The structural organization of a moth community (Lepidoptera) in semi-arid rangelands of central Oregon with respect to fire disturbance and yearly weather variation

Authors: HAMMOND, PAUL - Oregon State University; MILLER, JEFFREY - Oregon State University; Davies, Kirk

Submitted to: Journal of Lepidopterists Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2025
Publication Date: 12/18/2025
Citation: Hammond, P.C., Miller, J.C., Davies, K.W. 2025. The structural organization of a moth community (Lepidoptera) in semi-arid rangelands of central Oregon with respect to fire disturbance and yearly weather variation. Journal of Lepidopterists Society. Volume 79, Number 4. https://doi.org/10.18473/lepi.79i4.a5.
DOI: https://doi.org/10.18473/lepi.79i4.a5

Interpretive Summary: Moths are an important food source for many higher trophic levels in sagebrush communities, however, the effects of fire in sagebrush communities on moths in largely unknown. We investigated the response of moths to a wildfire in southeastern Oregon over two different years. Fire and interannual weather variation had strong effects on the moth community dynamics, which would likely affect higher trophic levels, in particular numerous species of birds and mammals, that depend on them for a food source. This research is of interest to wildlife biologists, rangeland managers, fire ecologists, and other scientists.

Technical Abstract: A moth community of 162 species in semi-desert rangelands of central Oregon was studied over two years with respect to the effects of fire disturbance and seasonal weather variation. This community was comprised of 10 distinct guilds based upon larval foodplants and larval feeding habits. These included guilds based upon woody shrubs such as junipers, sagebrush, rabbitbrush, and bitterbrush, plus native bunchgrasses, general grasses, herbaceous plants, and lichens. Larvae feeding on herbs were further divided into climbing cutworms, soil-surface feeding cutworms, and burrowing cutworms. Fire disturbance had a negative impact on the guilds using woody vegetation and native bunchgrasses, and also the climbing cutworms. General grass-feeders increased in abundance, while soil-surface cutworms were not affected in general abundance. However, individual species exhibited wide fluctuations in abundance due to fire disturbance. Drastic fluctuations were also observed with seasonal weather variation, and some individual species either experienced population explosions or crashes, while other species remained unaffected by weather variation. The lichen feeding guild was mostly absent from the community during the dry year of 2009, but experienced large increases in abundance during the wet year of 2011. In general, the guilds feeding on woody shrubs and herbaceous vegetation all showed large increases in abundance during 2011. However, the geometrid moths of the genus Digrammia were most abundant during 2009, and all showed decreases in 2011. Fire disturbance and interannual weather variation had strong effects on the moth community dynamics, which would likely affect higher trophic levels, in particular numerous species of birds and mammals, that depend on them for a food source.