关键词: 黄土高原, 半干旱区, 苹果园地, 密度, 水分生产力, WinEPIC模型

Abstract: Weeds are one of the most important factors affecting agricultural production and have been controlled. People have paied more and more attention to the ecosystem functions of weeds recently. This paper gives a simple description on recent studies of the ecosystem functions and the conserving approaches of weeds in agroecosystem. It is suggested that it is necessary to understand the positive and negative impacts of the weeds on agricultural production and ecosystem functions. This would help determine how agriculture objectives and practices could be modified to enhance the conservation of the weeds and other biological resource for the long-term viability of agriculture.

Key words: Loess Plateau, semi-arid region, apple orchard, planting density, water productivity, WinEPIC model.