过去2000年中国农耕区拓展与垦殖率变化基本特征

通过梳理和集成近年研究成果,综述了过去2000年中国主要农耕区拓展的阶段性及其间全国耕地面积和其中近千年垦殖率变化的主要特征。主要结论有：① 中国主要农耕区第一次大规模拓展出现在西汉,从黄河中下游拓至整个长江以北地区;第二次在唐宋时期,主要是长江以南农耕区域从平原低地拓垦至丘陵山地;第三次在清中叶以后,主要是对东北、西北和西南等边疆地区的拓垦和山地的深度开发。② 过去2000年中国耕地面积呈波动增加趋势,公元初突破5亿亩（1亩≈ 667 m²）,8世纪前期突破6亿亩,11世纪后半叶达近8亿亩,16世纪后期突破10亿亩,19世纪前期突破12亿亩,1953年逾16亿亩,1980年逾20亿亩。③ 中国耕地空间分布的主体格局至11世纪前后就已基本奠定。1080年前后,黄淮海、关中平原等的垦殖率达30%以上,长江三角洲、鄱阳湖平原、两湖平原和四川盆地等达30%左右。1850年前后,华北平原、汾渭盆地和陇东地区、四川盆地、两湖平原、鄱阳湖平原及长三角地区等的垦殖率均超过30%。2000年前后,东北平原、黄淮海地区、汾渭盆地和陇东地区、四川盆地、长江中下游平原等农业区中有2/3以上垦殖率超过50%,辽西丘陵、坝上高原、黄土高原及南方各省的丘陵山地也多达15%以上;西北绿洲农业带及青藏高原河谷农业带的局部地区也达50%以上。

General characteristics of the agricultural area and fractional cropland cover changes in China for the past 2000 years

By synthesizing the results from recent peer-reviewed publications on the agricultural history and the historical cropland cover reconstruction in China, we summarized the general characteristics of the agricultural area and fractional cropland cover changes in China for the past 2000 years. The conclusions are drawn as follows: (1) In the western Han Dynasty, the main agricultural areas expanded from the middle and lower reaches of the Yellow River to the northern China. During the Tang and Song dynasties, the expansion of the agricultural areas that mainly occurred in southern China featured from the plain to hill and to high-land. From the middle of Qing Dynasty, the expansion of the agricultural areas mainly occurred in the border areas including Northeast China, Southwest China, and Northwest China, as well as remote regions mountains. (2) In the past 2000 years, the total cropland area in China has been increased in general although there were fluctuations. The cropland area reached about 500, 600 and 800 million mu around beginning of the 1st century, the early 8th century and the late 11th century, respectively. It exceeded 1, 1.2, 1.6 and 2 billion mu around the late 16th century, the early 19th century, 1953 AD and 1980 AD, respectively. (3) In China, the pattern of cropland was formed in the 11th century. Around 1080 AD, the cropland cover fraction accounted for more than 30% in the Huang-Huai-Hai Plain and the Guanzhong Plain and about 30% in the Yangtze River Delta, the Jianghan-Dongting Plain, the Poyang Lake Basin and the Sichuan Basin. Around 1850 AD, the cropland cover fraction took up more than 30% in the North China Plain, the Weihe and Fenhe river basins and some parts of eastern Gansu Province, the Sichuan Basin, the Jianghan-Dongting Plain, the Poyang Lake Basin and the Yangtze River Delta. Around 2000 AD, in the agricultural areas including the Northeast China Plain, the North China Plain, the Weihe and Fenhe river basins and some parts of eastern Gansu, the Sichuan Basin and the middle and lower reaches of the Yangtze River, more than two-thirds of which had a cropland cover fraction of more than 50%. The cropland cover fraction was more than 15% in the Western Liaoning hills, the Bashang Plateau, the Loess Plateau, as well as the hilly and mountainous areas of southern China. The highest cropland cover fraction also exceeded 50% in some oasis agricultural areas and the valley agricultural areas on the Qinghai-Tibet Plateau.