saplings growing in treefall gaps and canopy trees in several old-growth forests. I resampled in 1983, 1990, and 2000. Here, I detail changes in the southern Appalachians (SA=Great Smoky Mountains NP and Joyce Kilmer Area of Tennessee and North Carolina) and in the Tionesta Area of northwest Pennsylvania (TA). Canopy density decreased (SA: 261 to 255 to 252 trees/ha; TA: 237 to 236 to 215 trees/ha; for 1976/1977 to 1990 to 2000). In SA, hemlock increased in canopy importance; beech decreased; silverbell and sugar maple stayed constant. Larger stems had higher mortality rates than smaller stems. Mortality increased from 0.81%/yr (1976-1990) to 0.97%/yr (1990-2000). In TA, beech increased in canopy importance from 1977 to 1990 then remained constant to 2000; hemlock decreased from 1977 to 1990 then remained constant; red maple increased both times. Canopy mortality increased from 0.6%/yr to 1.1%/yr, primarily in the smaller sizes. In SA gaps, hemlock and sugar maple increased; beech and yellow birch decreased. In TA, beech remained the gap dominant. In the near future I anticipate that a characterization of the SA sites as steady state will still be appropriate. The TA sites will continue to change in response to beech bark disease and other problems such that beech will decline in the canopy even as it continues to dominate the understory.

KEY WORDS: treefall gaps, old-growth forests, canopy turnover, mortality