Stoichiometric Characteristics Of Desert Steppe In Inner Mongolia

As an important constituent for the grassland in Inner Mongolia,desert steppe is of special significance to the production,life and economic development there.The paper studies the plant community and soil stoichiometrical characteristics of desert steppe in the middle of Inner Mongolia(Sunitezuo banner,Suniteyou banner,Siziwang Banner,Darhan Muminggan United Banner),in an effort to provide fundamental basis for the risk monitoring,restoration and rebuilding of desert steppe.The main conclusions are as follows:(1)The desert steppe in the research area is divided into 9 main plant community types by using TWINSPAN classification method in conjunction with CCA sequencing analysis.Amid.the nine plant community types,the Stipa gobica community has the most soil nutrient,while the community of Caragana sinica-Stipa breviflora + Cleistogenes songorica+ Artemisia frigida ringed has the lowest soil nutrient.(2)The organic carbon content in soil has extremely significant positive correlation with total nitrogen,total phosphorus,available nitrogen,C:N and C:P;the total nitrogen and total phosphorus have notable positive correlation with each other,and have extremely significant positive correlation with available nitrogen,C:P and N:P;Total phosphorus and available nitrogen have extremely notable positive correlation with each other,and have extremely significant negative correlation with N:P;Available nitrogen and C:P,N:P have extremely significant positive correlation;C:N and C:P have extremely notable positive correlation with each other,and have extremely significant negative correlation with N:P;C:P and N:P have extremely significant positive correlation;(3)The content of organic carbon in soil has extremely significant positivecorrelation with aboveground biomass;the total nitrogen content in soil has significant positive correlation with aboveground biomass;total phosphorus in soil has extremely significant positive correlation with species richness and aboveground biomass;the available nitrogen have extremely notable positive correlation with litter;available phosphorus in soil has significant positive correlation with species richness;soil C:N has extremely significant negative correlation with species richness;soil C:P and species richness have extremely significant negative correlation;soil N:P and aboveground biomass have significant negative correlation with each other.(4)In community level,the stoichiometric characteristics of aboveground living plants and litters all behave as:N content has extremely significant negative correlation with C:N,and has extremely significant positive correlation with N:P;P content has extremely significant negative correlation with C:P and N:P.The N content of 12 main dominant plants has extremely significant negative correlation with C:N,and has extremely significant positive correlation with N:P;the P content has extremely significant negative correlation with C:P and N:P.(5)The carbon,nitrogen and phosphorus content and their stoichiometry of plants and soil have notable correlation.The total carbon content of plants has significant positive correlation with total nitrogen and organic carbon content in soil.The total phosphorus content of plant has extremely significant positive correlation with the content of available phosphorus in soil;the N:P and C:P of plants all have notable positive correlation with the content of available phosphorus in soil;the total phosphorus content of litter has extremely significant positive correlation with the content of total phosphorus in soil,and has notable negative correlation with the content of available nitrogen,N:P and C:P in soil;the N:P of litter has extremely significant positive correlation with the content of available nitrogen in soil,and C:P of litter has notable positive correlation with the content of available nitrogen,and has notable negative correlation with soil C:P.(6)The five environment factors(longitude,latitude,altitude,average annual precipitation,average annual temperature)all have extremely notable correlation with organic carbon,total nitrogen,total phosphorus,C:N,C:P and N:P of plants.-The explanation rate of average annual precipitation for total nitrogen of plant is 12.5%;the explanation rate of longitude for organic carbon of plant is 11.7%;the explanation rate of average annual air temperature for total phosphorous of plant is 21%;The explanation rate of average annual precipitation for plant C:N is 7.2%;the explanation rate of height above sea level for plant C:P is 13.8%;the average annual air temperature and average annual precipitation all can explain 15.8%of plant's C:P,with explanation rate of average annual precipitation being 12%.(7)The five environment factors all have extremely notable correlation with organic carbon,total nitrogen,total phosphorus,available nitrogen,available phosphorus,C:N,C:P and N:P of soil.The explanation rate of average annual precipitation for total organic carbon of soil is 14.2%;the explanation rate of height above sea level for total nitrogen of soil is 31.1%;the explanation rate of height above sea level for total phosphorous of soil is 8,1%;the explanation rate of average annual precipitation for available nitrogen in soil is 40.3%;the longitude can explain 6.1%of available phosphorous in soil;average annual air temperature can explain 4.8%of soil C:N;latitude can explain 4.8%of soil C:P;average annual precipitation can explain 20.4%of soil N:P.