葉面積指数・光合成有効放射の鉛直プロファイル計測による熱帯雨林の光環境解析

抄録

As some of ecological functions, plant physiological activities are known. Most of sunshine is receiving at forest canopy layer which consist of leaves and branches. The leaves are using it as energy source for forest activities such as photosynthesis. When we consider the plant physiological activities, light environment is the most important. That is why we investigated forest light environment through vertical light environment measurements such as Leaf Area Index (LAI) and Photosynthetic Active Radiation (PAR ; 400-700nm) . The light distribution in forest is defined by vertical radiation distribution. The leaf component of canopy is quantified by its structural LAI. The LAI is how many leaves area is projected and accumulated on the unit of ground area. This important parameter regulates a number of ecological processes. Tree leaves normally absorb PAR and vertical radiation distribution is accumulations of radiation, absorption, defuse transmission and interception. This phenomenon is generally defined by the Lambert-Beer low. In order to know the vertical forest light distribution, LAI and PAR measurements were executed in Tropical Rainforest. Trough our LAI and PAR measurements results show the same tendency as high dense forest LAI. The LAI value is increasing from tree top to the bottom. It is the theoretical knowledge of nature that leaves area accumulates from top to the bottom. According to this result, LAI is recognized to be correlative relationship with canopy height.