Short-term response of ground-dwelling arthropods to prescribed fire and mechanical fuel reduction in a Southern Appalachian upland hardwood forest
As part of the multidisciplinary National Fire and Fire Surrogate Study, we used drift fences with pitfall traps to determine how three fuel reduction treatments affected ground-dwelling macroarthropods in the southern Appalachian Mountains of North Carolina. Four experimental units, each 14 ha, were contained within each of three replicate blocks. Treatments were (1) prescribed burning, (2) mechanical felling of shrubs and small trees, (3) mechanical felling burning, and (4) untreated controls. Mechanical understory felling was conducted in winter 2001–2002, and prescribed burning was conducted in March 2003. Mechanical felling burning resulted in greater canopy openness compared with the other treatments as a result of hotter fires and elevated levels of subsequent tree mortality. Burning reduced leaf litter depth in both burned treatments by 80%. We captured 6,776 individual macroarthropods (460 g of dry biomass) within 22 identified orders and 59 identified families. Coleoptera and Hymenoptera were numerically dominant (27.3 and 25.9%, respectively); Lepidoptera larvae also were a dominant component of dry biomass (37%). We found no differences among treatments in the relative abundance or dry biomass of total ground-dwelling macroarthropods or within most orders; Hymenoptera (predominantly Formicidae) dry biomass was greater with mechanical felling burning than with mechanical felling. Total relative abundance and dry biomass were low in spring and higher in late summer. Our results indicate that prescribed burning and mechanical fuel reduction treatments conducted in winter or early spring have little impact on the community composition, relative abundance, or biomass of total arthropods or most arthropod orders and families, at least in the short term. However, because we did not use a killing agent, our trapping method probably undersampled macroarthropods that could climb or fly from traps, and results for those groups should be interpreted cautiously. Our study suggests that the fuel reduction methods studied may be used as a land management tool in upland hardwood forest with little effect on macroarthropod communities or the ground-dwelling arthropod prey base for vertebrates.