摘要
【目的】针对树干边材液流速率(Js)在树干不同方位间的差异及其对估算个体蒸腾量时的影响,本研究兼顾精度与节约成本的估算单株平均液流速率的方法,为单株蒸腾量的估算提供可靠方法和依据。【方法】利用热扩散技术(TDP)在科尔沁沙地樟子松整个生长季期间树干4个垂直方位的Js进行了监测,并对降水、土壤水分等进行了连续、同步的监测。【结果】沙地樟子松大树树干边材相对液流速率(液流速率除以该方位观测期间的最大值,Js/max)具有显著的方位差异(P<0.01),其中以南侧边材的Js/max最高。各方位间Js/max值的相对大小具有个体间差异。土壤水分亏缺能引起各方位Js/max的同步显著降低(P<0.05)。通过对不同方位整树平均液流速率(4个垂直方位的平均值)代表性的比较,确定以树干北侧Js值估算樟子松整树平均液流速率的简化模型(slope=1.015,R2=0.99,P<0.01)。经独立样本的检验,模型精度为0.99。【结论】沙地樟子松不同方位液流速率具有显著差异,且方位间的相对大小存在个体间差异。各方位液流速率间具有高度相关性。以北侧1个方位液流速率的测定就能较可靠地估算科尔沁沙地樟子松大树的平均液流速率。
【Objective】The azimuthal difference of sap flux density is one of the important factors affecting the accuracy of individual transpiration estimation.Because of asymmetry of sap flow in different azimuths,how to simplify the treatment to better estimate the average sap flow rate of a plant will be very important【Method】In this study,the thermal dissipation technique(TDP)was used to continuously and synchronously monitor the sap flux density of the four vertical orientations of the trunk of Pinus sylvestris var.mongolica during the whole growing season in Horqin sandy land,and the precipitation and soil moisture content were also synchronously measured.【Result】The relative sap flux density(the sap flux density divided by the maximum value during this azimuth observation,J s/max)of P.sylvestris var.mongolica had significant azimuthal variation(P<0.01),among which relative sap flux density in south-side(J s/max-S)is the highest.The values of J s/max from four azimuthal directions in a tree showed significant inter-individual differences,and there was no distinct relationship between them.Soil water deficit was able to cause a synchronous and significant decrease in sap flux density of all directions(P<0.05).By comparing the representativeness of the mean sap flux density(the mean value of four vertical directions)of the whole tree in different directions,a simplified model for estimating the mean sap flux density of the whole tree was established with the sap flux density on the north side of the trunk(J s/max-N)(slope=1.015,Adj.R 2=0.99,P<0.01).The model has an accuracy of 0.99 by independent sample testing.【Conclusion】There are significant differences in the sap flux density in different azimuths of P.sylvestris var.mongolica trunk,and the differences also varied in individuals.There is a high correlation among J s/max in different directions.For P.sylvestris var.mongolica grown in sandy land,the average sap flux density of the whole tree can be accurately estimated with the sap flux density measured from the north-side of the trunk.
作者
党宏忠
冯金超
韩辉
Dang Hongzhong;Feng Jinchao;Han Hui(Institute of Desertification,Chinese Academy of Forestry Beijing 100091;Institute of Sandyland Management and Utilization ,Fuxin 123000)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2020年第1期29-37,共9页
Scientia Silvae Sinicae
基金
国家自然科学基金项目(31570704)
中央级公益性科研院所基本科研业务费专项资金(CAFYBB2014MA013)
关键词
液流速率
方位差异
边材
樟子松
科尔沁沙地
sap flux density
azimuthal variation
sapwood
Pinus sylvestris var
mongolica
Horqin sandy land
