TREEFALL AND RESPROUTING FOLLOWING CATASTROPHIC WINDTHROW IN AN OLD-GROWTH HEMLOCK HARDWOODS FOREST

We surveyed the type of treefall (snapped or uprooted), and for snapped trees the height of break and sprouting tendency, in a catastrophic windthrow in an old-growth hemlock-hardwoods forest. Two-thirds of the 630 trees sampled were uprooted and one-third snapped. Trunk size (diameter at breast height) was more important than species in determining whether trees snapped or uprooted. Tree characteristics interacted with storm meteorology to determine the overall pattern of treefalls. We found that only 25% of the snapped trees sprouted in the four growing seasons after the tornado, and that the tendency to sprout varied significantly among species. Of those snapped trees that sprouted, only 68% were alive at the end of the fourth growing season. In contrast to small gaps in the tropics, where sprouted trees contribute a substantial portion of the post-disturbance canopy, sprouting will be of little importance in the re-establishment of forest in this catastrophic windthrow.