A permanent plot study of vegetation and vegetation-site factors fifty-three years following disturbance in centralNew England, U.S.A.

Abstract

Permanent plots, established at the Harvard Forest, Petersham, Massachusetts, U.S.A. in 1940 following the 1938 New England Hurricane, were resampled in order to examine the response of forest understory species to disturbance and to compare responses of overstory trees and understory species. The relationship between species composition and environmental and historical factors was also evaluated. Ordination of plots based on overstory trees and understory species exhibited similar patterns of temporal change following the hurricane. Following complete loss of the canopy, the forest was a mixture of newly colonizing pioneer species (e.g., Prunus pensylvanica, Comptonia peregrina, Fragaria spp., and Hedyotis caerulea), and residual woodland species (e.g., Pinus strobus, Quercus spp., Chimaphila spp., Clintonia borealis, Medeola virginiana and Mitchella repens). Over time, pioneer species declined or disappeared, and woodland species increased. As a result, the modern forest, in terms of both tree and understory species composition, regained some resemblance to the pre-hurricane for-est; however, there was a small group of understory species that did not recover pre-hurricane frequencies (e.g., Cornus canadensis, Mitella diphylla, Polygala paucifolia, Pyrola elliptica, Pyrola rotundifolia, and Tiarella cordifolia). There was evidence that variation in composition and abundance of overstory trees and composition of understory species was related to physical site factors in the pre-hurricane forest and in the older post-hurricane forest (1991), but not in the early regenerating forest. Thus, the hurricane and subsequent salvage operations appeared to relax vegetation-site relationships, but only temporarily.