南昌3种城市树木液流密度及其环境响应特征OA

[Objective]This study aims to elucidate the water use patterns of major tree species used in cities and their influencing factors to environment,providing theoretical support and technical references for species selection of urban street trees and their water-saving management.[Method]Three tree species,including Camphora officinarum,Phoebe bournei,and Schima superba,are selected in Nanchang to measure their sap flow density(Js)using the heat dissipation probe method,and examine the difference in their sap flow densities on different growth stages and their relationships with environmental factors.[Result]During the fast-growing season between July and September,C.officinarum has the highest Js(71.88 gm-2-1),followed by S.superba(49.94 gm-2-1)and P.bournei(44.24 gm-2-1).For all the three species,Js is significantly higher in the fast-growing season than during the leaf-spreading stage between April and June.Seasonal variation in Js is mainly regulated by solar radiation and vapor pressure deficit(VPD).During the leaf-spreading stage,the sap flow(Js)of S.superba and P.bournei lags behind changes in solar radiation(SR)by 1 hour,while C.officinarum is completely synchronized with SR.However,all the three tree species exhibit significant time-lag effects in Js in response to changes in vapor pressure deficit(VPD);on the leaf expansion stage,sap flow occurs one hour ahead of VPD changes,whereas on the fast-growing stage,sap flow lags behind VPD changes by 2 hours.C.officinarum has a high physiological water consumption and is sensitive to SR,S.superba has low water consumption but is insensitive to environmental responses,and P.bournei has the lowest water consumption and remains unresponsive to environmental changes.[Conclusion]Urban tree species have a higher sap flow density and greater water consumption.Sap flow density of urban trees and its environmental response are determined by tree species and growth period.The fast-growing period is a critical time for irrigation,requiring the comprehensive consideration of the time lapse effect of environmental factors.Hence,adopting differentiated water supply strategies in line with the water response traits of different tree species will help achieve efficient water utilization in urban green spaces.