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Predicting variations of evapotranspiration, photosynthesis and water use efficiency in a forest with the change in LAI by the forest management

通过森林管理预测森林蒸散量、光合作用和水分利用效率随 LAI 变化的变化

基本信息

批准号：
15600002
负责人：
OUE Hiroki
金额：
$ 2.43万
依托单位：
Ehime University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

1.Observations in the fieldThe following observations were made at the micrometeorological observational tower, around the center of a coniferous forest catchment that was mainly planted with Japanese cedar and the area of which was 10.7 ha in Ozu.(1)Observation of fluxes by the eddy correlation method and Bowen ratio energy budget method(2)Transpiration and photosynthesis of a single leaf(3)Soil respiration(4)Water balance of the catchment2.ResultsVariations of daily evapotranspiration (ET) and CO_2 flux (CER) in 2005 reached maximum in May - September with minimum in winter. Correlation coefficients between these two fluxes and meteorological conditions, soil water content and four seasons revealed that solar radiation was the first and air temperature was the second factor influencing on the two fluxes. The significance test revealed that the difference between two groups of the fluxes under the condition of air temperature higher than 22 C and lower than 22 C was significant. Yearly ET was 1000 mm and absorption of CO_2 was 27.9t/ha in the forest catchment in 2005.The LAI measured was 4.93 at the observational site. By using a simple model of the canopy transpiration and photosynthesis that consists of leaf transpiration and photosynthesis model and multilayer radiation model within the canopy, variations of canopy ET and photosynthesis with the change in LAI were modeled. The predicted LAI that would make the water use efficiency highest was around 4.

1.野外观测在小津针叶林集水区中心周围的微气象观测塔上进行了以下观测：(1)用涡旋相关法和波文比能量收支法观测通量(2)单叶蒸腾和光合作用(3)土壤呼吸(4)流域水分平衡2.2005年5-9月日蒸散(ET)和CO_2通量(CER)变化最大，冬季最小。这两个通量与气象条件、土壤水分和四季的相关系数表明，太阳辐射是影响这两个通量的第一个因子，气温是第二个因子。显著性检验表明，在气温高于22℃和低于22℃的条件下，两组通量之间的差异显著。2005年林区年蒸散量为1000 mm，吸收CO_2为27.9t/ha，测得观测点LAI为4.93。利用由叶片蒸腾光合作用模型和冠层内多层辐射模型组成的冠层蒸腾光合作用模型，模拟了冠层蒸腾和光合作用随叶面积指数的变化。预测的使水分利用效率最高的叶面积指数在4左右。