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生态系统的功能主要表现在生物生产、能量流动、物质循环和信息传递等方面。它们是通过生态系统的核心——即生物群落来实现的。太阳光能通过绿色植物的光合作用转变为第一性生产量,即生物生产,成为进入生态系统中可利用的基本能源,使得生态系统中各级生物的生命活动得以正常进行。基本能源在生态系统中能量的消耗、转移、分配过程是通过各级生物成分间以食物的形式表现的。能量从输入逐级流通直到输出,其能流为单程流,数量为逐级锐减,能流越流越细,直到最后以废热形式全部散失为止。由于来自太阳辐射的能量,经过生态系统的暂时固定、流动,仍然返回空间。因此,生态系统是一个能量开放系统,要维持生态系统功能的正常进行,就得不断地向系统输入能量。
Ecosystem functions are mainly manifested in the aspects of biological production, energy flow, material circulation and information transmission. They are achieved through the core of the ecosystem - the biome. Through the photosynthesis of green plants, sunlight can be transformed into primary production, that is, biological production, becoming the basic energy source available to the ecosystem, enabling the life activities of all levels of organisms in the ecosystem to proceed normally. The energy consumption, transfer and distribution of the basic energy in the ecosystem are expressed in the form of food through the biological components at all levels. The energy flow from input to output step by step until the output, the energy flow for the one-way flow, the number of step-by-step decrease, the energy flow through the thinner until the final form of waste heat all dissipated so far. As the energy from the solar radiation, through the temporary fixation of the ecosystem, flows, it still returns to space. Therefore, the ecosystem is an open system of energy. To maintain the normal functioning of the ecosystem, energy must be constantly input into the system.