Changes in carabid beetle assemblages as Norway spruce plantations age

Several managed native forest stands have been reforested with conifer trees in Europe during recent centuries. These habitat alterations have influenced ground-dwelling invertebrates. We studied carabid beetle assemblages from a native beech forest (70-y-old), and a recently established (5-y-old), a young (15-y-old), a middle-aged (30-y-old) and a mature (50-y-old) Norway spruce plantation by pitfall trapping to explore the effect of reforestation on carabid beetles. The total number of carabid species, and the forest species were highest in the beech forest. The number of open-habitat species was highest in the youngest, relatively open monoculture. Ordination also confirmed changes in carabid composition with change in the studied habitats. Newly proposed forest affinity indices, based on species specificity, fidelity, and on a combination of specificity and fidelity were significantly higher in beech forest than in spruce plantations. We found these affinity indices especially useful in revealing the ecological character of the studied carabid assemblages. Regression analyses showed that leaf litter cover, herbs, shrubs, canopy closure and prey abundance were related to the structure of carabid-beetle assemblages.