Short-Term Effects of Prescribed Burning on Ant (Hymenoptera: Formicidae) Assemblages in Ozark Forests

Abstract

Prescribed fire is a valuable and effective tool in forest management, and understanding the effects of fire on animal communities is increasingly important for monitoring and conservation. We quantified the short-term responses of leaf litter ants to fire in Ozark oak-dominated forests of Arkansas. We repeatedly surveyed litter ants in replicate burned and unburned sites via Berlese extraction, baiting, and hand collecting 30-170 d postfire. We collected 6,301 ants representing 59 species. Cumulative ant species richness was lower in burned forests than in unburned forests. However, differences in average richness and abundance between treatments were inconsistent over time; lower ant abundance and species richness in burned sites occurred only during the first few months postburn. Ant species composition was very similar between treatments, although some species typically associated within mesic and lowland habitats were found only in unburned forests. We conclude that litter ant communities in Ozark forests, as in other regions, are relatively resilient to the effects of prescribed burning.

Effects of Fire Intensity on Litter Arthropod Communities in Ozark Oak Forests, Arkansas, U.S.A

“…This outcome is generally consistent with other studies that have explored the effects of fire on arthropod communities (e.g., Ahlgren and Ahlgren, 1960;Greenberg and McGrane, 1996;Wikars and Schimmel, 2001;Santos et al, 2008;Pryke and Samways, 2012;Verble and Yanoviak, 2013), although few such studies have specifically focused on short term effects or the potential role of variation in local fire intensity. In addition we observed seasonal increases in insect abundance in these forests, consistent with previous studies in the region (Verble and Yanoviak, 2013). Results of this study reveal strong effects of differences in fire intensity on litter arthropod communities in the short term.…”

“…The effects of fire on Ozark litter arthropods persist for .60 d (Verble and Yanoviak, 2013), which explains the lack of complete faunal recovery (i.e., convergence of treatments with controls) over the short time frame of the current study. Although our expectation that short term community recovery rates would vary with local fire intensity was statistically supported, we did not observe dramatically faster recovery rates for low intensity burns relative to high intensity burns.…”

“…Ozark forests have a long history of frequent low intensity burns, thus it is reasonable to expect that fire has shaped the composition and behavior of litter inhabitants, favoring taxa that can effectively avoid fire or rapidly recolonize burned sites. Related studies on this system showed minimal differences in ant species composition between burned and unburned areas over the short term (Verble and Yanoviak, 2013), and ants appear to be particularly adept at avoiding fire by moving deeper into soil (e.g., Pryke and Samways, 2012). Our assessment of compositional differences was limited to ants, but responses to fire often are highly variable among taxa and functional groups (e.g., Hanula and Wade, 2003), and more detailed studies of other diverse focal taxa (e.g., beetles) may be more informative.…”

“…Arthropods may experience high mortality during even mild fires, and community parameters (e.g., abundance and species richness) are typically reduced immediately post fire (e.g., Ahlgren and Ahlgren, 1960;Swengel, 2001;Wikars and Schimmel, 2001;Santos et al, 2008). Within arthropods, litter inhabiting taxa should be particularly sensitive to the effects of fire (Ahlgren and Ahlgren, 1960;Hanula and Wade, 2003;Philpott et al, 2006;Verble and Yanoviak, 2013); even low intensity burns consume leaf litter, and few litter arthropods are sufficiently mobile to escape advancing flames. However, not all litter burns in a fire, and fire intensity at ground level varies with fuel characteristics at spatial scales corresponding to variation in litter arthropod communities (i.e., 1 m 2 ; Kaspari, 1996a, b).…”

“…Statistically, this prediction would be represented as a significant time*treatment interaction. Based on our prior experience with this system (Verble and Yanoviak, 2013) and similar studies in Australia (Pryke and Samways, 2012), we expected ant abundance and species richness to be minimally affected by fire intensity in the short term (e.g., ,60 d).…”