Prescribed fire and other fuel-reduction treatments alter ground spider assemblages in a Southern Appalachian hardwood forest

Abstract

Prescribed burns and understory thinnings are forest management practices aimed at reducing fuel loads tolessen wildfire threat in the Southern Appalachians, USA. Spiders play a critical role in forest ecosystems bycontrolling insect populations and providing an important food source for vertebrates. We used pitfall andcolored pan traps to investigate how abundance, species richness, and diversity of spiders differed among threefuel reduction treatments administered repeatedly over a 15-year period and untreated controls. Additionally, weexamined how spiders responded to one round (before and after) of fuel reduction treatments. We establishedtreatments within the 15-year period as follows: mechanical understory removal (twice; M), prescribed burning(four times; B), mechanical understory removal followed one year later by high-severity prescribed burns andthree subsequent burns (MB), and untreated controls (C). Our study period (2014–2016) occurred after multipleprescribed burns and two rounds of mechanical understory removal had occurred. Salticidae and Lycosidae werethe two most commonly collected spider families in Southern Appalachian hardwood forests. Generally, wefound increased spider abundances within all fuel-reduction treatments compared to controls. Individual spiderfamilies and species showed variable responses to treatments, but abundance of several spider families wasgreater in one or more fuel-reduction treatments than in controls. Additionally, abundance of several spiderfamilies and hunting/web building guilds (webs built for hunting purposes or defense) exhibited yearly differencesto the last round of fuel-reduction treatments. Overall, our results suggest that changes in the overstory andunderstory of a forest are important drivers of regional spider abundance and assemblages, and forest managementpractices that modify forest structure can dramatically alter spider abundance and richness, usually in apositive manner.

Citation

Campbell, Joshua W.; Grodsky, Steven M.; Milne, Marc A.; Vigueira, Patrick; Vigueira, Cynthia C.; Stern, Emily; Greenberg, Cathryn H. 2022. Prescribed fire and other fuel-reduction treatments alter ground spider assemblages in a Southern Appalachian hardwood forest. Forest Ecology and Management. 510(1–3): 120127-. https://doi.org/10.1016/j.foreco.2022.120127.