Considering the main factors ofecological environment affecting citrus yield, based on the data from past three years observation of Wenzhou Citrus orchard in Kaihua village as a low hill-red soil ecological environment in the middle of the subtropical monson region, the statistical method was used to simulate the citrus harvest. The main factors of ecological environment associated with citrus yields in several key periods were as follow: cold injury leading to leaves drop in early or middle winter, anomal...