Study On Vegetation Productivity And Species Diversity Of Plant Community In Different Kinds Of Sandy Land In The East Section Of Kubqi

In this paper soil and vegetation were studied in different kinds of sandy land in the east section of Kubuqi sand dune in ordos plateau in 2008 from soil physics characteristics, species richness, species diversity and vegetation productivity of plant community, the result showed as below:(1) In the first time of growing season, the overground part of perennial vegetation took strong transpiration and water consumption, what led to low soil moisture content, and with the following rainy season, there were litter difference among different sandy lands, but in the late growing season, because of high coverage and surface crust, the atrifical reseeding community got high siol moisture conteng. Soil temperature was affected by many factors, such as air temperatrue, solar radiation, biological activities, etc, but it closely related with soil water. The soil bulk density in atrifical reseeding community was higher than natural community, it showed that the atrifical reseeding plants have stronger sand fixation ability, but in comtrary, high soil bulk density has become obstacle to root activity, and indirectly affected soil hydrothermal condition, furthermore, affected the overground part growing.(2) In different sandy lands, the plant community species richness and diversity were highest, evenness was best, ecological dominaece was lowest and viability was good in semi-fixed sandy land; the fixed snady land as climax community whose structure was stable; the constructive species of atrifical reseeding community throughs natural succession was declining due to their physiological factors, and would be taken place by other species.(3) The difference of plant community overground biomass in different sandy lands was affected by various factors, in which the biomass of semi-fixed sandy land was greatly affected by environmental and biological factors, the fixed sandy land was justy only restricted by environmental factors, but the feedbacek effect to environmental factors of artificial reseeding community was weak. The biomass size was mainly affected by species compositon and presents significant difference.(4) The desert environment is hard, water is mainly limiting factor for plant growing, but the desert plant has many adaptive mechanism. Artemisia ordosia and Hedysarum. fruticosum var. presented strong photosynthetic capacity when the environmental stress was weak and physiological state was best. The photosynthetic capacity of Artemisia ordosia was higher than Hedysarum. fruticosum var.and laeve Astragalus adsurgens CV.'Shadawang', but Hedysarum. fruticosum var.has higher light saturation point, water use efficiency and tolerance capacity.(5) The total root weight and specific root length have significant difference but the total root length has no significant difference, and the root system were all concentrated in the 0～30㎝ soil layer. The fine root (d≤2㎜) took great proportion in total root system and with significantly vertical distribution characteristics. The vertical distribution of root system was greatly affected by soil water content and soil bulk density, but the effect has difference in different sandy lands. The underground biomass size of different plant community was mainly affected by vegetation type.