ased on the 1975-1990 data on energy flow through an agricuitural ecosystem inPuwa ,located in the southwest mountain area of Beijing city ,where the studies on the struc-ture and functions of ecosystem have been carried out ,the stability and dynamics of theenergy flow through this ecosystem were further analyzed. By establishing a compartmentmodel for energy flow and making a mathematically dynamic simulation based on the model,it was found that the ecosystem is presently in a state of deviating from its...