The effect of prescribed fire on fuel loads, seed germination, and acorn weevils (Coleoptera: Curculionidae) in mixed-oak forests of central Appalachia

Studies have concluded that there is the potential for large-scale conversion of mixed oak forests in the central Appalachians to domination by more mesic species. Specifically, oak regeneration failure in Eastern deciduous forests (EDF) is thought to be connected to fire suppression policies of the last century. The goal of this study was to evaluate the reintroduction of prescribed fire and the use of mechanical thinning into the EDF on fuel loads, seed germination, and acorn weevils (Coleoptera: Curculionidae) with attention to the effects on oak regeneration. Specific objectives of this study were to (1) evaluate surface fire temperatures in the EDF; (2) examine the fine-scale relationship between surface fire temperature and seed survival and germination; (3) examine how fire and/or thinning may directly influence oak seed production; (4) examine the indirect impact of fire and/or thinning on seed quality (effect on seed predators: Coleoptera: Curculionidae - weevils); (5) investigate the composition and structural diversity of fuel beds in the EDF; (6) quantify data on fuel loadings; and (7) provide data for the design of an appropriate fuel model to assist researchers managing fire as a tool to promote oak regeneration. Results from individual studies revealed that fire temperatures were spatially heterogeneous and that below ground temperatures were barely influenced by prescribed fires. Prescribed fire and/or thinning (treatments) did not appear to strongly influence oak seed production or predation rates by weevils in the first growing season. However, during the second season, treatment influence was dramatic. Oaks produced more seed in the thin-burn units and burn units produced a significantly greater number of sound acorns. Treatments significantly reduced mean depth and mass of litter and duff. Fire did not reduce the increased fuel loadings produced by thinning. Due to the mesic nature of the EDF, productivity and decomposition are just as likely as fire to modify fine fuel loads. In general, fire did little to moderate effects on overall fuel loads. Because prescribed fires tend to be less severe than wildland fires, fire prescriptions in the EDF may have to be revised in order to reap some of the ecological effects of fire in these ecosystems.