Distribution of carabid beetles among regenerating and natural forest types in Southwestern China

Heterogeneity in species assemblages of carabid beetles was studied between regenerating larch plantations of different forest ages and natural deciduous broad-leaved forests in Southwestern China. Larch plantations that were dominated by the non-native tree species (Larix kaempferi) interspersed with a small proportion of native tree species (L. mastersian) were established after the clear-cutting of the natural deciduous broad-leaved forests. Using pitfall traps, we compared the distribution of carabid beetles in recently planted (5 years old), young (15 years old), mature plantation (45 years old) and adjacent natural deciduous broad-leaved forests (ca. 100 years old). Four replicated plots for each plantation and five replicated transects in natural broad-leaved forest were chosen, and each plot or transect was investigated with four trap locations twice each month during the growing season (May-October) in 2004. Our results showed that species richness, abundance and Shannon diversity were significantly higher in the natural forest than in the regenerating plantations. In addition, these indices were not significantly different in 15- and 45-year-old plantations but were higher than those in 5-year-old plantation. Principal coordinate analysis (PCoA) ordination grouped the carabid assemblages according to forest type and forest age, suggesting that there is a general pattern of recovery after logging. Moreover, indicator species analysis detected significant species associated with forest types and ages. Based on the specificity and fidelity, carabids can be distinguished into six species groups: habitat generalists, generalists in forests with closed canopy, specialists in natural broad-leaved forest, generalists in plantations with closed canopy, young closed canopy larch plantation-associated species and open canopy larch plantation-associated species. Multiple linear regression showed that the depth of leaf litter, the cover of canopy and shrub layer had significant effects in determining richness, abundance and diversity of carabid beetles. Therefore, the regenerating larch plantations, even mature plantations, could not replace the role of the natural deciduous broad-leaved forests in sustaining the diversity of carabid assemblages. Furthermore, establishments of large areas of relatively homogeneous larch plantations may have detrimental long-term effects on the composition and structure of carabid assemblages. Thus, it is important for us to understand the subtle variations in habitat and take appropriate actions for maintaining the invertebrate diversity before the logging of natural forests and establishments of plantations. (c) 2006 Elsevier B.V. All rights reserved.