Mechanism of Evapotranspiration from Forest Floor based on Soil Moisture Changes and its Evaluation Method

基于土壤水分变化的林地蒸散机理及其评价方法

• 批准号: 10660141
• 负责人: TSUCHIYA Satoshi
• 金额: $ 2.37万
• 依托单位: Shizuoka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10660141/
• 关键词: Evapotranspiration; Soil Column; Soil Moisture; Forest; Richards式; 体積含水率; 土壤水分; 林床面; ソイルカラム; リイルカラム; 土壌水分フラックス

This paper examines possible evaluations on the amount of evapotranspiration separately, based on evaporation experiments with an undisturbed soil column.To evaluate the amount of water movement during infiltrating and drying, experiments were performed by using a Kuroboku column picked out under undisturbed conditions on the forest. In the experiments, the pressure heads changes and water balance of the soil column were measured. In comparison with the measured and evaluated amount of water through the upper and lower boundary, the two were in close agreement. To estimate the surface evaporation and the water uptake by pseudo-root system separately, pressure heads in the undisturbed soil column with inserting pseudo-roots on the side were measured. In consequence, the sum of the decrease of volumetric water content in each layer was in good agreement with the loss in weight of the soil column. Evaporation from the top surface of the column was evaluated as the amount of the decrease o … More f volumetric water content in the 1st layer. Water uptake by pseudo-roots was evaluated as a sum of the decrease of volumetric water content from 2nd to 6th layers of the column. Secondly, evaporation from the top surface obtained by solving Richards' equation with the unsaturated flow analysis, was evaluated as the water flux through the top boundary of the column. Water uptake by pseudo-roots was calculated as the difference in the flux between upper and lower layer at the boundary. The sum of estimated amount of evaporation and water uptake by pseudo-roots was in good agreement with the loss in weight of the soil column. Finally, the unsaturated flow analysis applied to the soil moisture changes measured in the southwest slope of Mt. Fuji. As a result, the transpiration rate was evaluated 1.7 mm/day on the average. The evaporation rate from forest floor was evaluated 1.0 mm/day on the average, and the evapotranspiration rate by trees was estimated 2.7 mm/day by adding transpiration rate and evaporation rate. Less

本文在原状土柱蒸发试验的基础上，分别探讨了对蒸散量的可能评价。为了评估在渗透和干燥过程中的水分运动量，实验采用在未受干扰的条件下在森林上挑选的Kuroboku柱进行。在试验中，测量了土柱的压头变化和水平衡。与测量和评估的通过上、下边界的水量相比，两者非常一致。为了分别估算地表蒸发量和假根系吸水量，在未扰动的土柱中测量了侧面插入假根的压力头。因此，各层体积含水量的减少量与土柱重量的损失量的总和符合得很好。柱顶表面的蒸发量被评价为第一层体积含水量减少的量。伪根的吸水量以第2至第6层柱体含水量减少量的总和来评价。其次，利用非饱和流动分析求解Richards方程得到的顶面蒸发量作为通过塔顶边界的水通量。拟根吸水性计算为边界上、下层通量之差。假根蒸发量和吸水量的估计值与土壤柱重损失的估计值基本一致。最后，将非饱和流分析应用于富士山西南坡土壤水分变化。结果表明，蒸腾速率平均为1.7 mm/d。森林地表蒸腾速率平均为1.0 mm/d，树木蒸腾速率加蒸腾速率估算为2.7 mm/d。少

项目成果

柏原佳明、土屋智、逢坂興宏: "土壌カラムにおける蒸発量と擬似根系による水分吸収量の分離"中森研. 48巻. 191-194 (2000)

Yoshiaki Kashihara、Satoshi Tsuchiya 和 Okihiro Osaka：“土壤柱蒸发与假根系统吸水的分离” Nakamori Lab. 48. 191-194 (2000)