Ground beetles as indicators of past management of old-growth forests

Abstract

Old-growth forests are terrestrial ecosystems with the highest level of biodiversity and the main environments for the study of conservation and dynamics of the forest system. In Mediterranean Europe, two millennia of human exploitation deeply altered the structural complexity of the native forests. Some animal groups, including insects, may be used as a proxy of such changes. In this paper we explored the possible effects of forest management on the functional diversity (species traits) of carabid beetle communities. Three old-growth forests of the Sila National Park were sampled by pitfall traps set up in pure beech, beech-silver fir and Calabrian black pine forests. In each forest, five managed vs. five unmanaged stands were considered. Managed sites were exploited until the sixties of the past century and then left unmanaged. More than 6000 carabid specimens belonging to 23 species were collected. The functional diversity in carabid groups is influenced by forest management especially in beech and beech-silver fir stands. Body size, specialized predators, endemic species and forest species were negatively affected by stand management. On the contrary, omnivorous ground beetles populations (or species) with a high dispersal power (macropterous) and large geographic distribution were positively influenced by stand management. In pine forests the old-growth community seems less sensitive to past management and more affected by soil evolution. Soil erosion and disturbance may reduce species diversity of ground beetles. Anyway, the composition of the carabid community shows that 50-60 years of forest restoration are enough for the reconstruction of a fairly diverse assemblage reflecting a “subclimax” situation.

Keywords

• Functional Diversity
• Species Traits
• Forest Management
• Old Growth Forests
• Bio-indicators