Relationship Between Above-ground Functional Traits And Species Diversity And Biomass Of Steppe In Ningxia

Biomass and species diversity are important indicators of ecological function in grasslands.However,the mechanisms related to how plant functional traits respond to changes in environmental gradients and thus affect grassland biomass and species diversity are not clear.Ningxia steppe are located in arid and semi-arid regions,with fragile ecological environments and sensitive to climate change,and have obvious environmental gradients.Therefore,we selected 11 typical sample plots as research objects and measured aboveground functional traits such as plant natural height(PNH),specific leaf area(SLA),leaf carbon,nitrogen and phosphorus content,and leaf carbon stable isotope abundance(δ13C),analyzed the relationships between aboveground functional traits and biomass,species diversity and environmental factors,and finally used structural equation modeling to reveal how environmental factors act on Finally,structural equation modeling was used to reveal the mechanism of how environmental factors act on above-ground functional traits and thus influence steppe biomass and species diversity.The results showed that(1)at the community level,the mean plant natural height(PNH)was 21.78±18.38 cm;specific leaf area(SLA)was 116.48 ± 60.87 cm2/g;carbon stable isotope abundance δ13C was-26.00± 2.45‰;leaf carbon content(LC)was 429.57± 15.40 g/kg;Leaf nitrogen content(LN)was 14.37±4.73 g/kg.Leaf phosphorus content(LP)was 2.26±0.37 g/kg.Leaf C/N ratio(L(C:N))was 32.72±9.63.Leaf C/P ratio(L(C:P))was 194.52±31.29.Leaf N/P ratio(L(N:P)was 6.80±2.74.The coefficients of variation for different types of functional traits differed,and the functional traits associated with competitive resource use were The degree of variation of the functional traits related to competitive use of resources(plant height and nitrogen-phosphorus traits)was higher than that of other traits,with the greatest variation of 84.39%in plant height and 16.09%-40.29%in nitrogen-phosphorus related traits;the lowest variation coefficient trait was carbon stable isotope abundance δ13C of 9.42%.(2)The results of redundancy analysis showed that the environmental factors jointly explained 61.44%of the variance of the community functional traits,and the soil factors influenced the functional traits to a greater extent than the climate factors.(3)The mean values of aboveground biomass,belowground biomass and total biomass of Ningxia steppe were 199.08 g/m2,193.45 g/m2 and 392.54 g/m2,respectively,and the Shannon-Wiener index was 1.92,Simpson index was 0.76,Pielou evenness index was 0.84 and richness index was 11.80,with an overall The overall index of richness was 11.80,and the overall index of meadow steppe>typical steppe>desert steppe,and the species diversity was linearly and positively correlated with biomass.(4)Specific leaf area and leaf carbon to phosphorus ratio were negatively correlated with species diversity,while carbon stable isotope abundance,plant height and leaf phosphorus content were positively correlated with species diversity;carbon stable isotope abundance was significantly negatively correlated with biomass,plant height was significantly positively correlated with aboveground biomass and total biomass,and leaf phosphorus content was significantly positively correlated with belowground biomass.Structural equation modeling indicated that plant natural height(PNH),carbon stable isotope abundance(δ13C),and leaf phosphorus content(LP)were the key traits explaining species diversity and biomass in Ningxia natural steppe.Hydrothermal factors had a greater effect on shaping steppe diversity than soil,while soil affected biomass more.The results of this study can provide a theoretical basis for the response of steppe biomass and species diversity to environmental gradient changes,and provide guidance for the management and utilization of steppe in Ningxia.