Early effects of forest regeneration with selective and small scale clear-cutting on ground beetles (Coleoptera, Carabidae) in a Norway spruce stand in Southern Bavaria (Hoglwald)

摘要

This study investigates the early effects of forest regeneration with selective, and small scale clear-cutting, on ground beetle (Coleoptera, Carabidae) community composition in a homogenous, mature spruce forest in Southern Bavaria (Hoglwald), Germany. Carabid beetles were sampled with pitfall-, emergence-, and window-traps, from 1999 to 2001 during a pre-treatment year, the year of cutting, and the year after cutting. In the spruce stand we found a relatively low species richness with few dominating species. Selective cutting preserved this carabid assemblage. At the clear-cuts carabid species richness increased in the year of cutting, because of the invasion of small open field species, and the persistence of most forest species. Also, number of individuals increased due to higher numbers caught in the window-traps. The first open habitat species appeared just a few months after felling. However, in the next year the numbers of individuals, especially of forest species,were drastically reduced. Also, the number of species decreased, and was just slightly higher than on the control plot (mature stand). According to the DCA (detrended correspondence analysis) forest interior species had the same habitat preferences as net building spiders (Amaurobiidae, Linyphiidae) and other families of beetles (Staphylinidae, Curculionidae). Several groups of open habitat species responded positively on different patches found in the clear-cut: (1) diversity ofground vegetation, respectively coverage of shrubs, (2) favour for moist patterns, and water filled ruts (together with Gastropoda), or (3) low coverage of ground vegetation (together with free hunting spiders, Lycosidae). Different structures side by side (mature forest, selective cutting, open areas) may improve diversity on a forest scale. Small openings can serve as an important retreat for open habitat species. However, if clear-cuts become the dominant element, forest species maybe threatened. With selective cutting species richness of carabids is not improved; however, the remaining forest carabid species may be preserved during the early phase of the regeneration process.