Impacts of non-native spruce reforestation on ground beetles

Impacts of non-native spruce reforestation on ground beetles were studied. Pitfall catches from recently established (5 years), young (15 years), middle-aged (30 years), old spruce plantation (50 years) and a native beech forest (70 years) were compared. Results indicate that the soil temperature, the pH, the compactness and the CaCO3 content of the soil, the cover of the leaf litter and the herbs and the abundance of the carabids' preys are the most important factors determining the spatial pattern of ground beetles. Deciduous forest specialist species decreased significantly in abundance in the non-native spruce plantations, and they were abundant only in the native beech forest. Ground beetles that overwinter as larvae and the medium and large beetles were also significantly more abundant in the deciduous forest than in the reforested habitats indicating that the environmental regimes are more even and stable in the deciduous forest than in the plantations. Species typical of open habitats, winged and small beetles increased remarkably in abundance in the recently established plantation. They disappeared or declined in density after closure of the canopy layer suggesting the colonization of new habitats and the process of the secondary succession after reforestation. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.