On the Conservation Value of Second-Growth Forests for Leaf-Litter Inhabiting Beetles

Old-growth forests represent rare and disappearing vestiges of minimally impacted biodiversity, and their preservation has been embraced as an important conservation priority. While second-growth-forests may develop many old-growth features, their value for conservation of arthropod biodiversity is debated. We compare the observed and estimated leaf-litter beetle fauna in four old- and four second-growth fragments of southern Appalachian forest, exploring the extent to which old-growth patches host distinct communities, as reflected by species richness and community composition. Of a total of 310 beetle morphospecies recorded, second-growth sites together hosted 230 species, while old-growth sites hosted 206 total species. Averages over sites were more similar, 95 and 96 species, respectively. Estimates accounting for sampling differences suggested species richness of 279 species for combined second-growth sites versus 264 for combined old-growth sites. Representation by trophic guilds was similar between old- and second-growth sites, suggesting that functional differences concerning these communities are minor. All sites hosted unique species, suggesting that the faunas of second-growth sites may represent more than postdisturbance recolonization by a common regional species pool. Together, these results suggest that, for leaf-litter inhabiting arthropods, old-growth forest fragments are not as uniquely valuable as often assumed, and that the conservation values of older secondary-growth forests in southern Appalachia may also be substantial.