The southern region is rich in heat and precipitation and has good agricultural production conditions. China is the largest producer of rice, pigs, citrus, tea, sericulture, sugar cane, aquatic products and tropical crops. As shown in Figure 4, Hainan Island, southern Taiwan Province Island, Leizhou Peninsula and Xishuangbanna, Yunnan Province are the main production bases of tropical crops in China, while wheat is mainly distributed in northern China.