森林生态系统生命活动需要的一切能量都来自太阳辐射能。其中大部分能量是以热量形式散失掉,只有一小部分能量为森林植物截取利用。用能量表示森林生产力是科学合理的方法,因相同体积或重量的木材,其蓄存的能量是不同的。杉木是我国亚热带普遍栽植的重要用材树种,在木材生产中一向占有突出的地位。但是长期生产实践表明,杉木连栽几代后,土壤肥力递减,病虫灾害严重,生产力大幅度下 All the energy needed for the life of a forest ecosystem comes from solar radiation. Most of the energy is dissipated as heat, and only a small fraction of the energy is used by forest plants. Using energy to represent forest productivity is a scientifically sound method, because of the same volume or weight of wood, its stored energy is different. Cunninghamia lanceolata is an important timber species widely planted in the subtropical region of China and has always occupied prominence in the production of timber. However, long-term production practices show that after successive generations of Chinese fir plantations, soil fertility diminishes, diseases and insect pests are severe, and productivity is drastically reduced