Forest Response to Large-Scale Disturbances Forests are dynamic entities on a variety of time scales. However, although colonization and regrowth following both small-gap formation and fire have been the subject of much research, forest response to severe wind disturbances has received much less attention. I have studied the damage and vegetation regeneration of several forests following tornado blowdown.
Tornadoes are a major agent of disturbance to forests in the continental interior of North America.
An average of nearly 1000 tornadoes per year occur in the U.S., and although nearly half are very small and weak, a small number do considerable damage to forests. Tornado intensity is rated on a six-level scale, from F0 to F5. Their is a rough increase in tornado size and path length with increasing intensity, so the most powerful tornadoes tend to also be the largest and have the longest damage paths. It is centrally located within the Allegheny National Forest . It was struck by a tornado in May 1985, which destroyed the canopy across nearly 400 hectares.