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Evaluation of actual transpiration from a forest by means of a long-term monitoring system

通过长期监测系统评估森林的实际蒸腾量

基本信息

批准号：
12680518
负责人：
TANAKA Tadashi
金额：
$ 2.56万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12680518/
关键词：
Japanese red pine forest actual transpiration sap flow Granier method heat pulse method long-term monitoring system midday depression water stress ミズナラ林吸水量と蒸散量可能蒸発量気孔閉鎖アカマツ林地林分蒸発散量昼寝現象季節変化

项目摘要

In the study, a long-term monitoring system was established for evaluating the actual transpiration from a forest. An improved thermal technique called Granier method was applied for monitoring the amount of sap flow. Sap flux measured by the Granier method corresponds well to that by the heat pulse method, and single tree transpiration estimated from the sap flux by the Granier method also corresponds to the value reported in the previous study.To clarify the characteristics of transpiration process and water balance of a tree, continuous measurement of sap flow was conducted in a Japanese red pine forest located at Terrestrial Environment Research Center, University of Tsukuba. The results of the study indicate that the daily maximum transpiration was observed in the early morning and transpiration showed small rates in the afternoon under fine weather condition in the summer. This diurnal change of transpiration was regarded as a midday depression caused by the water stress due to the water up take shortage. The ratio of forest transpiration to evapotranspiration fluctuates seasonally, the maximum and minimum value were found in winter and in summer, respectively. This phenomenon may be attributed to the much amount of shrubs containing deciduous trees which exist in understory. Furthermore, in the study, not only summarize the hydraulic characteristics of stem water in Japanese red pine and oak trees but also summarize the measuring method for stem water storage by the TDR method and the role of forest in the hydrological cycle of a basin.

在研究中，建立了一个长期的监测系统，以评估实际蒸腾从森林。采用一种改进的热分析技术Granier法监测树干液流。采用Granier法测定的树干液流与热脉冲法测定的树干液流基本一致，用Granier法估算的单木蒸腾量与文献报道的结果也基本一致。筑波大学。结果表明，在夏季晴天条件下，日蒸腾量最大值出现在清晨，午后蒸腾量较小。这种蒸腾日变化被认为是由于水分吸收不足而引起的水分胁迫引起的午休现象。森林蒸腾量与蒸散量的比值具有明显的季节波动性，最大值出现在冬季，最小值出现在夏季。这种现象可能是由于林下灌木中含有大量的落叶乔木。此外，还总结了红松和柞树树干水的水力学特性、TDR法测定树干贮水量的方法以及森林在流域水文循环中的作用。