Study On Ecological Stoichiometry Characteristics Under Different Plant Communities In Southern Area Of Ningxia

Ecological restoration and construction on the loess plateau have got some advances, butthere still exists some issues at the same time, such as natural vegetation recovery was slow,preserving rate, survival rate and ecological benefits of artificial vegetation were all low. Plantcommunities are able to adapt to the surrounding environment, which were the results ofnatural selection for a long time. Meanwhile, plant communities can form certain communitystructures and help to understand the spatial distribution pattern of species and ecologicaladaptability.As one kind of typical representative of the Loess Plateau, ecological environment ofsouthern area of Ningxia ecological environment is very frail. Ecological environment therehave had improved with the implementation of the policy of returning farmland to forest andgrassland. This research was related to the ecological stoichiometry characteristics of soil andplant under different plant communities. Concentration of Carbon(C), nitrogen(N),phosphorus(P) of soil, plant and microbial biomass were measured, which revealed therelationships between plant and soil. This research was benefitial for evaluating the ecologicalbenefits and guiding the ecological reconstruction. The results showed that:(1) Soil oganic carbon and soil total nitrogen of Caragana Korshinski had significantincrease with increasing restored years, but soil total phosphorous had no significanceincrease restored years. Soil C: N ratio decreased and soil C: P ratio, N: P ratio increased withincreasing restored years. Caragana Korshinski leaf, leaf litter and root C, N, P increased andCaragana Korshinski C: N, C: P, N: P ratios decreased. Concentration of C, N, P in Leaf werebigger than that in root. Ratios of root C: N, C: P, N: P were bigger than that in leaf, whichmaybe caused by the special features of Caragana Korshinski. In this research, leaf, leaf litterand root N: P ratio were bigger than16, which indicated P was the main limiting factor ofCaragana Korshinski.(2) Soil microbial biomass C, N, P increased with increasing restored years, while soilmicrobial biomass C: N ratio had no significance difference under different restored years, butsoil microbial biomass C: P, N: P ratios increased with increasing restored years. There weresignificant correlations between soil C, N, P and soil microbial biomass C, N, P, respectively. There were significant correlations between soil N and soil microbial biomass C, N.Concentration of C, N in plant were bigger than concentration of C, N in soil.(3) Concentration of C, N and P in plant was higher than that in soil. Concentration oflive plant C was higher than litter C. Concentration of leaf N, P were bigger than and litter.Concentration of plant C: N, C: P, N: P was bigger than that in soil. Leaf N: P ratio>litter N:P ratio> root N: P ratio. Thyme community N: P ratio> ice grass community N: P ratio> longmiscanthu community N: P ratio> artemisia gmelini community N: P ratio. Concentration ofN, P of thyme community and artemisia gmelini community were bigger than that in ice grasscommunity and long miscanthu community. Concentration of thyme community C, N, P werebigger than that in other three communities, Concentration of C, N, P in artemisia gmelinicommunity were lower than that in other three communities. There were significant positivecorrelations between live plant C and root C concentration. There were correlations betweenlive plant P, litter P and root P concentration. There were positive correlation between litter Nand litter P concentration. There were positive correlation among root C, N and Pconcentration. There were positive correlations between SOC and TN concentration. Therewere positive correlations between soil microbial biomass C: N ratio and soil microbialbiomass C: P ratio, There were positive correlations between soil microbial biomass C: Nratios and soil microbial biomass N: P ratio. In this study, N: P ratios of live plant, litter androot were less than14, which indicated that nitrogen was the main limiting factor of fourdifferent grassland communities.