Response Of The Leaf Ecological Stoichiometry Characteristics Of Four Common Plant Species To The Elevation On The Central-Eastern Qinghai-Tibetan Plateau

Leaf stoichiometry reflects the adaptation strategies and the mutual feedback relationship between plants and environment.Arising from spatiotemporal differences in water,nutrient and energy balances,variations in leaf stoichiometry(e.g.C,N,and P concentrations,and leaf C/N,C/P,and N/P ratios)are likely to show complex relationships with elevation.A thorough understanding of plants‘ leaf stoichiometry under varying growth conditions will contribute to the understanding of their potential survival strategies under ongoing regional and global changes,thereby allowing appropriate measures to be taken to maintain biodiversity and food safety.The leaf C,N,and P concentrations and its stoichiometry ratio of Agropyron cristatum,Leontopodium leontopodioides,Oxytropis microphylla,Potentilla bifurca at different elevations,including(from 2100 m to 5200 m)on the central-eastern Qinghai-Tibetan Plateau,were investigated,and their ecological adaptability and restricted elements were also discussed for the first time.The results shows:(1)The concentrations of Agropyron cristatum leaf C,N,and P were 410.15 g/kg,23.19 g/kg,and 0.96 g/kg,respectively,and leaf C/N,C/P,and N/P values were 16.93,429.26,and 26.02,respectively.As the altitude rises,the content of leaf C and P decreased first,then increased,while the content of leaf N showed a opposite trend.Leaf C/N decreased first and then increased and then decreased again with altitude.Leaf C/P and N/P increased first,and then decreased with altitude,but there was no significant difference in C/P among different altitudes.The coefficient of variations for leaf C,N,P,C/N,C/P,and N/P were 6%,18%,16%;16%,17%,and 23%,respectively.The concentration of leaf C was neither related to leaf N,P nor leaf C/N,C/P,N/P.The concentration of leaf N was not related to leaf P,C/P,N/P,but was significantly negatively related to leaf C/N.The concentration of leaf P was not related to leaf C/N,but was significantly negatively related to leaf C/N,and N/P.Leaf C/N was not related to leaf C/P.The growth of Agropyron cristatum on the Qinghai-Tibetan Plateau was primarily limited by P.(2)The concentrations of Leontopodium leontopodioides leaf C,N,and P were 407.83 g/kg,23.14 g/kg,1.09 g/kg,respectively,and leaf C/N,C/P,and N/P values were 17.88,416.69,and 23.38,respectively.The content of leaf C decreased first,then increased and then decreased again with altitude,and the content of leaf N and P increased first,then decreased with altitude.Leaf C/P decreased first,and then increased with altitude.There was no significant difference in P and C/P among different altitudes.Leaf C/N increased continuously with altitude,while leaf N/P showed an opppsite trend.The coefficient of variations for leaf C,N,P,C/N,C/P,and N/P were 11%,13%,28%;19%,48%,and 45%,respectively.The concentration of leaf C was not related to N,P,N/P,but was significantly positively correlated with C/N and C/P.The concentration of leaf N was significantly positively correlated with leaf P,but was significantly negatively correlated with C/N,and was not related to leaf C/P,and N/P.The concentration of leaf P was significantly negatively correlated with leaf C/P,N/P,while it was not related to leaf C/N.Leaf C/N was not related to C/P,N/P.Leaf C/P was significantly positively correlated with N/P.The growth of Leontopodium on the Qinghai-Tibetan Plateau was primarily limited by P.(3)The concentrations of Oxytropis microphylla leaf C,N,and P were 378.20 g/kg,34.89 g/kg,1.16 g/kg,respectively,and leaf C/N,C/P,and N/P values were 10.96,361.17,and 33.18,respectively.As the altitude rises,the content of leaf C increased first,then decreased,and leaf N and P decreased first,then increased.Leaf C/N decreased first,then increased.Leaf C/P,N/P increased first,then decreased.Among them,P content and N/P had no difference in different altitudes.The coefficient of variations for leaf C,N,P,C/N,C/P,and N/P were 9%,11%,30%,15%,38%,and 36%,respectively.Leaf C was not related to leaf N,P,C/P,N/P,but was significantly positively correlated with C/N.Leaf N was not related to leaf P,C/P,N/P,but was significantly negatively correlated with C/N.Leaf P was not related to C/N,but was significantly positively correlated with C/P,N/P.Leaf C/N was not related to C/P,N/P.Leaf C/P was significantly positively correlated with N/P.The growth of Oxytropis microphylla on the Qinghai-Tibetan Plateau was primarily limited by P.(4)The concentrations of Potentilla bifurca leaf C,N,and P were 430.76 g/kg,23.53 g/kg,1.32 g/kg,respectively,and leaf C/N,C/P,and N/P values were 18.61,344.68,and 18.68,respectively.The content of leaf C increased first,then decreased with altitude,and the content of leaf N and P decreased continuously with altitude.There was no difference among C/N,C/P,and N/P at different altitudes.The coefficient of variations for leaf C,N,P,C/N,C/P,and N/P were 6%,12%,24%;13%,28%,and 29%,respectively.Leaf C was not related to leaf N,P,C/N,C/P,N/P.Leaf N was not related to leaf P,C/P,N/P,but was significantly negatively correlated with C/N.Leaf P was significantly positively correlated with C/N,C/P,N/P.Leaf C/N was not related to leaf C/P,N/P.Leaf C/P was significantly positively correlated with N/P.The growth of Potentilla bifurca on the Qinghai-Tibetan Plateau was primarily limited by P.Our results suggested that the growth of Agropyron cristatum,Leontopodium,Oxytropis microphylla,Potentilla bifurca on the Qinghai-Tibetan Plateau was primarily limited by P.The intraspecific variation of species stoichiometry was determined by the identity of its environment and species characteristics.