Why the more trophic levels, the higher the energy utilization rate;
First, in the ecosystem, the starting point of energy flow is the fixed solar energy of producers through photosynthesis. The total energy flowing into the ecosystem is the total solar energy fixed by the producers through photosynthesis. The trend of energy generally has four aspects: first, respiratory consumption; Second, it is used for growth, development and reproduction, that is, it is stored in the organic matter that constitutes the organism; Third, the remains, wreckage and excrement of the deceased. Decomposed by decomposers; The fourth is the organism that flows into the next trophic level. The more trophic levels, the stronger the respiratory function of energy; The more trophic levels, the greater the storage of biological organic matter; The more trophic levels, the more substances are provided for decomposers; The more trophic levels, the higher the energy delivered for the next trophic level. In the ecosystem, energy flow and carbon cycle are closely linked. Carbon is the last reserve of trophic level.
Second, the energy flow is characterized by one-way flow and gradual decline. One-way flow means that the energy flow of the ecosystem can only flow from the first trophic level to the second trophic level, and then to the subsequent trophic levels in turn. Generally, you can't go upstream. This is determined by the predatory relationship between animals. For example, wolves prey on sheep, but sheep can't prey on wolves. Gradual change means that the energy input to one trophic level cannot flow into the next trophic level, and the energy decreases step by step in the process of flowing along the food chain. The average efficiency of energy transmission along the food chain is 10% ~ 20%, that is, only 10% ~ 20% of energy in one trophic level is used by the next trophic level.
Third, the energy flow in the ecosystem is unidirectional, and the energy passing through each trophic level gradually decreases.