Diversity And Dynamic Distributions Of Beetle Communities In Yeyahu Lake Wetland Nature Reserve, Beijing

During the period of April to October 2006, the community diversity and ecological adaptation of beetles in Yeyahu Lake Wetland Nature Reserve of Beijing was studied by pitfall trap and sweep-net sampling. The community composition, diversity, seasonal and spatial dynamics, similarity of beetle community in different habitats and the characteristic of habitat were analyzed. Furthermore, niche width and niche overlaps of Carabid beetles were also studied. The results are as follows:1. A total of 22400 beetle specimens belonging to 43 families were collected by both sampling methods.And 12336 beetle specimens belonging to 36 families were collected by pitfall trap, including 5 dominant or sub-dominant beetles, i.e. Carabidae, Staphylinidae, Eumolpidae, Curculionidae and Anthicidae. In functional groups, the phytophagous and the predatory were the most abundant in the number of species and individuals (7597 phytophagous beetles, 3568 predatory beetles, 515 coprophagy, 259 scavengers, 380 fungivores and others.). A total of 3578 Carabid beetle specimens belonging to 19 genera and 47 species were collected by pitfall trap. Harpalus, Amara and Pterostichu were the dominant or common genera, including 9,5 and 5 species respectively.2. Comparative analysis of community composition was conducted by Marglef's index (D), Simpson's dominant index (C), Shannon-Wiener diversity index (H') Pielou's eveness index (E), clustering analysis and ordination analysis etc.. The results of cluster analysis and ordination analysis, basing on the composition of total beetles and Carabid beetles, presented obviously differentiation among sampling sites, and the 8 sites could be classified into 4 types. The composition of total beetles and Carabid beetles were more similar in site A, B and C. While site E and F have the degenerate wetland landscape, and the the composition of total beetles and Carabid beetles were more similar. Phragmites australis was the dominant plant of site E, Gand H, but the former was simple in beetle composition.3. Season dynamics of beetles were studied. The period of the initial stage of summer was the fastigium with the number of beetle individuals, while spring was the fastigium with the number of beetle taxa. Predatory beetles lagged behind phytophagous beetles either in the number of taxa or individual. The period of August was the mainly fastigium with the number of species and individual, and the seasonal preference of 19 dominant Carabid beetles were also analyzed.4. The study of beetle landscape dynamics showed that the number of beetle individual reduced from site A to site F. With the similar plant composition, site G and H possessed more beetle individual and taxa than site E. In majority months, the number of Carabid beetle individual and species in 6 sites situated at the west of the levee were reduced with soil humidity from site A to site F. And 19 Caribid beetles were classified into three types, i.e. water closer adaptation, moderate humidity adaptation and extensive adaptation.5. The niche analysis of Carabid beetle showed that many species preferred the late summer, the initial stage of autumn and site A, B or C. Species with more number of individuals in August or September have more extensive seasonal and spatial distributions than others. And the separation of niche was represented at spatial niche, while the seasonal niche overlaps of species collected at spring and late autumn with other species were small.