关于日本扁柏人工林光能利用效率的研究(Ⅰ)——群落生产结构与现存量、生长量和光能利用效率

In this investigation we have determined that the standing crop of aChamaecyparis obtusa plantation of 21 years was 160 t/ha, the increment,16.5t/ha·a; and the net solar energy utilization ratio 0.64% by combiningthe correlative growth method with the stratified crop method. This ratiowas not high in the Fu Ku Ka district, Japan. From the relationship bet-ween the weight of dry matter and D2·H correlative growth, the verticaldistributions of dry matter in different storeys were calculated. The sea-sonal changes of solar radiation energy in the top canopy and the differentstoreys inside were investigated with a sun-station system reader model700, which also gives the graph of the productive structure. From ourresults of investigation on the locations of the leaves in different partsin canopy, we suggested that the crowns with full closed canopy in a Cha-maecyparis obtusa plantation can be divided into cone and cylinder crownsas the crowns in a Cryptomeria japonica plantation. Their leaf area indicesand leaf densities were 35±5cm2/g, 495g·/m3; 45±5cm2/g·and 222g/m3respectively. The effects of the productive structure in a stand on solarenergy utilization were also discussed, according to volume analysis, com-munity productive structure as well as the distribution of solar energy.