Response Of Leaf Ecological Stoichiometry Of Potentilla Bifurca To Altitude In Qilian Mountains

The Qilian Mountains is an important climate intersection and sensitive region in Northwest China,the terrain in this region is relatively complex,and the altitude ranges from 2000 m to 5500 m,the differences of hydrothermal elements on the altitude gradient are obvious,which provides a unique opportunity to study the effects of altitude on leaf ecological stoichiometry of plant.Altitude,as a major topographic factor,affects plant adaptability and leaf ecological stoichiometry by affecting the combination of water and heat and soil physical and chemical properties.Studying the interaction between leaf ecological stoichiometry and altitude is essential for understanding nutrient cycling processes,developing biogeochemical models,and predicting ecosystem responses to global change.In this paper,taking Potentilla bifurca(common species,dominant species)in Qilian Mountain as the research object,the characteristics of leaf ecological stoichiometry changes along different altitudes(2400,2800,3000,3200 m)were investigated,and based on the analysis of the relationships between leaf ecological stoichiometry and environmental factors,the dominant factors and mechanisms affecting the leaf ecological stoichiometry of the plant were revealed.The results are as follows:(1)On the entire altitude scale,in the depth of 0-40 cm soil layer,the average values of soil organic carbon(SOC),soil total nitrogen(STN),soil total phosphorus(STP),soil available nitrogen(SAN),soil available phosphorus(SAP),SOC/STN,SOC/STP,STN/STP and soil p H were 19.30 g·kg^-1,2.00 g·kg^-1,0.45g·kg^-1,0.11 g·kg^-1,3.31 mg·kg^-1,9.48,43.00,4.49,8.33,respectively.With the increase of altitude,in the depth of 0-40 cm soil layer,SOC and STN contents first increased,then decreased and then increased,STP content first decreased and then increased,SAN content first remained unchanged,then decreased and then increased,SAP content first decreased and then increased.On the entire altitude scale,with the increase of soil depth,SOC and STN contents decreased,STP content first increased and then decreased,SAN and SAP contents decreased.(2)On the entire altitude scale,the average values of leaf carbon(C),nitrogen(N)and phosphorus(P)contents of Potentilla bifurca were 459.74 g·kg^-1,23.08g·kg^-1and 1.34 g·kg^-1,respectively,and the coefficients of variation were 8.43%,7.37%and 43.50%,respectively;the average values of leaf C/N,C/P and N/P were20.04,535.42 and 26.75 respectively,and the coefficients of variation were11.60%,121.66%and 116.92%respectively.With the increase of altitude,leaf C content first increased and then decreased,leaf N content first increased and then decreased and then increased,leaf P content first decreased and then increased and then decreased;leaf C/N first increased and then decreased,leaf C/P first increased and then decreased and then increased,leaf N/P first increased and then decreased and then increased.Leaf C content was significantly positively correlated with leaf C/N,leaf N content was significantly negatively correlated with leaf C/N,leaf P content was significantly negatively correlated with leaf C/P and N/P,and leaf C/P was significantly positively correlated with leaf N/P.(3)Leaf C content of Potentilla bifurca was positively correlated with soil p H,and negatively correlated with STP content and SAN content;leaf N content was positively correlated with SAN content,SOC/STN and mean annual precipitation(MAP),and negatively correlated with soil p H and mean annual temperature(MAT);Leaf P content was positively correlated with MAP,and negatively correlated with MAT;leaf C/N was positively correlated with soil p H and MAT,and negatively correlated with STP content,SAN content,SOC/STN and MAP;leaf C/P and N/P had no significant correlation with soil or meteorological factors.In conclusion,leaf N/P of Potentilla bifurca was greater than 16,indicating that the growth of Potentilla bifurca was mainly restricted by P.Leaf C,N,P contents and leaf C/N had obvious response to altitude,while the response of leaf C/P and N/P was not obvious to altitude.The dominant factor that affected leaf ecological stoichiometry of Potentilla bifurca was SAN,and the main factors were p H,STP,SOC/STN,MAT,and MAP.