关键词: 地表甲虫, 植被, 森林片段化, 物种多样性, 蜂桶寨国家自然保护区

Abstract: The litter-layer beetle species diversity in Fengtongzhai National Nature Reserve (102°48′-103°18′ E，30°42′-30°54′ N) and adjacent areas, Sichuan, Southwest China was surveyed. Four local sites were selected to represent the degree of forest fragmentation and coverage of different vegetation. Fengtongzhai (elevation 1 680-2 080 m) is located in the core of the Nature Reserve and is covered with wellprotected native, mixed, broadleaved forests. Guobayan (elevation 2 280-3 340 m) is a site covered with various native vegetation types, but disturbed by intensive human activities. Mahuanggou (elevation 2 430-2 525 m) represents a site with a well-developed secondary coniferous lantation. Shuangshizhen (elevation 870-1 165 m) is covered with fragmented plantations surrounding by farmlands. Using mainly pitfall traps, we built up 26 plots to investigate how the species diversity of litter-layer beetles was influenced by factors such as forest fragmentation, elevation, slope aspect and habitat differentiation etc. Field collections were conducted from June 29 to July 5, 2001. During field research, a total of 2 338 beetle specimens were captured, of which the family Staphylinidae comprised 39.6%, Carabidae 29.3%, and Tenebrionidae, Curculionidae and Chrysomelidae each more than 5% of the total. These five families can be considered as common in the study area. Of the four local sites selected, Guobayan had the highest individual numbers, richness (S) and diversity (H′). Mahuanggou had the highest evenness (J) and the lowest value of richness. Shuangshizhen had the lowest values of diversity and evenness. Fengtongzhai was much more homogenous in habitat variations and thus did not show any extremes of diversity, evenness or richness. The beetle community in the fragmented forest of Shuangshizhen was very different from those at the other three sites. The community at Mahuanggou was more similar to that in Fengtongzhai than Guobayan. Four main types of vegetation were compared. Coleoptera, Staphylinidae and Carabidae were found to be more abundant in coniferous forest than in mixed broad-leaved forest. Tenebrionidae preferred shrub-land, and Chrysomelidae preferred coniferous forest. Curculionidae had the fewest individuals in bamboo. At Fengtongzhai and Guobayan, species and individuals of Coleoptera and dominant beetle families exhibited an overall tendency of increasing with elevation. In ten plots at Fengtongzhai, the northfacing plots were found to have the greater numbers of individual beetles, richness and diversity than the southfacing ones. Based on these results, weconclude that forest fragmentation, elevation, slope aspect, and vegetation variation (habitat types) influence the species diversity of the litter-layer beetle communities in Fengtongzhai National Nature Reserve. Therefore, for forest protection and restoration in this region, efforts to maintain or restore habitat heterogeneity will help to maintain or increase the species diversity of litterlayer beetles.

Key words: litterlayer beetles, vegetation, forest fragmentation, species diversity, natu re reserve