We tested how abundance shifts in lepidopteran species might impact two different aspects of moth community structure within managed forest stands of Morgan-Monroe State Forest, Indiana.
Significant changes in species abundance and species richness were observed post-harvest. Sudden eruptions in abundance, however, were not observed at the scale of the regional forest moth metacommunity. The form of the species-abundance distribution within most forest stands did not deviate from the best-fit log-normal model across all three sampling years. Abundance shifts thus appeared to be spatially extensive, low density events.
Frequency of stands occupied by early seral moths increased significantly post-harvest. Several species with larvae known to be row crop or forage pests were widespread throughout Morgan-Monroe State Forest (Ostrinia nubilialis, Hypsopygia costalis, Noctua pronuba, Helicoverpa zea) 2 years post-logging. Potential canopy defoliators were negatively affected by time since harvest even in unmanaged stands suggesting that outbreaks may not be expected as a consequence of harvest disturbance.
This suggests that pre-harvest abundance is not a good predictor of a species' resilience to forest management. Importantly, weather-related stochastic changes in abundance might obscure forestry effects.