摘要
【目的】探究水源涵养树种树干液流在不同时间尺度的环境调控机制和蒸腾,以提高森林生态系统水源涵养功能评估的准确性,为森林可持续性经营管理提供科学支持。【方法】以北京松山地区乡土树种大果榆为研究对象,2019年和2020年生长季,采用热扩散技术法连续原位观测其树干液流,并同步观测相关环境变量,采用线性和非线性回归法分析树干液流速率(J_(s))对环境的响应。【结果】连续2年生长季内大果榆单位地面面积蒸腾累计分别为334和252 mm,平均每天分别为1.82和1.37 mm。生长期J_(s)变化主要由短波辐射(R_(s))、空气温度(T_(a))、饱和水汽压差(VPD)等环境因子综合调控,J_(s)与R_(s)、T_(a)和VPD均呈显著正线性相关关系,决定系数R2分别为0.93、0.88和0.89,VPD对J_(s)的调控存在阈值(0.9 kPa)。R_(s)、T_(a)和VPD与冠层气孔导度(g_(s))之间存在显著相关关系。昼夜尺度上,J_(s)主要受R_(s)控制,J_(s)日变化滞后R_(s)。【结论】季节与昼夜尺度上J_(s)的调控因子存在一定差异,其环境调控主要通过调节冠层气孔导度进而影响植物树干液流。树干液流对环境因子的敏感性差异及二者日变化的时滞效应能够充分反映出大果榆的耐旱性和环境适应性。
【Objective】This study was carried out to explore the responses of the sap flow and transpiration to the environmental factors at different time scales,and the result here could provide scientific support for formulating appropriate management for forest ecosystem and improve the accuracy of assessment of water conservation function of forest ecosystem.【Method】The thermal diffusion method was used to continuously monitor the sap flow of Ulmus macrocarpa in Songshan,Beijing during the growing season in 2019 and 2020,and the relevant environmental variables were observed simultaneously.Linear and non-linear regressions were used to analyze abiotic control on sap flow.【Result】The cumulative transpiration was 333.85 mm and 252.27 mm in 2019 and 2020,respectively,with daily means of 1.82 mm and 1.37 mm in the two years,respectively.Seasonally,the J_(s)was controlled by shortwave radiation(R_(s)),air temperature(T_(a)),water vapor pressure deficit(VPD).The relationships between J_(s)and R_(s),T_(a)and VPD were significantly and positively linear,with the coefficient of determination R2 being 0.93,0.88 and 0.89,respectively,and with a VPD threshold of 0.9 kPa in growing season.The relationship of J_(s)and R_(s)was stronger(higher R^(2))than that with both T_(a)and VPD in the same month.The daily variation in J_(s)lagged that of R_(s),but preceded that of T_(a)and VPD.The relationships between gs and R_(s),T_(a),and VPD were non-linear correlation,being different from the responses of J_(s)to environmental factors.【Conclusion】There are differences between seasonal and diurnal scale in environmental control mechanism of sap flow,the changes of environmental factors affect the sap flow of plant mainly through inducing stomatal changes.The time lag between J_(s)and environmental factors is explained by the difference in response of canopy stomatal conductance(g_(s))and J_(s)to environmental factors.The time lag and sensitivity of sap flow to environmental factors can reflect drought tolerance and environmental adaptability.These results would help estimation of transpiration under similar environmental conditions and improvment of hydrological model for assessment of water conservation function of forest ecosystem.
作者
张凯
孙艳丽
隗骥超
范雅倩
韩小雪
李林
魏晓帅
李鑫豪
刘鹏
查天山
Zhang Kai;Sun Yanli;Wei Jichao;Fan Yaqian;Han Xiaoxue;Li Lin;Wei Xiaoshuai;Li Xinhao;Liu Peng;Zha Tianshan(School of Soil and Water Conservation,Beijing Forestry University,Beijing 100083;State Key Laboratory of Efficient Production of Forest Resources,Beijing 100083;The Beijing Center for Forest Resource Planning and Monitoring,Beijing 100193;Beijing Lülin Shengyuan Greening Engineering Co.,Ltd,Beijing 102400;Beijing Songshan National Nature Reserve,Beijing 102115)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2023年第7期24-34,共11页
Scientia Silvae Sinicae
基金
国家重点研发计划(2020YFA0608100)
北京园林绿化生态系统监测网络(GJH-2023-027)。
关键词
树干液流
环境变量
辐射
冠层气孔导度
时滞
sap flow
environmental factors
radiation
canopy stomatal conductance
time lag
