Variationof Soil Physicochemical And Microbial Properties With Vegetation Change On Interaction In Degraded Steppes In Hulunbeir Of China

Degraded grassland grazing eastern Inner Mongolia herlen basin for the study, comparedthe spatial distribution of different types of functional groups, physical and chemical analysisof soil microbial properties and mechanisms of different grassland degradation degree, whilecarrying out vegetation-Soil Carbon Sequestration studies deposit characteristics, the mainconclusions are as follows:1. Under moderately degraded site, most plants of moisture ecological functional groupsand seed propagation type functional group grow better; Species growing height of lifefunctional groups is biggest under lightly degraded site; In growth functional groups, creepingplants is decreasing with the degradation increasing． From the distribution of abovegroundbiomass perspective, in moisture ecological functional groups, xerophytes occupy adominantposition in moderately and lightly degraded site, but strong xerophytes have obviousadvantages in the severe degraded site; In the life-form functional group, perennial herbs havea significant advantage in different severe degraded site; In growth functional groups,clumping plants mainly distribute in moderately and lightly degraded site and bulbs plantsmainly in severe degraded site． In the light of seed propagation type functional groups,strong propagation type plants mainly live in severe degraded site．2. Soil moisture content，nutrients (organic matter and total nitrogen) concentrations, soilmicroorganism quantity and enzyme activity were all decreased significantly in the degradedsites, whereas both the soil hardness and bulk density showed an opposite trend． The soilmicrobial biomass carbon and nitrogen contents ranged from128～185mg·kg-1and from5.6to13.6mg·kg-1, respectively． The soil dehydrogenase and urease activities negativelycorrelated with soil bulk density but positively correlated with total nitrogen, organic matter,microbial biomass carbon and nitrogen． The aboveground biomass showed significantlypositive correlation with the number of soil bacteria and fungi．3. Species richness of the moderately degraded site was highest, all kinds of speciesprefer living.Under different degradation on grassland, there was certain correlation amongsoil organic carbon matter, the ground biomass, underground biomass and soil microbialbiomass carbon. With the increasing degradation and soil depth, carbon sequestration and soil organic matter reduced but soil inorganic carbon content gradually increased. In addition, theroot-shoot ratio gradually increased. Affected by degradation, soil physical and chemicalproperties and soil quality became poor, thus these accelerated the loss of the soil organicmatter. With the soil microbial biomass carbon as index of soil carbon sequestration degree,carbon sequestration capacity decreased with increase in degradation on grassland.