[Hydraulics and non-structural carbohydrate contents of under different environmental conditions in Shenyang City, China].

is an important urban ornamental tree species, but poor growth and damages often occur in urban environments. As a street tree species, the decline and death of is particularly frequent, with the relevant physiological mechanism being unclear. In this study, we compared hydraulic characteristics, non-structural carbohydrate (NSC) contents and health status between trees growing along the streets and those in parks in Shenyang City. The results showed that growing along the streets showed higher degrees of branch and leaf mortality than those growing in the parks. Branches of growing in both conditions showed lower degrees of xylem embolism. Branch hydraulic vulnerable curves of under the two growing conditions also showed no significant difference, with the average being lower than -2.8 MPa. growing along the streets had lower leaf area specific conductivity, smaller tracheid diameter, smaller hydraulic diameter, lower soluble sugar content and total NSC than those growing in parks. Hydraulic failure was not the direct reason for the decline and mortality of growing along streets. Under the more stressed growth conditions along the streets, had smaller tracheid diameters in stems and lower Huber values, which limited the ability of water transport and photosynthetic carbon assimilation at the whole branch level. In addition, in order to deal with more serious stress such as greater heat and drought stresses, might need to invest more NSC to repair damage, which further decreaded NSC contents in branches and increased the risk of carbon imbalance. At the same habitat (street or park), xylem hydraulics and NSC contents of also showed relatively large difference among sampling sites, which reflected large heterogeneity of urban environment for tree growth.