Study On Desert Vegetation And Its Community Properties In The Outer Space Of Agricultural Development Area, Kelamayi

Desert vegetation in the outer space of oasis is the ecotone between desert and oasis, and is also a part of oasis defending systems. It can holdback desert and has significance in the oasis ecological security. Based on the theory of vegetation ecology, this thesis studies desert Vegetation and its Community properties in the Outer Space of Agricultural Development Area, Kelamayi, Xinjiang including the species elements, the community types, interspecies association and the community structure. The thesis draws to the following conclusions:1. The species category constituted to statistic totally has 119 species of higher plants belonging to 27 families, 90 genera in study area. Among them, Chenopodiaceae and Compositae are the two most dominant families. Most species have drought resistance ability including shrubs, nanoshrubs, therophytes. Herbage plant is dominant in life form. Among them, therophytes and ephemeral plant have a high percentage.2.According to the vegetation classification principle of Chinese , the system of vegetation classify in periphery of development agricultural area of Kelamay was divide into two vegetation types, five formations and eighty associations. The southwest area was divided into Ass. Haloxylon ammodendron, Ass. Haloxylon persicum, Ass. Halostachys belangeriana, Ass. Phragmites communities; the northwest area was divide into Ass. Haloxylon ammodendron+Haloxylon persicum, Ass. Haloxylon ammodendron+ Halostachys belangerian, Ass. Haloxylon ammodendron+Nitraria tangutorum, Ass. Haloxylon persicum and Ass. Tamarix chinensis+Phragmites communities.3. In southwest area, the cover grades relatively accord with the law of the desert vegetation cover. 10~25% is a dominant cover grade and has most distributing area in this area. In northwest area, the cover grades are relatively low, in which 1~5% and 5~10% have relatively large area. 10-25% is main cover grade of southwest and accounts for 8.76% of the northwest area. This images that vegetation of the northwest area is serious degeneration.4. All in all, the species richness and diversity indexes of communities in southwest area are higher than northwest, but even indexes are lower. In northwest area, degradation of desert vegetation not only makes species elements of the communities' variable but also result in change of species diversity. In southwest area, desert plant communities have higher species diversity and richness, but part area comes into being degradation status by the influence of the factor such as landform, water, and salt.5. In study area, the more wide niches of Haloxylon ammodendron and Nitraria roborowskii image that the species have wide distribution and lots of plants and may make good use of resources. Halostachys caspica and Halocnemwn strobilaceum have narrow niches and stricture living space, which illustrates that the species have stronger life in salt habitat.6. In periphery of the Agricultural Development Area, Kelamayi, the whole of interspecies association between the main desert plants is non-association. For desert vegetation in study area, interspecies association being significant reflects that the species request consistently for habitats, and competition is not significant. Non-significant or negative association is that the species reflects differently for habitat.