Catastrophic wind and salvage harvesting effects on woodland communities

Compound disturbances may result in novel forest successional and developmental patterns. This study investigated effects of post-wind disturbance salvage harvesting, a unique compound disturbance of which the ecological consequences are unresolved, in fire-restored longleaf pine woodlands of the Alabama Fall Line Hills, a characteristically biodiverse and rare ecosystem. Floristic inventories were developed and plot-level data were collected in areas undisturbed, wind-disturbed, and compound-disturbed (wind + salvage) to compare disturbance-mediated differences in (1) physical site conditions, (2) woody plant composition and structure, and (3) ground vegetation (herbaceous and woody plants ≤ 1 m in height). Multivariate analyses revealed distinct differences in ground vegetation across disturbance categories. Biophysical drivers most correlated with differences in species assemblages included volume of coarse woody debris, sapling density, percent canopy cover, and basal area. Wind-disturbed plots had the greatest species richness and diversity of saplings and ground vegetation, and had indicator species with unique habitat requirements (specialists). Indicator species of compound-disturbed plots were mostly generalists with broad habitat requirements. Reduced species diversity on compound-disturbed plots was attributed to salvage harvest-mediated reductions in habitat heterogeneity. Thus, leaving patches unharvested within salvaged stands is recommended to promote stand-scale plant diversity. Interestingly, regeneration of longleaf pine, the most desirable species in the system, increased with collective disturbance severity. Nonetheless, longleaf pine saplings and seedlings were markedly outnumbered by other species in all disturbance categories, indicating that these woodlands need prescribed fire or other competition reduction measures for recovery toward longleaf pine dominance.