Distribution of ground-dwelling beetles （Coleoptera） across a forest-clearcut ecotone in Wolong Natural Reserve, southwestern China

The influence of edge effect on ground-dwelling beetles （Coleoptera） across a forest-clearcut ecotone was studied in Wolong Natural Reserve, southwestern China. During the field research, a total of 30 739 beetles were collected with pitfall traps along transects, which extending 100 m from the edge into the forest interior and 100 m into the clearcut. Of the collection, Carabidae comprised 92%, Staphylinidae 3%, Curculionidae 2%, and Tenebrionidae 2%, and these four families can be considered as abundant groups. Family richness, Shannon diversity and equitability display a significant decrease from forest interior, edge to clearcut. Based on the family composition and abundance, ground-dwelling beetles of the forest interior can be separated from those in the clearcut by Principal coordinate analysis ordination, and beetle assemblages in the forest edge were more similar to forest assemblages than to those found in the clearcut by cluster analysis. Seasonal dynamics of family richness showed a monotone peak in the middle season, with a highest value in the forest interior and a lowest value in the clearcut. Family abundance showed two peaks in the middle season, always with more individuals in the clearcut than in the forest interior or in the edge. Multiple linear regression analyses showed that the cover of shrub and litter were the two most important factors in determining family richness, Shannon diversity, equitability and abundance. Our results show that the forest edge and clearcut have obviously different composition and diversity of ground-dwelling beetles from forest interior at the family level. However, more edges have been formed due to increasing forest fragmentation （clearcutting or logging）, so it is necessary to preserve large and intact forest to protect the diversity of ground-dwelling beetles in Wolong Natural Reserve.We are indebted to Dr Jari Niemel^i and Dr Tibor Magura for constructive suggestions on the experiment and provid- ing important references. We are grateful to Mrs Xiao-Ping Zhou, Jin-Yan Huang, Shi-Qiang Zhou, Yuan-Jun Jiang, Shu-Ming Fan, Guo-You Li and You-Qian Yang （Wolong Natural Reserve, Wenchuan County, Sichuan Province） for assistance in field experiments. This study was supported in part by a State Key Basic Research and Development Plan from the Ministry of Science and Technology of China （G2000046800）, National Natural Science Foundation of China （No. 30570215）, a grant to the senior author （No. D/3684-1） of International Foundation for Sciences