Study On Ecological Stoichiometric Characteristics Of Desert Vegetation Communities In The Upper Reaches Of The Tarim River

Ecological stoichiometry provides a new idea and theoretical basis for exploring the dynamic changes of the important chemical elements in the physiological and biochemical process of vegetation. Plants in different habitats, after a long period of evolution and adaptation process, form unique ecological stoichiometric characteristics. It is particularly important to study the physiological and ecological processes of vegetation communities in desert environment because the desert vegetation community is controlled by the extreme environment for a long time. The correlation study on the ecological characteristics and environmental factors of the leaves of the desert vegetation communities is of great significance to reveal the community’s demand for nutritional elements like C, N and P and to expose the adaptability and feedback ability of plants to the environment. The research object of this study is the desert vegetation community in the upper reaches of the Tarim River. Studying the relationship between vegetation’s ecological stoichiometry and soil environmental factors by ANOVA, pearson correlation analysis, path analysis and redundancy analysis. The main conclusions were as follows:1. Plant species in the study area were poor. The frequency of Tamarix chinensis in each quadrat was as high as 83.3%. The contents of C, N and P in the plant leaves in the study area are not high, which were(430.48±58.11) mg/g,(15.90±6.15) mg/g and(1.04 ±0.76) mg/g, respectively. C:N, C:P and N:P were(31.14±13.17),(674.08±511.25) and(22.15±13.96), respectively. C content from more to less in different life forms was: herb > subshrub > shrub > arbor. The content of N in subshrub was significantly higher than that of arbor and shrub. P content was the highest in the herb and the lowest in the shrub. C:N ratio, C:P ratio of shrub and N:P ratio of subshrub were higher. The contents of C in gramineous plant was the highest. N content in leguminous plants’ leaves was significantly higher than that in other families. P contents in compositae plants’ leaves was the highest. C:N ratio, C:P ratio of tamaricaceae were the highest. C:N ratio in leguminous plants was more higher.2. The community structure and community diversity index of first bands of community was higher which was closer the river bank of the Tarim River than the other bands of community. Ecological dominance of plant community of third bands of community was higher which was the farthest distance from the river bank was. There were significant correlation among community leaf N content and C:N ratio and N:P ratio. The content of P was significantly correlated with that of C:P ratio and N:P ratio. N:P ratio and C:N ratio and C:P ratio had extremely significant correlation. There was no correlation between C:N ratio, C:P ratio and diversity indexes. Path analysis results show that there was significant positive correlation between community leaf P content and Simpson index, Shannon-Wiener index, Margalef index and Pielou index. The indirect effect of C:P ratio and N:P ratio on community diversity was greatly influenced by P content.3. The relationships between ecological stoichiometric characteristics of the leaf litter and soil environmental factors to be analyzed by traditional statistics and redundancy analysis(RDA). The results show that the importance of soil environmental factors to ecological stoichiometric characteristics of the leaf litter could be arranged as soil water content > Soil P content > soil N:P ratio > soil N content > p H> conductivity > soil C:N ratio > TDS > soil salinity > soil C content > soil C:P ratio. Soil water content, Soil P content, soil N:P ratio and soil N content were extremely significant correlated with ecological stoichiometric characteristics of the leaf litter.