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 tw o subsystems and emergy production of the fish subsystem are growing. Emerg y 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 w ill gradually decline, but that of the compound ecosystem will firstly incr ease and then decrease. Net emergy allocation per human capita in the compo und ecosystem will slowly inecrease, but it will decrease if the animal sub system is removed from the ecosystem; this shows that the animal subsystem is a necessary part of the compound ecosystem. Relative to buffering capaci ty, emergy efficiency of the compound ecosystem, and recent living quality of local people, sustainable development of the ecosystem is discussed. (C) 1998 Elsevier Science B.V. All rights reserved.