Study On Community Of Spiders In Chongxi Wetland

Spiders are natural enemies of various phytophagous insects. They play a irreplaceable role in ecosystem, as well as in wetland ecosystem. This study was studied in Chongxi Wetland in Yangtze Estuary, and accomplished the first checklist of spiders in Chongxi Wetland. The research focused on (1) the spiders' community structure changing with the elevation variation in tidal marsh, (2) the adaptive feature of three life types spiders in tidal marsh and (3) the difference of spiders' community structure between tidal marsh and lake wetland.Major results of this study are:1. Species composing of spiders in Chongxi WetlandThe study preliminary pinpoint the species composing of spiders in Chongxi Wetland. And the first checklist of spiders in Chongxi Wetland is achieved, which included "Checklist of spiders in Xisha Wteland" and "Checklist of spiders in Mingzhu Lake". The "Checklist of spiders in Xisha Wetland" includes 9 families,21 genera and 33 species. The "Checklist of spiders in Mingzhu Lake" includes 12 families 28 genera and 38 species.2. The community structure variation of intertidal spides along the elevation gradientThe community change of intertidal spides along the elevation gradient was obvious. The quantity of species and individuals decrease with the reduction of elevation, but the Shannon-wiener index and Pielou index doesn't change along the elevation gradient. The maximum of species number and individuals number are present in the forested wetland in high intertidal zone, in where Hylyphantes graminicola, Ebrechtella tricuspidata, Araneus ejusmodi, Pardosa sanmenensis are dominant species. The number of species and individuals is lower in middle intertidal zone. And there are similar number of species and individuals in the forested wetland, the pure reed community and the no reed herb community in middle intertidal zone. The dominant species in the forested wetland in middle intertidal zone includes Hylyphantes graminicola and Mendoza canestrinii; The dominant species in the pure reed community includes Clubiona corrugate and Pardosa sanmenensis; The dominate species in the no reed herb community includes Tetragnatha caudicula and Tetragnatha vermiformis. The number of species and individuals in he new reed community in middle and low intertidal zone border is the lowest. Clubiona corrugate is the dominant species here.3. The changes of spiders of different life types alone the elevation gradient in tidal marshSpiders in Xisha Wetland can be divided into weaving spiders and wandering spiders. And wandering spiders can be further divided into plant wandering spiders and ground wandering spiders. Based on the discrimination, the study analysed the compositiong of spiders of three life types in Xisha Wetland and compared changes of them along the elevation gradient. In Xisha Wetland, the proportion of wandering spiders and weaving spiders is 4:1, and the proportion increases in lower elevation. In the forested wetland in high intertidal zone, the proportion is closed to 1:1 without calculating Hylyphantes graminicola which is the dominant species there.The changes of the species and individuals numbers of different life types spiders are different along the elevation gradient. With the decrease of the elevation, the individuals number of each life type spiders is decrease, especially weaving spiders; The species number of weaving spiders decreased obviously; The species number of plant wandering spiders little changed; And the species number of ground wandering spiders decreased slightly. The dominant species of plant wandering spiders which are the most dominant life types in Xisha Wetland, distribute staggeredly to avoid contention.4. The comparison of spiders community structure feature in tidal marsh and lake wetlandThe difference of spiders community in southbank and northbank of Mingzhu Lake is small. The proportion of weaving spiders and wandering spiders is 1:1. The dominant species include Dolomedes sp., Ebrechtella tricuspidata, Yaginumia sia and Hypsosinga pygmaea.In the analysis of diversity, the Shannon-wiener index of Mingzhu Lake is higher than which in Xisha Wetland, and the Pielou index is similar. In order to avoid the experimental error which is due to different sampling method, the study calculated the hierarchicalare diversity index of Mingzhu Lake and Xisha Wetland. The result of the calculation supported the result of the calculation of community diversity indexes. The diversity of spiders community in Mingzhu Lake is higher than which in Xisha Wetland.The study comparatively analysed the species composition, quantitative distribution and life types composition of spiders in Xisha Wetland and Mingzhu Lake, and ascertained the similarity of spiders community in each kind of wetlands by CLUSTER and MDS. The results show that, except for some species, the difference of species composition and quantitative distribution of spiders community in the two kinds of wetlands is great. The dominant species in Mingzhu Lake is no longer be the dominant species in Xisha Wetland, vice versa. The results of CLUSTER and MDS show that, the spiders community in forested wetland in high intertidal zone is more similar to the community in Mingzhu Lake than the community in middle and low intertidal zone.