Catastrophic wind and salvage harvesting effects on woodland plants

Abstract

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. Plot-level data were collected May–June 2016 in areas undisturbed, wind-disturbed, and compound-disturbed (salvage harvested within seven months of an April 2011 EF3 tornado). Disturbance-mediated differences in (1) physical site conditions, (2) woody plant composition and structure, and (3) ground flora (herbaceous and woody plants≤1m in height) were assessed. Multivariate analyses revealed distinct differences in ground flora 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. Unharvested wind-disturbed plots had the greatest diversity of saplings and ground flora, and had indicator species with unique habitat requirements (specialists). Indicator species of compound-disturbed plots were mostly generalists that also had a relatively high frequency and abundance in the other disturbance categories. Reduced plant diversity on compound-disturbed plots was attributed to salvage harvest-mediated reductions in habitat heterogeneity and resource availability. Thus, leaving patches unharvested within salvaged stands is recommended to promote stand-scale plant diversity.