Understanding the pattern of biodiversity is central to conservation biology. The overall aim of this study was to determine the diversity pattern of ground beetles living in temperate forest and adjacent habitats to establish strategies for biodiversity conservation in Korea.
First, assemblage structure and distributional patterns of ground beetles were investigated across forest?farmland transect from two different agro-forested landscapes in Korea. Nine and five sites were selected from Hwaseong (a fragmented landscape) in 2011 and 2012, respectively. Eight sites were selected from Hoengseong (a relatively well-protected landscape) in 2012. Ground beetles were collected by pitfall traps. Species richness in the forest edge of Hwaseong was similar to that in the forest interior. Forest edge species richness in Hoengseong was intermediate. The richness level was between that of the forest interior and that of the surrounding. Non-metric multidimensional scaling based on combined data of Hwaseong and Hoengseong revealed that species composition of ground beetles in the forest edge was similar to that in the forest interior, although some open-habitat species were observed at forest edges. Three characteristic groups (forest specialist, edge associated species, and open-habitat species) of ground beetle species were detected by Indicator Value analysis. In this study, ground beetles showed different response to forest edges in the two agro-forested landscapes, suggesting that edge effect on biota could be influenced by landscape structure.
Second, ground beetles were collected in agro-forested landscape to compare their species richness between conifer plantations and regenerating forests in forest ages throughout Korea. How different functional groups (habitat type, wing morph, and body size) responded to forest type, forest age, patch size, elevation, and geographic location were also determined. A total of 34 species were identified from 3,156 collected ground beetles. Individual-based rarefaction curves showed greater species richness in regenerating forests, especially in 40 to 50 years old forests compared to that in conifer plantations. Stepwise multiple regression analysis and multivariate regression tree showed that patch size and elevation were major predictors of species richness and/or abundance of forest specialists, brachypterous species, as well as large- and medium-sized species. A multivariate regression tree indicated that patch size and elevation were major predictors of assemblage structure. These results suggest that maintaining forest areas may be essential to preserve ground beetle assemblages in agricultural landscapes regardless of forest types.
Finally, community structure of ground beetles among different forest patch sizes according to different forest types at central Korea were compared. In addition, how different functional groups (habitat type, wing morph, and body size) and species responded to patch size, habitat, and geographical variables were determined. A total of 50 species were identified from 17,845 ground beetles in 27 study sites. Individual-based rarefaction curves indicated that higher species richness was found in continuous forests than in forest patches regardless of forest types. Positive relationships were found between forest patch size and species richness of each functional group associated with forest habitat. When all patch size, geographical, and habitat variables were considered simultaneously in multiple regressions, patch size, longitude, latitude, elevation, organic matter, and litter depth were significant predictors of the abundance and species richness of forest specialists, brachypterous, dimorphic, and large-bodied species. Although longitude in multivariate regression tree was the best predictor for 27 study sites, elevation and patch size were also important for further analyses of subgroups. In summary, decreasing patch size is a major factor in the loss of biodiversity for ground beetles. Medium-sized patches regardless of forest types are more suitable for biodiversity conservation than small-sized patches.