Infrequent, intense wind disturbance is an important factor in northeastern U.S. forests, yet little is known about the early stages of vegetation reorganization, or the processes that facilitate biotic regulation of ecosystem function after such storms. We designed an experiment, based on a simulated hurricane blowdown, to examine the relationship of tree damage patterns to mortality and regeneration, community dynamics, vegetation recovery, and ecosystem processes. In October 1990, selected canopy trees in a 50 × 160 m area within a 75‐yr‐old Quercus rubra–Acer rubrum forest in central Massachusetts were pulled over by a winch, using records from the 1938 hurricane to determine the number of trees and direction of fall. The resulting damage to 65% of trees closely approximated effects of the 1938 storm on New England forests. Damage and mortality varied by tree species and size, indicating the importance of pre‐disturbance forest structure and composition in determining the range and severity of impact. Measurements of vegetation and environment in the experimental area and control indicated that, although the manipulated stand sustained dramatic damage and structural reorganization, resilience of trees and understory vegetation provided tight biotic control of ecosystem processes, including nutrient cycling. Continued leaf‐out and induced sprouting by damaged trees, increased growth by saplings and understory plants, and seedling establishment on disturbed microsites stabilized the microenvironment. Our findings are in contrast to studies of disturbances in which mortality was higher when damaged trees were removed from the site. This suggests that salvage logging following wind disturbance may have serious long‐term implications.

Tip‐up mounds, pits, and other microsites created by hurricanes may promote diversity in many forests by providing opportunities for different species to regenerate. To see if we could detect differences in microsite preference among closely related species, we studied the regeneration of three sympatric Betula species on five types of microsites on experimental mound–pit complexes. Microsites were created by pulling down canopy trees to simulate damage from past hurricanes in southern New England. Seeds were collected in litter traps and experimentally released over mounds and pits to determine effects of microtopography on fine‐scale dispersal patterns. The fate of naturally germinating seedlings was monitored on the disturbed site, and seedlings were also transplanted onto microsites to examine growth patterns, causes of mortality, and leaf‐level physiology. Seed rain onto the disturbed site was abundant and spatially heterogeneous because of scattered residual canopy trees and surviving uprooted trees. Seeds tended to disperse away from vertically oriented surfaces of mounds and to accumulate in pits. Most seedlings germinated on scarified level areas rather than on mounds or in pits, but mounds became more favorable for germination the second year following disturbance. Two fundamentally different types of mortality were observed in transplanted seedlings. Extrinsic factors such as frost heaving, burial by soil and litter, and browsing were dominant on some microsites. Mortality due to these factors occurred primarily during the winter and was unrelated to seedling size. On other microsites, resource limitation (low light levels and lack of water or nutrients) was the major cause of death. Small seedlings were most susceptible to mortality on these microsites, and most deaths occurred during the growing season. White birch (Betula papyrifera Marsh.) exhibited the fastest growth and most flexible photosynthetic response to changing light levels but suffered greatest mortality on shaded microsites. Black birch (B. lenta L.) showed increased leaf area ratio in shaded conditions. Yellow birch (B. alleghaniensis Britt.) was least flexible and grew more slowly than the other species but was best able to survive on shaded microsites. All species attained maximum growth on tip‐up mounds. After three growing seasons, the tallest seedlings reached nearly 3 m above the forest floor, enabling us to predict which individuals would ultimately reach the canopy to complete the regeneration process.

Catastrophic uprooting of forest canopy trees creates mounds, pits, and other microsites that provide opportunities for regeneration of particular species. We measured environmental factors on five types of microsites created by simulated blowdown of a mixed deciduous forest in central New England, United States. We then estimated spatial variation in resource levels and quantified congruence among different resources at each site. Effects of simulated blowdown on light levels and CO 2 concentrations were more pronounced after three years than effects on nitrogen availability and other soil resources. Spatial heterogeneity in light levels and net nitrification rates was greater in the blowdown, but heterogeneities of soil organic matter concentration and net mineralization rates were greater in the undisturbed forest. Availability of nitrate, a limiting resource in most New England forests, was low on mounds and in pits, but high on the vertical portion of forest floor resulting from uprooting of canopy trees. At a spatial scale relevant to seedlings, resource congruence was greater in the undisturbed forest than in the experimental blowdown, primarily because of the effects of blowdown on light levels. Congruence in the blowdown increased with an increase in spatial scale, but congruence in the undisturbed forest was similar at both spatial scales. Seedling growth of two birch species was correlated with light levels and with congruence among soil resources. This study shows that immediate disturbance effects on microtopography and light levels determine recruitment patterns of colonizing species, with changes in soil resource levels influencing later community development. Furthermore, some species appear to respond to resource congruence, which may provide an additional dimension to the regeneration niche.