The Study On Species Diversity Of Litter-layer Insects In Yeyahu Wetland

Insect is the biggest class group of the animality, regardless of individual quantity, the biomass, the number of species or genes, they hold the very important status. Even some shcolars believe that insect is the master of global biodiversity. Insects are highly sensitive to habitat changes, several groups can be used as indicator of the habitat changes and biodiversity. So the monitor to litter-layer insects has also become an efficient method for monitoring the quality of environment.Yeyahu wetland Nature Reserve, located in the northwest corner of Beijing, is the largest wetland in Beijing, and it is composed of Guanting reservoir belonged to Yanqing and its surrounding beach. It has very important significance to protect the environmental quality of Beijing. And it is also the main station for migratory birds and important habitat for rare waterfowl. However, in recent years because of many reasons the wetlands in Beijing area is faced with decrease of area, loss of biodiversity and many other sentimental questions, so the investigation for the region is significant for the biodiversity conservation.Litter-layer insects communities in four kinds of habitats on the south bank of Guishui River in Yeyahu Wetland Nature Reserve were investigated by using Baraer traps in Aug, 2008. According to the survey records and collection of specimens we calculated the quantity of different habitats and analysized the biodiversity of litter-layer insects, and the relationship between litter～layer insects and vegetation.1. The investigation result: 2459 specimens were collected, and the most abundant groups were Hymenoptera and Coleoptera which account for 38.2% and 30.4% of the total quantity, respectively. In the family level, the largest groups were Formicidae, Carabidae and Gryllidae which account for 37.7%, 25.5% and 12.9% of the total. In addition, the proportions of Scarabaeidae, Staphylinidae , Tenebrionida , Gryllidae ,Calliphoridae and Drosophilidae were larger than 1%. The other 16 families just accounted for 5.2%. Formicidae has the largest number in the Hymenoptera, and Carabidae has the largest number in the Coleoptera. The quantity of litter-layer insects have no obvious changes at 4 different habitats.2. The results of diversity indices and similarity indices analysis: the diversity indices in different habitats shows that habitatⅢ>Ⅱ>Ⅰ>Ⅳ. Jaccard similarity coefficients of HabitatⅡand theⅢare the most similarity.3. The analysis on relationship between vegetation diversity and insect diversity: According to the investigation for four diffident habitats, the insect diversity index was agreement with the vegetation diversity index, the higher plant, higher insect diversity. Analysis show that different functional groups of insects show the selectivity for different habitat, and the distribution of predator insects was close to the bank of the river.4. The relationship between insects' diversity and physical factors: the concentrations of soil organic matter and soil water have a great impact on biodiversity of litter-insects. The impact of inorganic soil is not obvious. There is a significant negative correlation between soil organic matte and insect diversity which is different from that reported by many scholars.