Abstract: 【Objective】 Under the background of climate change, the changes of cropping boundary and its effect on yield in South China were studied. 【Method】 Based on the historical weather data of 281 stations in 15 provinces (cities, autonomous regions) in south China, the trends of ≥0℃ accumulated temperature and annual precipitations were analyzed briefly. The changes of grade 0 areas under climate change were studied according to the thermal indicators of heat. Furthermore, the changes of grade 1 areas were analyzed combining with the precipitation indicators. The changes of yield were studied based on the data of yield during 2000-2007. 【Result】 The trends of ≥0℃ accumulated temperature increased and the mean annual value was 60.05 ℃•d/10a; The trends of ≥10℃ accumulated temperature increased. The mean annual trends value of annual precipitations was 1.93 mm/10a, and the spatial differences were large. Compared with the situation before 1980, there was no significant change in the boundary of one-crop per year in South China; however, the change of boundary between two-crops and three-crops per year was marked, which moved with about 2′ to west and 20′ to north. The area of three-crops per year was enlarging, while the areas of two-crops and one-crop per year were reducing. The change of grade 1 area from 1980 was also significant. The south boundary area of two-crops in irrigated land and two/one-crop in dry land in Huanghuaihai area (part of South China) moved to north. Area of wheat-rice in Jianghuai plain or hill moved to north and enlarged. The north boundary of area of two/three-crops in paddy/dry land in Sichuan basin moved to south in the northeast part of Sichuan Province. The west and southeast boundary of area of two-crops in paddy field and two/one-crop in dry land in Southwest plateau or mountain moved to west, while there was no significant change on the area. The north boundary of area of two/three-crops in paddy field in middle-lower Yangtze plain or hill moved to north as well as the west boundary moved to west, and the area enlarged. The north boundary of area of later two/three-crops and thermal three-crops in South China moved to north and the area enlarged. The changes of cropping systems were benefit for increasing the yield in the most areas. 【Conclusion】The effect of climate change on the cropping system was so great that the boundary of multiple cropping moved to north and west, and the area enlarged. That was benefit for increasing the yield generally.

Key words: climatic change, South China, the northern limits of cropping system, crop yield