Agroforestry and grass combined ecosystem types and optimizedmodel design in Anjiagou river basin

Field investigation, analysis and evaluation of natural conditions, production situation and socioeconomic status in the Anjiagou river basin of Gansu province were conducted, through comprehensive analysis and evaluation of the structure, composition, function, inputoutput performance, formation background of typical agroforestry ecosystem models in basin, then selected the appropriate agroforestry ecosystem models to adapt to different site conditions. According to every models inputoutput performance costeffective and combining the main ecological function, five typical optimized combination of agroforestry models were selected as follows: model of water and soil conservation forest at steep sloping land, model of returning farmland to forest or grassland at gentle sloping land, model of agroforestry ecosystem at terraces land, model of rainwater collection around courtyard, model of water and soil conservation forest at gully erosion land. The optimized model in Anjiagou river basin would provide the way and reference for crops, trees, grass mixedtype and reasonable combination, selection of optimized compound model in arid and semiarid regions.