The Diversity Of Insects And Soil Animals'Communities Of Riparian Zone In Lingang New Town, Shanghai

Riparian zone is a kind of interface between terrestrial ecosystem and stream ecosystem that material, energy and information transfer into the two different types of ecosystems. The two biological groups-insects and soil animals-are the main parts of riparian biodiversity, up to now, researches on riparian insects mainly focused on three aspects:the life history of insects (terrestrial insects and aquatic insects), the roles of insects in the energy flow of riparian zone, the protection of riparian insect community. Research on soil animal in riparian zone gradually attract researchers' attention as urbanization process growing nowadays.Lingang New Town is a new designed coastal town, as urbanization developing in recent years, most of native vegetation has been replaced by planted vegetation and invasive species of plants. Therefore, study on insects and soil animals in Lingang New Town's riparian zone will much be benefical for us to understand the characters of insects and soil animals'communities in this region well, and then make preliminarily assessment about how urbanization affect biodiversity in the riparian zone.From October2009to September2010, using the methods of sweep net, light trap and sample points investigating the insects and soil animals respectively in Lingang New Town's riparian zone.5typical types of habitats were selected which were wasted land, planted forest, greenland, secondary forest and farmland. Several conclusions were made as follow:(1) Totally7755individuals of insects were collected, belonging to199species,85families and13orders. And the domintant groups were Hemiptera, Hymenoptera, Diptera and Orthoptera. The number and species of aquatic insect accounted for12.1%and11.2%of the total number and species respectively, and the dominant groups were Gerridae and Chironomid larva. In the different habitats, insect number in farmland was the biggest, occupied32.1%, secondary forest was lowest, just occupied11.1%. The impact of different seasons on insects community was significant (F=4.152, P=0.013<0.05), the numbers of insects in spring and autumn were much higher than in summer and winter. From different diversity indexes in different habitats, the biggest Shannon index of insects was planted forest (1.730), second was secondary forest (1.690), green land, wasted land and farmland was1.480, 1.460, and1.420, respectively. Simpson index's variation trend was the contrary to Shannon index. According to analyze diversity index in different seasons, Shannon index of summer reached the highest1.930, and spring was the lowest1.240.(2) The total number of soil animals was1663individuals, belonging to25groups,7classes and2phylums, the dominant groups were Acarina, Collembosla, Psocoptera, Hymenoptera, and Coleoptera. The ratio between Acarina and Collembola was2.160. According to analyze in different habitats, the soil animals' abundance in farmland was bigger than the other habitats, planted forest was the lowest. For the aspect of different seasons, the soil animals in winter was occpied36.1%of total number, autumn was28.0%, summer was21.7%and spring was14.2%, while the difference of soil animals' community in different seasons was not significant (P=0.73>0.05). The soil animals inhabited on the surface of ground obviously, the characters of vertical distribution was D1(0-5cm)>D2(6-10cm)>D3(11-15cm), D1occupied57.3%, D2occpuied27.1%and D3occupied15.6%. The Shannon index of soil animals was the highest in planted forest (1.990), greenland and wasted land were lower, they were1.690and1.400, respectively. On the whole, the changing tendency of Simpson index was contrary with Shannon index and opposite to Pielou index.(3) The densities of insects and soil animals in farmland were the highest,1.705/m2and3483.330/m2, respectively. The density of insect was the lowest in secordary forest, and planted forest held the lowest density of soil animal. The6types of cluster indexes showed that insect community was aggregated distribution, soil animals was homogeneous distribution which much related with the distribution states of food resource in different habitats. The similarity index (Sorenson index) varied among different habitats in the aspects of insects and soil animals' communities, while the values of similarity index were high. The value of Sorenson index about insect communities between planted forest and secondary forest was the highest, gradually declined with wasted land, greenland and farmland, relating greatly with the vegetation types. The Euclidean distance of soil animals between greenland and planted forest was the lowest (34.482), and the Sorenson index was0.834. The results of Sorenson index, cluster analysis and Euclidean distance analysis showed the same trend.(4) According to different feeding habits, insect community could be divided into six groups:phytophagous, predatory, parasitic, saprozoic, omnivorous and flower-visiting. Even though the feeding habits of soil animals in Lingang New Town main could be divided into four parts:predacious, root-eating, saprophagous and mycetophagous, while most soil animals were omnivorous, it was difficult to divide one group of soil animals into a precise feeding habit. The insects and soil animals were the key groups in riparian biodiversity. In this thesis, we primarily analyze food chain of riparian zone in Lingang New Town at the basis of former research.