Studies of emergy flow in a compound agro-ecosystem in the Taihu Lake area, Jiangsu Province, China

Emergy flow in a compound agro-ecosystem in the Taihu Lake area of Jiangsu province, China, is studied with a set of numeric models. Model parameters are based on 11 years of records. Results show that total emergy production of two producing subsystems will decline although emergy input into the two subsystems and emergy production of the fish subsystem are growing. Emergy efficiency of the producing subsystems, both gross and net, will decrease, while emergy efficiency of the compound ecosystem will grow up first and then gradually decline. Net emergy production of the producing subsystems will gradually decline, but that of the compound ecosystem will firstly increase and then decrease. Net emergy allocation per human capita in the compound ecosystem will slowly increase, but it will decrease if the animal subsystem is removed from the ecosystem; this shows that the animal subsystem is a necessary part of the compound ecosystem. Relative to buffering capacity, emergy efficiency of the compound ecosystem, and recent living quality of local people, sustainable development of the ecosystem is discussed.