A study on the comprehensive assessment of agro—ecosystem in the Three Gorges Reservoir Area

According to the principles in setting up index system of eco-agriculturalland evaluation．a reference index cor-pus which can be selected by diferent eco-agricultural regions is established．The principal component analysis(PCA)is used to select and optimize indexes from nineteen ones in four index groups．Finally，eleven indexes are defined as the index system of land evaluation for the eco-agricultural county、