Study On Soil Biological Characteristics And Respiration Characteristics Of Different Plant Communities In Desert Steppe Of Ningxia

As one of the main types of terrestrial ecosystems,desert grassland is of great significance to the study of regional vegetation restoration.In this study,the eight major plant communities of the desert steppe in Yanchi County,Ningxia,were the Artemisia frigidal community(Y),Pennisetum centrasiaticum community(Z),Sophora alopecuroides community(K),Lespedeza potaninii community(N),Stipa breviflora Community(D),Clycyrrhiza uralensis community(G),Leymus secalinus community(L),and Nitaria tangutorum community(B)are the research objects,through the enzyme activity,microbial quantity,microbial biomass carbon,nitrogen,microorganisms of different plant communities The number of functional groups was determined,and the soil microbial functional diversity was determined by Biolog method to reveal the biological characteristics of the community.The dynamic closed air chamber analysis method was used to determine the soil respiration rate,and the seasonal dynamics of soil respiration and its relationship with environmental factors were analyzed.The following main findings are obtained:1.Among the eight communities in the desert steppe of Ningxia,the soil enzyme activities of the Stipa breviflora community were at a high level,indicating that the soil fertility and biological activity of Stipa breviflora community were higher.2.The quantity of soil microorganisms in the Pennisetum centrasiaticum community is higher,and the total amount of microorganisms in the Lespedeza potaninii community is the lowest.In the vertical distribution,the number of microbes and four physiological groups of different plant communities showed a trend of decreasing layer by layer,which partly reflected the existence of surface microbes in desert steppe.3.The soil microbial biomass carbon(MBC)content showed that the soil microbial biomass carbon content of the three soil layers of the Sophora alopecuroides community was significantly higher than that of the other seven communities(P<0.05).The soil microbial biomass nitrogen(MBN)content of Artemisia frigidal community has significant advantages.The soil microbial biomass carbon and nitrogen contents in the three soil layers of the Lespedeza potaninii community were low.The microbial biomass carbon and nitrogen content in the vertical direction showed a decreasing rule of layer by layer.There were significant or extremely significant correlations between soil bacteria,fungi and actinomycetes and soil microbial biomass carbon and nitrogen in different spatial layers of different plant communities in the desert steppe of Ningxia(P<0.05).4.Significant analysis of AWCD values of each community by Biolog method G>Z>D>K>B>L>N>Y,and the AWCD values of Lespedeza potaninii community and Artemisia frigidal community were significantly lower than the other six communities(P<0.01).The soil microbial diversity index of Sophora alopecuroides community and Stipa breviflora community were at a high level,indicating that the microbial diversity level of this community was higher,and the two community ecosystems were more stable than the other six communities.5.8 plant communities soil microbes have the highest degree of utilization of amino acid carbon sources,followed by carboxylic acids.From the analysis of the utilization of 6 types of carbon sources,the utilization rate of the five types of carbon sources except the amine carbon source was the highest in the licorice community,indicating that the soil microbial metabolic activity of the licorice community was the highest.Principal component analysis showed that the carbohydrate and carboxylic acid carbon sources were sensitive carbon sources for microbial community changes in desert steppe plant communities.6.During the test period,the average rate of soil respiration in grassland varied from 0.12 to 0.89 gCO2·m-2·h-1,and the soil respiration rate of 8 plant communities peaked from June to August,and the soil respiration rate of different plant communities in the growing season existed,difference.The soil respiration temperature sensitivity coefficient Q10 of different plant communities G>D>Y>N>B>Z>K>L.The two-factor quadratic function model can account for 75%of the relationship between soil respiration rate and soil moisture temperature.