The Relationship Between Plant Community And Soil Water, Soil Organic Carbon In The Semi-arid Nature Grassland Of Loess Plateau

Vegetation restoration is the key factor and effective way of curbing land degradation toconstruct ecological environment in the Loess Plateau, while soil environmental evolution isone of the dominant contents for ecological effective assessment. To clarify the interactionmechanism between grassland plant communities and soil properties, this thesis focused ontypical samples in main communities of nature grassland in Loess Plateau of Gansu province.Based on field monitoring and analysis in laboratory, the characteristics of communitystructure were studied at different grassland. It primary showed the diverse pattern betweenthe plant species diversity and productivity in the different grassland communities. Byquantitative analysis of soil properties, it revealed the soil properties and the relationshipsbetween soil water and soil organic carbon. Furthermore, studying the correlation of soilwater and soil organic carbon combined with the meadow community structurecharacteristics, it clearly showed the relationships among the meadow community structurecharacteristics, soil water and soil organic carbon of nature grassland in the Loess Plateau.The main results are shown as following:(1) There were significant difference about litter biomass, above-and below-groundbiomass in the four different grassland communities. Gramineae-dominated species of Stipa.bungeana. community and Stipa. bungeana.+Artemisia. community above-andbelow-ground biomass were higher than forbs-dominated species of Reaumuria. communityand Artemisia. community. This suggestd that the gramineae plant promoted the biomassorganic carbon accumulation in the semi-arid grassland. The three kinds of diversity index(Shannon-winner index, evenness, species richness) in the Stipa. bungeana.+Artemisia.community were higher than other three communities. In the sample area scale, it showedsignificantly linear correlation between species diversity and total biomass in the Stipa.bungeana. community and Stipa. bungeana.+Artemisia. community, while there was nosignificant correlation between diversity and total biomass in the Reaumuria. community andArtemisia. community. In the regional scale, the relationships between total biomass andspecies diversity showed significantly positive correlation. (2) It showed significantly advantages of soil physical and chemical properties in thegramineous grassland community. Soil water content of gramineaes-dominated communitieswas higher than that of the forbs-dominated communities. In the0-20cm soil layer, soil pHof the Stipa. bungeana.+Artemisia. community was the smallest in the four grasslandcommunities. It showed significantly difference of soil chemical properties in the differentgrassland community, soil organic carbon content, total nitrogen content, soil organic carbondensity and total nitrogen density in the Stipa. bungeana.+Artemisia. community were allhigher than other three communities. Correlation analysis showed that the diverse patternbetween the soil water content and soil organic carbon in the different grassland communities.Therefore, gramineous as the dominant population of the community played the importantrole to improve the soil water, change the soil porosity and increase soil nutrient content.(3) the community between gramineous-dominanted and soil moisture and soil organiccarbon formed positively feedback regulation mechanism. Further more, it effectivelyimproved the habitat characteristics of soil moisture and soil organic carbon. Results showedthat above-ground biomass and species diversity (Shannon-winner index, species richness)were positively correlation with the soil water contant in the Stipa. bungeana.+Artemisia.community. There were negatively correlation with the soil water content in the Artemisia.community. In the Stipa. bungeana.+Artemisia. community and Stipa. bungeana. community,below-ground biomass and total biomass were significantly correlation with soil organiccarbon. In the Artemisia. community, plant biomass and species diversity showed negativelycorrelation with soil organic carbon. In the regional scale, plant biomass and species diversitywere significantly correlated with soil water content and soil organic carbon in the semi-aridnature grasslands.