Relationships between tree structures and functional traits of branches and leaves and altitude changes in Prunus armeniaca from Xinyuan

The structures and function of woody plants and the rule of variation of their current-year branches and leaf traits with altitude changes are important contents to grasp the adaptability of vertical distribution. Taking the natural population of P. armeniaca at different altitudes in Xinghuagou, Tuergen Township, Xinyuan County, Yili Kazak Autonomous Prefecture as the research object, a total of 12 plots were set up along the elevation of 1100-1700 m, and the distribution of each 3 plots was used as a gradient. The relationship between the tree structures, current-year branches and leaf functional traits of P. armeniaca and altitude changes was studied in four gradients, and its adaptability to altitude changes was explored. The results indicated that : (1) The population density, DBH and crown width of P. armeniaca were the highest at 1200～1350 m altitude, and reached the peak of tree heights at 1100～1200 m altitude. The population density and crown width of P. armeniaca forests at different altitudes were significantly positively correlated, and the direct effects of altitude on stand density and DBH were the largest and smallest, respectively. (2) With the increase of altitude, the leaf area, leaf length, leaf width and specific leaf area of P. armeniaca decreased gradually, and the leaf thickness increased gradually. The fresh and dry weight of leaves at 1350～1550 m altitude was the largest, and the chlorophyll value at 1200～1350 m altitude was the largest. Each altitude gradient was significantly negatively correlated with leaf length and leaf width, and was significantly positively correlated with leaf thickness. The direct effect of altitude on leaf dry weight was the largest, and the leaf functional traits at different altitudes had different degrees of variation. (3) The current-year branches of P. armeniaca were the longest at 1100～1200 m altitude, and the branch thickness and leaf number were the largest at 1200～1350 m altitude. There was a significant negative correlation between altitude change and branch length, and a significant negative correlation with leaf number. Altitude had the greatest direct effect on branch length, and the degree of branch variation increased with altitude. The tree structure and branch and leaf functional traits of P. armeniaca's natural population were significantly correlated with altitude changes, and the changes of population's growth functional traits indicated its adaptability to different altitude environments.