Accelerated succession following an intense wind storm in an oak-dominated forest

Abstract

Catastrophic wind events often contribute to stand dynamics of central hardwood forests, yet opportunities to study them are limited. As luck would have it, we sampled 54 long-term monitoring plots (0.04ha) on the Shawnee National Forest in southern Illinois prior to an intense 2009 windstorm that swept across the central United States. The sampled plots, which were resampled immediately after the storm, were situated across a gradient of topographic positions. Overstory trees (⩾6.6cmdbh), saplings (⩾1m tall and <6.6cmdbh), and seedlings (<1m tall) were tallied and recorded by species within each plot and used to document post-storm changes in community composition and density. Prior to the storm, species abundance differed among the three strata, and within each strata tree communities were most closely related to slope position and elevation. This relationship did not change after the storm, however there was a shift in species composition of the overstory and seedling strata. Due in part to their overwhelming pre-windstorm abundance, oaks suffered greater losses compared to non-oak species in the overstory strata, accounting for 62% and 53% of all reductions in basal area and stem density, respectively. The lack of understory oak and release of more shade-tolerant species in the understory by the wind storm could potentially accelerate succession. Although wind has likely always played a role in the disturbance regime of central hardwood forests, the effect of wind events has changed with increased fire suppression and threatens the perpetuity of oak-dominated forests in this region.