Studies On The Relationship Between Plant Communities And Soil In Different Types Of Sandy Land In Kubqi Desert

The research on plant communities in fixed sandy land, semi-fixed sandy land and shifting sandy land on Kubqi Desert were conducted in order to analyze the community characteristics of different types of sandy land. Furthermore, the physical and chemical properties of soil and soil respiration were measured in order to study the correlation among plant community, soil properties, soil respiration. The results are as follows:1. From the perspective of species composition, there exists higher similarity between fixed sandy land and semi-fixed sandy land, but lower similarity between these two types with shifting sandy land, indicating great changes has taken place in species composition from shifting sandy land to semi-fixed sandy land. In terms of quantity characteristic, the coverage, height and biomass of Artemisia ordosica in fixed sandy land and semi-fixed sandy land (or Artemisia sphaerocephala in shifting sandy land) determines the characteristic of plant community. However, herbaceous plant affects total density in the lower layer of shrub. In investigated area, the community coverage, density, height and biomass occupies an absolute advantage in fixed sandy land, followed by semi-fixed sandy land, and shifting sandy land has the smallest value.2. Soil bulk density decreased with fixed of sandy land, and increased gradually with soil depth, which reflects that soil bulk density is closely related to plant community. Moreover, this relates to the influence of plant on soil nutrient. There is a significant correlation between aboveground biomass and soil bulk density, soil organic matter, total nitrogen, total phosphorus and total potassium, which reflects the interaction between plant community, soil physical properties and chemical properties. 3. Plant transpiration has an important influence on soil water content. The change of soil water content in fixed and semi-fixed sandy land closely relates with plant growth, especially in rapid growth season when water deep in the ground losing greatly. These results indicate that the strong transpiration of vegetation is the main reason that soil losses water in fixed sandy land and semi-fixed sandy land. While the vegetation is sparse in shifting sandy land, thus evaporation is the main form of water loss.4. Research shows that the organic content in soil include nitrogen, total phosphorus and total potassium, which are increasing with increased degree of immobilization, and fixed sandy land basically identical tendency as the semi-fixed sandy land for the changes in different soil layer, but the big difference happened to shifting sandy land. Differences of nutrient absorption and utilization and the return amount of litter leading to the differences of soil nutrient, moreover, content of total nutrient had significant effect on community biomass and height. Soil available nutrients contents in three types of sandy land exhibited obvious seasonal changes, decreasing the content of available nitrogen, phosphorus and potassium content in summer is the result of interaction of plant with rainwater leaching, The correlation shows that available nitrogen is significantly related with aboveground biomass, but no clear correlation between available phosphorus, potassium and plant community, but more possible relates to eluviations.5. The figure of seasonal dynamic change of Soil respiration rate presented a bell-shape, a maximum in July. The relationship between soil temperature and underground biomass with soil respiration rate reached significant level. Soil respiration reflects the development situation of plant community, the accumulation of biomass will help to improve soil respiration rate, Furthermore, soil respiration can effectively improve the nutrient uptake by plant root, and indirect effect on the community characteristics.