Conserving threatened Lepidoptera: Towards an effective woodland management policy in landscapes under intense human land-use

Although intensive forestry practices have greatly reduced the biodiversity of native woodland, sympathetic management offers much potential to reverse these negative trends. We tested, using a species-rich group, whether woodland conservation management practices could be of overall benefit, for threatened generalists and specialists alike. Our landscape-scale light-trap experiment compared presence/absence, abundance and species richness of macro-moths at 36 repeatedly sampled sites from six experimental ‘woodland management’ treatments. We recorded 11,670 individuals from 265 species. Our results show that the sheltered, dark, humid, late-successional, high deciduous forest biotope is characterised by high numbers of both individuals and species of moth, and is especially important for some scarce and specialist species of conservation concern. Coppicing and ride widening, which open up dense forest structures, are also valuable woodland conservation tools for macro-moths. Specifically, we show that the mechanism behind the pattern of increased species richness at the woodland-scale involved an increased structural and hence increased micro-climatic and resource diversity for species with an affinity for more open biotopes. This benefits generalist species of conservation concern. Additionally, we show that woodland area is an important factor affecting both moth abundance and species richness in coppiced plots, especially so for nationally declining and severely declining species, suggesting that larger woodlands offer the best opportunities to increase biodiversity through active coppice management. Based on these complementary findings we recommend zoning woodland conservation management practices to take into account the differential value of successional stages for different ecological groups of Lepidoptera.