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

Authors: Campbell, Joshua; GRODSKY, STEVEN - Cornell University; MILNE, MARC - University Of Indiana; VIGUIERA, PATRICK - High Point University; VIGUIERA, CYNTHIA - High Point University; STERN, EMILY - University Of Indiana; GREENBERG, CATHRYN - Forest Service (FS)

Submitted to: Forest Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2022
Publication Date: 2/26/2022
Citation: Campbell, J.W., Grodsky, S.M., Milne, M.A., Viguiera, P., Viguiera, C.C., Stern, E., Greenberg, C.H. 2022. Prescribed fire and other fuel-reduction treatments alter ground spider assemblages in a Southern Appalachian hardwood forest. Forest Ecology and Management. 510. Article 120127. https://doi.org/10.1016/j.foreco.2022.120127.
DOI: https://doi.org/10.1016/j.foreco.2022.120127

Interpretive Summary: Prescribed burns are utilized by forest managers to limit fuel build-up and improve wildlife habitat. However, in areas where human populations have increased, prescribed burns are unpopular due to wildfire risk and smoke. Thus, other management schemes such as understory thinning may be utilized in place of prescribed burns. Spider abundance and diversity are often used to determine the health of ecosystems. We used spider assemblages as a bio indicator of forest health after prescribed burns, understory thinning, and a combination of prescribed burning and understory thinning were accomplished on experimental plots in the Southern Appalachians. Overall, spiders were more abundant and diverse on the management plots compared to control plots (no prescribed burns or understory thinning).

Technical Abstract: Prescribed burns and understory thinnings are forest management practices aimed at reducing fuel loads to lessen wildfire threat in the Southern Appalachians, USA. Spiders play a critical role in forest ecosystems by controlling insect populations and providing an important food source for vertebrates. We used pitfall and colored pan traps to investigate how abundance, species richness, and diversity of spiders differed among three fuel reduction treatments administered repeatedly over a 15-year period and untreated controls. Additionally, we examined how spiders responded to one round (before and after) of fuel reduction treatments. We established treatments 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 and three subsequent burns (MB), and untreated controls (C). Our study period (2014-2016) occurred after multiple prescribed burns and two rounds of mechanical understory removal had occurred. Salticidae and Lycosidae were the two most commonly collected spider families in Southern Appalachian hardwood forests. Generally, we found increased spider abundances within all fuel-reduction treatments compared to controls. Individual spider families and species showed variable responses to treatments, but abundance of several spider families was greater in one or more fuel-reduction treatments than in controls. Additionally, abundance of several spider families and hunting/web building guilds exhibited yearly differences to the last round of fuel-reduction treatments. Overall, our results suggest that changes in the overstory and understory of a forest are important drivers of regional spider abundance and assemblages, and forest management practices that modify forest structure can dramatically alter spider abundance and richness, usually in a positive manner.