Experimental study on utilization of remote sensed data for assessing ecophysiological condition of vegetation

为了建立利用遥感技术评价植被生理生态条件的方法，通过野外和室内试验，研究了叶片和冠层光谱反射特性与光合行为特征之间的关系。在滋贺吉柳实验流域和兵库县阿古实验场进行了田间试验。利用涡动相关方法对吉柳站的多季CO_2/H_2O通量进行了观测。在此基础上，建立了一个描述林冠与大气CO_2/H_2O交换的大叶型数值模式，该模式能合理地估计热量、水汽和CO_2通量的季节变化，并能计算林分的年同化率。在Akoh站点进行通量观测，重点是冠层结构的影响。该模式能较好地预报辐射、风速、热量、CO_2和H_2O通量的垂直分布。利用高分辨率多光谱仪和便携式光合仪对盆栽万年青树进行了室内试验。结果表明，由叶片光谱反射率反演的NDVI并不总是与光合行为相对应，这表明需要利用远红外反射率作为地表温度指标来遥感光合作用的实时响应，即使是单个叶片尺度。

In order to establish the methodology for assessing ecophysiological conditions of vegetation using remote sensing technique, field and laboratory experiments were conducted to clarify the relationship between characteristics of photosynthetic behavior and properties of spectral reflectance in leaf and canopy scale. The field experiments were conducted at the Kiryu Experimental watershed in Shiga prefecture and the Akoh experimental site in Hyogo prefecture. Multi-seasonal CO_2/H_2O flux observations were carried out using eddy correlation method with various micro meteorological measurements in the Kiryu sites. Based on the experimental results in this observation, a big leaf type numerical model describing the CO_2/H_2O exchanges between canopy and atmosphere was developed, The model could reasonably estimate the seasonal variations of heat, vapor and CO_2 fluxes, and could calculate the annual assimilation rate of forest stands. The flux observations in the Akoh site were conducted focusing on the influences of canopy structure. The model developed for this experiments can predict the vertical distributions of radiation, wind speed, heat, CO_2 and H_2O fluxes. The laboratory experiments were operated on several broad-leaf evergreen trees planted in pots using a high-resolution multi-spectral meter and a portable photosynthesis meter. The results shows that the NDVI derived from spectral reflectance of leaves did not always correspond to photosynthetic behaviors, This suggests that utilization of the far infrared reflectance as a surface temperature index is required to sense remotely the real-time responses of photosynthesis even for individual leaf scale.