title: Forest lepidopteran communities are more resilient to shelterwood harvests compared to more intensive logging regimes.
abstract: A common measure of ecosystem resilience is the time course to recovery for a system that has been previously disturbed. The goal of this study was to assess whether forest lepidopteran communities displayed three different forms of resilience following experimental timber harvest. Specifically, I examined whether moth species assemblages returned to pre-logging composition (compositional resilience), species richness (structural resilience), and guild diversity (functional resilience) after forest management. Lepidoptera were sampled from 16 forest stands managed with one of four harvest treatments: no logging, clear-cutting, shelterwood harvests, and group selection harvests. Moths were sampled from all forest stands one year prior to harvest in 2007 and immediately postharvest in 2009-2011. Moth community composition only appeared to be resilient to timber harvest in stands managed with shelterwood methods (15% biomass removed) or in the unlogged stands within managed concession units. Both total species richness and species richness of Quercus-feeding moths also appeared to recover to a near original condition three years post-shelterwood logging. In contrast, moth assemblages in clear-cut stands and group selection stands (80% biomass removed) remained impoverished. Tests of functional resilience suggested that richness of species known to be pollinators was largely unaffected by timber management, and the number of moth species known to feed on herbaceous vegetation doubled in stands logged using group selection methods. Dietary specialists were disproportionately abundant in the unlogged stands postharvest, suggesting that species with more narrow dietary niches have the lowest resilience to timber management. These results suggest that most methods of forest management have short-term negative impacts on woody-plant-feeding Lepidoptera, but that the effects are limited to a few years when the harvest method involves shelterwood cuts. Herbaceous-feeding Lepidoptera appear to quickly colonize stands managed with group selection or clear-cutting, so loss of species richness in stands managed with either of these treatments may be less than predicted based on level of timber being removed. Recovery of moth assemblages in more highly disturbed stands will require longer time periods and techniques such as group selection harvests, where upwards of 80% of the standing bole is removed, may not be consistent with conservation goals.
authors: Department of Environmental Science and Policy, Drake University, Des Moines, Iowa 50311-4505, USA. keith.summerville@drake.edu
authors: Keith S
authors: KS
authors: Summerville
mesh_terms: D000818:Animals; D003247:Conservation of Natural Resources / Q000379:methods*; D017753:Ecosystem; D004784:Environmental Monitoring; D016468:Forestry / Q000379:methods*; D007915:Lepidoptera / Q000502:physiology*; D013997:Time Factors; D014197:Trees