Asian needle ant (Brachyponera chinensis) and woodland ant responses to repeated applications of fuel reduction methods

Ants (Formicidae: Hymenoptera) are important components of forest ecosystems and can be affected by fuel reduction forest management practices. We assessed the impact of repeated applications of fuel reduction treatments on abundance and diversity of ants within upland mixed-hardwood forests in the Southern Appalachian Mountains in North Carolina, USA. We established three replicate blocks (similar to 56 ha each) and split each block into four fuel reduction treatments, which included prescribed burning (B), mechanical felling (M), a combination of prescribed burning and mechanical felling (MB), and a control (C; i.e., no treatment). We implemented treatments multiple times (two mechanical thinnings and four prescribed burns) over the course of a 15-yr period. Due to tree mortality and resultant canopy gaps from high-severity burns, forest structure was dramatically altered in MB. Over a 3-yr period (2014-2016), we captured 54,219 ants comprised of 23 genera using pitfall and colored pan traps. Prenolepis imparis was the most common ant species collected, and it was significantly lower in abundance in MB than all other treatments. However, the non-native species Brachyponera chinensis was more abundant in MB than all other treatments. Thus, some fuel reduction treatments may have consequences for invasive ant colonization in forests. Most ant taxa did not differ in abundance among treatments, suggesting that some fuel reduction practices may affect some, but not all ant species. Our results indicate that some fuel reduction treatments can alter forest ant communities, thus contributing to changing forest ecosystem dynamics. Monitoring of ants and other bioindicators after repeated rounds of fuel reduction treatments could provide useful knowledge that can be used to help balance forest management and biological diversity.