生态系统能量单向流动,不能循环,不能逆流是广为人知的,但实际上,生态系统能量流动并非绝对是单向的。在生态系统中,平常所见的食物链有三类:一、捕食链。它是通过相连两营养级的捕食关系形成的。如植物→鼠→蛇→鹰形成的一种食物关系。在捕食链中,能量流动绝大多数遵循从生产者流入消费者,从初级消费者流入次级、三级等消费者的单向流动的规律。但在捕食链中,也存在着少数特殊的现象(如猪笼草捕食小虫,蛇在冬季被鼠吃掉),致使生态系统中有少部分能量产生逆流现象。二、腐生链。它是由分解者(细菌、放线菌、真 Ecosystem energy is one-way flow, can not be recycled, and it is well known that it is impossible to reverse flow. However, in fact, the energy flow of ecosystem is not absolutely unidirectional. In the ecosystem, there are three types of food chains that are commonly seen: I. Prey chains. It is formed by the predation of two trophic levels. Such as plants → rats → snakes → eagles to form a food relationship. In the predator chain, the vast majority of energy flows follow the law of one-way flow from producer to consumer and from primary consumer to secondary and tertiary consumers. However, there are also a few special phenomena in the prey chain (such as nepenthes feeding insects, snakes eaten in winter), resulting in a small part of the energy in the ecosystem to produce countercurrent. Second, saprophytic chain. It is composed of decomposers (bacteria, actinomycetes, true