Tracking the spatio-temporal change of cropping intensity in China during 2000-2015

Improvement in the efficiency of farmland utilization and multiple cropping systems are of prime importance for achieving food security in China. Therefore, spatially-explicit analysis detecting trends of cropping intensity are important preconditions for sustainable agricultural development. However, knowledge about the spatiotemporal dynamics of cropping intensity in China remains limited. In this study, we generated annual cropping intensity maps in China during 2000-2015 using a rule-based algorithm and MODO9A1 time series imagery. We then analyzed the spatio-temporal changes of cropping intensity. The results showed single-cropping and double-cropping areas were about 1.28 +/- 0.027 X 10(6)km(2) and 0.52 +/- 0.027 X 10(6)km(2) in China in 2015 and their areas were relatively stable from 2000-2015. However, cropping intensity had substantial spatial changes during 2000-2015. About 0.164 +/- 0.026 x 10(6)km(2) of single-cropping area was converted to doublecropping area, which mainly occurred in the Huang-Huai-Hai Region. About 0.193 +/- 0.028 x 10(6)km(2) of double-cropping area was converted to single-cropping area, which mainly occurred in the southern part of China. About 85% of croplands with decreases in cropping intensity were located in the southern part of China, and about 80% of croplands with increases in cropping intensity was distributed in the Huang-Huai-Hai Region and the northern part of the Middle and Lower Reaches of the Yangtze River region (p < 0.05). The landscapes of different cropping systems tended to be homogenized in major agricultural production regions.