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

点击翻译按钮获取中文摘要

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