Species Diversity And The Effect (?) Entironment Of Manas River Valley

The balance of oasis ecosystem is the key question with extensive human activities. Nature plants diversity and the influencing factors, has becoming a main question about vegetation community ecology in desert ecosystem.This paper took Shihezi oasis of Manas River Valley as a case. We using field investigation and laboratory analysis, to climate and soil distribution, to the physiological property of common species, and then to nature vegetation species diversity and its affection by environments, while to niches of the main population and response to environmental change on the soil. Then the thesis provides theoretical and referential guidance for nursing and restoration of nature vegetation. The result shows:1. Average air temperature of month, effective accumulative temperature and rainfall in plant growing season have the territorial distribution.Then soil physicochemical and biological factors have the same change.2. Ecotone communities have the biggest species diversity, where species richness index (R2), Simpson index (D), Shannon-Wianer index (H), Pielou evenness index (Jsw) were 2.19,0.88, 0.96,0.96. And the alluvial fan edge communities have the smallest R2,D,H were 1.57,0.79, 0.81. The relationship between the soil moisture and species diversity index D is significantly negative. And the relationship between the conductivity of soil and species diversity index R2, D are significantly negative. Soil salinity and water is the key factor of plant diversity in this regional.3. Tamarix hispida, Salsola collina and Ceratocarpus arenarius have bigger niche breadth (> 0.5), and are dominate species. And this three palntes have greater proportion of niche similarity with eather other. So they have the similar demands on resources. The remaining is non-dominant species.Vegetation with more niche similarity on level of soil salinity indicated strong salt-tolerant species in the study area.4. The same habitats, Tamarix hispida have the most proline (Pro) and malondialdehyde (MDA) than Karelinia caspica and Salsola collina. Indicating Tamarix hispida cells sensitive to salt stress, and can be produced Pro by the body to regulate cell infiltration beside secreted salt to sustain salt, drought effect. Salsola collina have the least Pro and MDA contents than the other two plants, so Salsola collina may be a kind of salt-exclusion. The Pro and MDA of Karelinia caspica have the significant negative correlation with soil water content, indicating water is the key factor of Karelinia caspica.5. The correlation analysis shows that relationships between the conductivity of soil and all plant diversity indices are not significant in saline area. Plant have the stronger salt-tolerant. The relationship between plant species richness index, evenness index and soil bacterial diversity and the diversity of soil bacteria are influence with each other in saline area.6. This paper has three types bacteria are accelerating seeds germination and one types of restraining. The effect of promoting on seed germination is the strongest in the early germination. And germination rate higher 368%-136% compared to the salt treatment, but later promoted germination will be reduced19.5%-12.9%.The studies indicate natural vegetation is salt-tolerant species. Soil changers induce vegetation changer, and indicate human activities lead saline environment in another point of view.