Non-structural Carbohydrates(NSC)are not only utilized as energy sources in plant metabolism, but also as the adaptive mechanisms of plant species in response to the environmental changes.Using the anthrone colorimetric method,we measured the NSC content of leaves from 163 tree species collected from four typical forests,which were temperate needle broad-leaved mixed forest,temperate broad-leaved forest, subtropical evergreen broad-leaved forest,and tropical forest,in order to investigate the spatial patterns of leaf NSC along the latitudinal gradient and to explore the relationships between leaf NSC content and climatic factors(temperature and precipitation)on a large scale.The results showed that:(1)The solubl sugar,starch,and NSC in leaves decreased from north to south.For example,the NSC content of temperate needle broad-leaved mixed forests(170.79 mg/g)>temperate broad-leaved forest(100.27 mg/g)>subtropical evergreen broad-leaved forest(91.24 mg/g)>tropical forest(80.13 mg/g).(2)The soluble sugar, starch,and NSC contents of deciduous and broad-leaved trees were similar among different forests;and the order observed was deciduous trees>evergreen trees and broad-leaved trees>coniferous trees.Moreover, the soluble sugar/starch ratio was increased with latitude increasing(R2=0.85,P<0.01).(3)The contents of soluble sugars,starch,and NSC were negatively correlated with mean annual temperature (MAT)and mean annual precipitation (MAP)in the forests(P<0.001).Specifically,soluble sugars, starch,and NSC decreased as MAT and MAP increased.Our findings provide basic data for the carbon metabolism and adaptive strategies of plant species in forests;and provide new insights into the responses and underlying mechanisms of plant species to future climate changes.