Classification of the structure of forest canopy from the viewpoint of redistribution of solar radiation and storm water

森林冠层具有多层次的特征。森林冠层与草地冠层在吸收太阳辐射、截流雨水和蒸发蒸腾方面存在较大差异。研究的重点是太阳辐射的吸收。观测装置安装在日本大学湘南校区针叶林和泰国热带季节森林。研究结果总结如下。1)研究了针叶树与阔叶树对太阳辐射透过率的差异。在散射辐射情况下，无论是针叶树还是阔叶树，太阳辐射都随冠层开度的增加而减小。在直接辐射条件下，50%和15%的辐射分别通过同样开度为50%的针叶和阔叶冠层。针叶树的冠层结构使更多的太阳辐射能够被透射到冠层。2)研究了树木落叶休眠期冠层变化对到达地面的辐射的影响。在休眠期，太阳辐射均匀地穿透森林冠层。在针叶林和阔叶林之间，太阳辐射的空间变化较小。3)在泰国澄迈郊区对热带季节森林进行了观测。植被是有落叶期的常绿森林。研究了以冠层导度和生化光合作用模型为子模型的大叶模型参数。在一年内进行4次特殊（人工）测量的数据中，Gmax（最大冠层导度）、p（叶绿素密度）和e(1-f)（可用于PCR/PCO循环的事件PAR的分数）在休眠季节值较小。在雨季，它们的价值很高。此外，还研究了这些参数是否有季节变化。少

The characteristics of forest canopies is multi-layers. The large difference exists between a forest canopy and a grass canopy in absorption of solar radiation, interoeption of storm water and evap-transpiration. The research is carried out putting the stress on the absorption of solar radiation. The observing apparatus are installed in the forest in the conifer forests in Shonan campus of Nihon University and tropical season forests in Thailand. The results of the research is summarised as follows.1) The difference of transmittance of solar radiation between conifer trees and broad leaved trees is investigated. In case of the scattered radiation, the solar radiation decreases with the area of openness of canopies in both conifers and broad leaved trees. In case of the direct radiation, 50% and 15% of radiation transmitted the canopy of conifers and broad leaved with the same openness of 50%, respectively. The conifer has the canopy structure making more solar radiation transmittable i … More nto the canopy.2) The influence of the change of canopy to the radiation arriving at the ground in dormant season when tree, leaves fall is investigated. In the dormant season, solar radiation penetrates forest canopies uniformly. Spatial variations of solar radiation is small in forests between conifers and broad leaved trees.3) The observation of tropical season forests was carried out in the surburb of Chengmai, Thailand. Vegetation is evergreen forests which has the period of the fall of tree leaves. The parameters of Big Leaf Model which indudes canopy conductance and bio-chemical photosynthesis model as sub-model are investigated. With the data of special (manual) measurements conducted four times in a year Gmax (maximum canopy conductance), p(density of chlorophyl1), and e(1-f)(fraction of the incident PAR available for PCR/PCO cycles) showed small values in dormant season. In wet season, they were high values. In additions, it is investigated whether these parameters have seasonal variations or not. Less