Effects of shelterwood harvest and prescribed fire in upland Appalachian hardwood forests on bat activity

Little is known about the effects that oak forest regeneration treatments consisting of a combination of shelterwood harvesting and prescribed fire have on bats, despite increasing use of these treatments. We quantified changes in bat activity levels in relation to oak forest regeneration treatments consisting of harvesting at 50% and 70% retention levels and prescribed fire in two upland Appalachian hardwood forests in Ohio. We monitored bat activity immediately post-harvest, three growing seasons post-harvest, and after application of prescribed fire to harvested stands before the fourth growing season. Total bat activity levels were higher in thinned and thinned and burned treatments than in unthinned controls in all years, but did not differ between harvest treatment levels immediately post-harvest, three growing seasons post-harvest, or between harvest treatment levels within years. Total bat activity post-prescribed fire changed only in the 50% retention harvest treatment blocks, wherein activity decreased. Activity levels of big brown (Eptesicus fuscus) bats were greater in harvested treatment blocks than controls in all years. Activity levels of eastern red (Lasiurus borealis), and Myotis spp. and tri-colored (Perimyotis subflavus) collectively did not differ among treatment blocks post-fire, but were greater in harvested treatment blocks than controls three growing seasons post-harvest. Community composition was strongly related to vegetation volume, with eastern red bats and Myotis and tri-colored bats displaying positive relationships with clutter in low height strata, and big brown bats displaying a negative relationship with clutter in all height strata. The positive relationship between eastern red and Myotis and tri-colored bats and clutter in low height strata may explain why activity levels of these species decreased post-prescribed fire. Our study suggests that the harvesting component of oak forest regeneration treatments may benefit bats for several years, and that while bat activity levels may decline post-prescribed fire, overall activity levels are nonetheless greater than in unthinned areas.