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林业科学 ›› 2020, Vol. 56 ›› Issue (3): 8-20.doi: 10.11707/j.1001-7488.20200302

• 论文与研究报告 • 上一篇    下一篇

欧美杨单株液流昼夜组成及其影响因素分析

孔喆1,陈胜楠1,律江2,陈立欣1,张志强1   

  1. 1. 北京林业大学水土保持学院 北京 100083
    2. 北京市共青林场 北京 101300
  • 收稿日期:2019-05-08 出版日期:2020-03-01 发布日期:2020-04-08
  • 基金资助:
    国家科技支撑计划项目"内蒙古及北京区域节水型城镇景观林培育与管理技术体系研究与示范"(2015BAD07B06-4);北京市高精尖学科生态修复工程学

Characteristics of Populus euramericana Sap Flow Over Day and Night and Its Influencing Factors

Zhe Kong1,Shengnan Chen1,Jiang Lü2,Lixin Chen1,Zhiqiang Zhang1   

  1. 1. School of Soil and Water Conservation, Beijing Forestry University Beijing 100083
    2. Gongqing Forest Farm Beijing 101300
  • Received:2019-05-08 Online:2020-03-01 Published:2020-04-08

摘要:

目的: 分析欧美杨107杨昼夜液流特征,量化夜间液流对整日液流的贡献率,探讨昼夜液流对树形因子和环境因子的响应差异,为深入认识树木水分利用策略对环境的响应机制提供理论依据。方法: 以北京市顺义新城滨河森林公园内的树种欧美杨107杨为研究对象,在样地内选择8株35年生、长势良好的样木,于2018年7—10月采用热扩散探针对样木进行树干液流变化监测,并同步监测环境因子。结果: 1)欧美杨小、中、大径阶的液流速率呈"昼高夜低"单峰曲线,前半夜液流活动比后半夜活跃;2)各径阶整日液流量为39.04~94.96 g·cm-2d-1,夜间液流量为3.34~10.49 g·cm-2d-1,夜间液流对整日液流的贡献率在4.2%~16.2%范围内波动,整日液流量与日间液流量(去除夜间液流的日总液流)差异性达极显著水平(P < 0.01);3)日间和夜间液流对树形因子的响应关系一致,冠幅与昼夜液流呈显著正相关(P < 0.05),对昼夜液流的解释程度分别为80%和77%,树高和胸径对昼夜液流的影响不显著(P>0.05);4)饱和水汽压差(VPD)、太阳总辐射(Ra)、空气温度(T)和风速(Ws)是影响欧美杨整日液流量的主要环境因子;影响日间和夜间液流速率的环境因子存在差异,VPD、RaTWs是影响日间液流速率的主要环境因子,而夜间液流速率主要受VPD和Ws影响;Ws对昼夜液流速率的影响具有两重性,具体表现为白天促进树干液流速率,夜间抑制树干液流速率;日间液流量与夜间液流量极显著正相关(P < 0.01),小、中、大径阶的日间液流量对夜间液流量的解释程度分别为37%、48%和47%。结论: 欧美杨存在明显的夜间液流,估算欧美杨耗水量时,忽略夜间液流会低估日常需水量。液流速率对环境因子的响应存在昼夜差异,估算和模拟树木蒸腾量时,应分日间和夜间考虑环境因子对液流速率的影响。

关键词: 欧美杨107杨, 昼夜树干液流, 树形因子, 环境响应, 夜间液流贡献率

Abstract:

Objective: This study aimed to provide a theoretical basis for understanding the characteristics of water use of trees and the response mechanisms to environment through measuring the characteristics of diurnal and nocturnal sap flow of Populus×euramericana cv. '74/76',quantifying the contribution rate of nocturnal sap flow to the daily sap flow,and investigating the response difference of diurnal and nocturnal sap flow to tree dimensions and environmental factors. Method: In this study,P.×euramericana cv.'74/76' was used as the research object,which is a common afforestation tree species in northern China,The experiment was conducted in the Binhe forest park of Shunyi new city,Beijing. Thermal dissipation (thermal dissipation probe,TDP) technique was used to continuously monitor the sap flow of P.×euramericana cv.'74/76',sunny day data were selected and calculated based on measuremnts of the individual plant of small,medium and large diameter of P.×euramericana cv.'74/76',and simultaneously the data of environmental factors were collected. Result: 1) The sap flow velocity of the small,medium and large diameter of P.×euramericana cv.'74/76' all showed a single peak curve with the diurnal sap flow high and nocturnal sap flow low. The first half of the nocturnal sap flow was more active than the second half. 2) During the period from July to October,the daily sap flow over all diameter classes ranged from 39.04 to 94.96 g·cm-2d-1,and the nocturnal sap flow was between 3.34-10.49 g·cm-2d-1. The contribution rate of nocturnal sap flow to the daily sap flow of all diameter classes was between 4.2% and 16.2%. There was significant difference between the daily sap flow and the diurnal sap flow (difference between the daily sap flow and the nocturnal sap flow from) (P < 0.01). 3) The responses of diurnal and nocturnal sap flow to tree dimention were consistent,and the canopy size was significantly (P < 0.05) correlated with diurnal and nocturnal sap flow in P.×euramericana cv.'74/76',and the interpretation of diurnal and nocturnal sap flow was 80% and 77%,respectively. Tree height and diameter at breast height had no significant effect on diurnal and nocturnal sap flow (P>0.05). 4) On the daily scale,vapor pressure deficit (VPD),global radiation (Ra),air temperature (T) and wind speed (Ws) were the main environmental factors affecting the sap flow of P.×euramericana cv.'74/76'. There were differences in the environmental influence factors influencing diurnal and nocturnal sap flow velocity. VPD,Ra,T and Ws were the main environmental factors affecting diurnal sap flow velocity,while nocturnal sap flow velocity was mainly affected by VPD and Ws. The effect of Ws on diurnal and nocturnal sap flow velocity was two fold,which was characterized by promoting diurnal sap flow velocity and inhibiting nocturnal sap flow velocity. Diurnal sap flow was extremely significantly positive correlated nocturnal sap flow (P < 0.01). The diurnal sap flow of the small,medium and large diameters explained 37%,48% and 47% of the nocturnal sap flow,respectively. Conclusion: There is obvious nocturnal sap flow in P.×euramericana cv.'74/76'. When estimating the water consumption of P.×euramericana cv.'74/76',if the nocturnal sap flow is neglected,the daily water demand of P.×euramericana cv.'74/76' will be underestimated. There is difference in the response of P.×euramericana cv.'74/76' sap flow velocity to environmental factors during the day and night,when estimating and simulating tree transpiration,we should consider the effects of diurnal and noctural environmental factors on sap flow velocity separately.

Key words: Populus×euramericana cv. '74/76', diurnal and nocturnal sap flow, tree factors, environmental response, contribution rate of nighttime sap flow to whole day sap flow

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