Energy flow of agro-fruit ecosystem in the Loess Plateau of Shaanxi Province

We examined energy flow in the agro-fruit ecosystem in the south central part of the Loess Plateau of Shaanxi Province, at Feimahe and Nangou Villages of Baota District of Yan’an Municipality, and Xipo Village of Chunhua County. The results show that energy output-input ratio of the agro-subsystem is 3.58 compared to 1.86 for the fruit-subsystem; 3.17 for livestock-subsystem, 0.41 for humansubsystem and 1.17 for the whole ecosystem. Among the subsystems, net energy use is highest (1.281×10¹³ J per village per year) in the humansubsystem. Energy output of economic products (food grain and fodder) in the agro-subsystem is 3.47×10¹² J per year. Of this energy, 97% is used within the ecosystem and only 3% is marketed out. Fruit energy output for the fruit-subsystem is 4.14×10¹² J per year, of which 45% is used in the ecosystem and 55% marketed out. Annual energy output of the livestock-subsystem is 5.38×10¹² J, which constitutes 14% of total energy output in the ecosystem. In summary therefore, the energy analysis shows that the agro-fruit ecosystem is a developing agricultural ecosystem that includes food production for local consumption, and a market-oriented fruit industry linked with livestock-subsystem and supported by market forces. The industrial structures of the ecosystem need adjustment for higher productivity and better sustainability by stabilizing agricultural production, developing livestock industry and intensifying fruit production.