樹木の成長,樹種の違いが樹冠の葉面積密度・光学的深さに及ぼす影響 : 実測に基づく街路樹の日射遮蔽効果の評価手法に関する研究  [in Japanese] EFFECTS OF GROWTH AND TYPES OF TREES ON LEAF AREA DENSITY AND OPTICAL DEPTH ON TREE CANOPY : Study on method to evaluate the shading effect of street tree on solar radiation based on field observation  [in Japanese]

Planting of trees is the most useful technique to ease the outdoor thermal environment in summer. This paper describes a method to evaluate the shading effect of street tree on solar radiation based on field observation. In former part of this paper, the method to estimate parameters for evaluating the shading effect of tree crown on solar radiation is described. Using data from field observations of the amount of global solar radiation, solar radiant transmittance of tree crown, and sky view factor, we estimate leaf area density, optical length, and 'ak', that is the product of leaf area density and extinction coefficient, in this study. In the latter part of this paper, the authors evaluate the 'ak' of street trees in Fukui city, and examine the disposition of leaves in tree crown by the data from field observations of azimuth of leaves, inclination of leaves, and tree height. By these examinations, it is clarified that 'ak' is affected by tree species and growth of street tree.