Impacts of environmental and canopy conditions on the nighttime sap flow of larch plantations in the Liupan Mountains,China  

作　　者：Songping Yu Jianbin Guo Zebin Liu Yanhui Wang Lihong Xu Pengtao Yu Liang He 

机构地区：[1]School of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,People’s Republic of China [2]Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration,Ecology and Nature Conservation Institute,Chinese Academy of Forestry,Beijing 100091,People’s Republic of China

出　　处：《Journal of Forestry Research》2023年第6期1927-1940,共14页林业研究（英文版）

基　　金：funded by the National Natural Science Foundation of China(41971038;U20A2085;32171559;U21A2005);the Fundamental Research Funds of CAF(CAFYBB2020QB004;CAFYBB2021ZW002)。

摘　　要：Nighttime sap flow(Q_(n))is an important physiological activity under which trees manage drought stress.An in-depth understanding of the characteristics of Q_(n)and its response to environmental and canopy conditions are of significance for arid area forest and water management.This study measured daily sap flow(Q_(s))of a Larix principis-rupprechtii plantation in the Liupan Mountains,northwest China during the 2017-2019 growing seasons,and separated Q_(s)into daytime sap flow(Qd)and Q_(n).Meteorological conditions(reference evapotranspiration,ETref),canopy structure(leaf area index,LAI),and soil moisture(relative soil water content,RSWC)were considered as the main biophysical factors affecting Q_(n).The structural equation model and upper boundary line method determined the effects of compound and single factors on Q_(n)The daily mean Q_(n)values during the growing seasons in 2017,2018,and 2019 were 0.024,0.026,and 0.030 mm d-1,accounting for 6.2,11.2,and 10.1%of Q_(s),respectively.Q_(n)at different canopy development phases(leaf expanding,LG;leaf expanded,LD;and defoliation,DF)over three years was LD>LG>DF.Q_(n)increased with increasing ETref,whereas the ratio of Q_(n)to Q_(s)decreased.Q_(n)did not show regular variation in the three-year growing seasons under different soil moisture conditions.ETrefand LAI mainly controlled Q_(n)by affecting Qd,whereas RSWC had no significant effect on Q_(n).Q_(n)had a positive and linear relationship with LAI and a quadratic relationship with ETref.Both explained 40%of variation in Q_(n)Meteorological and canopy conditions are important factors affecting Q_(n)on the semi-humid study site.The application of the Q_(n)model coupled with the impact of ETrefand LAI furthers understanding of the impacts of climate and forest structure change on Q_(n).

关 键 词：Nighttime sap flow Reference evapotranspiration Leaf area index Soil moisture Multifactor impact 

分 类 号：S791.22[农业科学—林木遗传育种]