Effects of catastrophic wind disturbance, salvage logging, and prescribed fire on fuel loading and composition in a Pinus palustris woodland

Abstract

Feedbacks between forest vegetation, forest fuels, and fire are critical to the perpetuation of fire-dependent ecosystems. In Pinus palustris (longleaf pine) woodlands, low-intensity fires facilitate a positive feedback in which highly flammable Pinus needles produced by canopy trees sustain frequent fires. These frequent fires inhibit recruitment of more fire-sensitive species and facilitate P. palustris dominance. Although these relationships are recognized in frequent-fire forests, we do not understand how vegetation-fuels-fire feedbacks may be modified by catastrophic disturbances and subsequent salvage logging in these ecosystems. In this study, we sought to address how the composition of fuelbed components differed between mature, catastrophically wind-disturbed, and salvage-logged sites and how prescribed fire would differentially interact with these fuel complexes. Using a permanent plot network, we quantified total fuel loading and fuel loading by flammability group (seven categories based on flammability characteristics) across the three disturbance treatments before and after operational-scale prescribed fire. For total fuel loading, we found significant interactions between disturbance treatment and time relative to prescribed fire. The fuel complex of mature sites was relatively homogenous, dominated by Pinus needles. Fuels on wind-disturbed and salvaged sites had minor contributions from Pinus needles, but that was somewhat offset by increased contributions by early successional species that have flammability characteristics similar to Pinus needles. The prescribed fire reduced fuel loading across all treatments and homogenized the wind-disturbed and salvage-logged fuel complexes. Although salvage logging resulted in a disparate fuel assemblage, prescribed fire appeared to reduce dissimilarity with the naturally disturbed condition.