Short-term effects of a high-severity summer wildfire on conifer forest moth (Lepidoptera) communities in New Mexico, USA

Forest fires in North America are becoming larger in area and burning with higher severity as a result of climate change and land management practices. High-severity, stand-replacement fires can inflict major changes to forest insect communities, potentially extirpating many species through altered post-fire habitat resources. We assessed forest-dwelling macrolepidopteran moth communities in mixed conifer and ponderosa pine forests during the first year after the 2011 Las Conchas fire in New Mexico, USA. We deployed blacklight traps in replicated burned and unburned stands during June, July, and August in 2012. We collected 9,478 individuals, representing 211 species and 8 families. Noctuidae (124 species) and Geometridae (53) comprised the majority of the taxa, followed by Erebidae (21), Sphingidae (5), Notodontidae (3), Lasiocampidae (2), Saturniidae (2), and Drepanidae (1). Moth communities (species composition and abundances) in each forest type (mixed conifer vs. ponderosa pine) were statistically distinguishable, but shared 56.4% (119) of observed species. Overall, compared to unburned forests, post-fire moth communities in both forest types had significantly lower numbers of individuals, species richness and diversity, and lower evenness in ponderosa pine forests. As expected, categorizing moth taxa by larval host plant taxa revealed that reductions of moth populations following fire were associated with the elimination or reduction of available larval host plants (particularly conifers, oaks, and junipers). We predict that future moth community succession will likely parallel the overall transformation from a forested landscape to a montane meadow/grassland ecosystem, with continued reduction in tree-feeding species and increasing dominance by forb/grass-feeding species.

Automated summary

Forest fires in North America are increasing in size and severity due to climate change and land management practices. These fires can have a major impact on forest insect communities, potentially leading to the extinction of many species. A study conducted in New Mexico after a forest fire in 2011 found that moth communities were significantly affected, with lower numbers of individuals, species richness, and diversity in the burned forests compared to unburned forests. The reduction in moth populations was linked to the loss of larval host plants.