Soil Spatial Heterogeneity And Their Impacts On Changes In Plant Diversity In Tieganlike Transition Zone Between Oasis And Desert

Based on the data obtained from soil physical and chemical characteristics from 81 soil samples collected from 9 soil profiles located in ten monitoring sections Tieganlike transition zone between oasis and desert in the lower reaches of Tarim River,southern Xinjiang,we analyzed the spatial patterns of soil properties using non-parametric method or ANOVA,in additional,Based on the data obtained from 29 plots of natural plant communities in the middle reaches of Tarim River,the paper analyzed the community structure and species diversity. The results showed that:(1)From the oasis to the desert environment gradients,the soil moisture content increases along with the soil layer depth increases gradually,and this kind of change tendency is starts in 50cm place to have the obvious change. The total water-soluble salt content in soil in different soil layers have a significant difference between the direction of the vertical profile of the trend was gradually reduced. The ground water burying depth (average 4.54m) in the soil layer soil's salinity content has the remarkable relevance with below 80cm,the total salt content overall assumes the drop the tendency. Effective nitrogen,phosphorus,potassium content declining trend inflection point in the 50cm soil layer,afterward declining trend flatten out. soil nutrient content of the overall declining trend;soil organic matter and soil total nitrogen,total phosphorus,available nitrogen,available phosphorus was significant correlation,soil total phosphorus and total nitrogen,available nitrogen and total nitrogen, available phosphorus and total nitrogen,total phosphorus, available nitrogen, there are relevant,effective nitrogen and potassium in addition to relevance,the rest of no correlation between the index,and total K with no correlation between indicators.(2)Community structure of the study area relatively simple,low levels of species diversity of plant communities,composed of a single species, in ten sections of Tieganlike transition zone. The relationship between plant species diversity and soil factors was also examined by using grey correlation analysis. Results indicate that the measured soil properties,including the organic matter,total N,and total K varied vertically among different soil layers with exception of the total P,with significant differentiation at 50cm soil depth. Based on soil quality,the lower reaches of Tarim River are generally differentiated between the upper sections and the lower sections,with the content of nutrients in soils of the upper parts being greater than in the lower parts. Along the environmental gradients of the different monitoring sections,plant species diversity indices displayed the same pattern of descending gradient as soil organic matter. Moreover,plant communities showed a change from mixed-species communities to single-species community corresponding to the changes of plant species diversity indices,i.e. from the communities composed of arbor (Populus euphratica),shrub(Tamarix spp)and mixture of herbage to pure Tamarix community. Grey correlation analysis indicates that there exist significant relationships of plant species diversity with soil organic matter,total N,total P,and total K in the 0~50cm soil layer,suggesting that changes in these soil factors could reflect changes in plant species diversity to certain extent in Tieganlike transition zone between oasis and desert in the lower reaches of Tarim River.