Sustainability Analysis of Cropland Use in Cropping-Pastoral Ecotone before and after the Grain-for-Green Policy:A Case Study from Yanchi County in Ningxia

[Objective] This study aimed to analyze the sustainability of cropland use in cropping-pastoral ecotone before and after the Grain-for-Green Policy. [Method] Using Yanchi County in Ningxia Hui Autonomous Region as a case study area, this investigation used the annual transfer rate of land use types, cropland suitability and emergy analysis to examine the major pressures affecting the sustainable use of cropland before and after the Grain-for-Green Policy. [Result] The expansion of con- struction land onto cropland was significant; the annual cropland area was still larger than the land area suitable for cropping after the policy; agrochemical inputs used for crop production gradually increased and unit crop outputs required more agro- chemical inputs. Cropland use sustainability showed a fluctuating downward trend. [Conclusion] The results imply that the protection of high quality cropland, further im- plementation of the policy and control of agrochemical inputs according to precipita- tion are the main measures needed for sustainable cropland use in cropping-pastoral ecotone.

Spatio-temporal differences and factors influencing intensive cropland use in the Huang-Huai-Hai Plain

This study developed a comprehensive system to evaluate the intensity of cropland use and evolution of cropland use in the Huang-Huai-Hai Plain.Delphi-entropy methods were adopted to determine the weight of the index,and the Geo Detector model was established to explore the influencing factors.The results are summarized as follows:(1) The intensity of inputs,degree of utilization,and production increased continuously,but the intensity of continuous conditions experienced an overall decline followed by a rebound towards the end of the study period.The number of counties with high and moderately high intensity increased by 56.8% and 14.6%,respectively,from 1996 to 2011.The number of counties with moderately low and low intensity declined by 35.9 % and 11.9 %,respectively.Areas with significant increases in intensity were mainly distributed in northeast Hebei Province,northwest Shandong Province,and north Jiangsu Province.The intensity is high in northern Jiangsu and Anhui;the output effect remained above moderate intensity mainly near Beijing,Tianjin,Tangshan,and counties in the suburbs of Shijiazhuang.(2) Natural disasters,elevation,slope,and road networks were the main factors influencing the intensity of cropland use in this region,with influence values of 0.158,0.143,0.129,and 0.054,respectively.Areas with moderately high and high levels of intensity were distributed in low-lying areas.Uneven distribution of precipitation,seasonal drought,and flood disasters can directly affect the stability index of croplands and reduce the intensity of cropland use.Developed road networks are associated with moderately high intensity.Our results suggest recommendations such as promoting agricultural intensification and large-scale management,promoting the construction of road networks,improving early warning systems for drought and flood disasters,and promoting moderate and intensive use of arable land,and focusing on restoration and sustainable use of cropland.

Reconstruction of Lu-level cropland areas in the Northern Song Dynasty （AD976-1078）

Based on data on taxed-cropland area and on the number of households in historical documents, a probabilistic model of cropland distribution and a cropland area allocation model were designed and validated. Cropland areas for the years AD976, 997, 1066, and 1078 were estimated at the level of Lu（an administrative region of the Northern Song Dynasty）. The results indicated that（1） the cropland area of the whole study region for AD976, 997, 1066, and 1078 was about 468.27 million mu（a Chinese unit of area, with1 mu=666.7m2）, 495.53 million mu, 697.65 million mu, and 731.94 million mu, respectively. The fractional cropland area（FCA） increased from 10.7% to 16.8%, and the per capita cropland area decreased from 15.7 mu to 8.4 mu.（2） With regard to the cropland spatial pattern, the FCA of the southeast, north, and southwest regions of the Northern Song territory increased by 12.0%, 5.2%, and 1.2%, respectively. The FCA of some regions in the Yangtze River Plain increased to greater than 40%, and the FCA of the North China Plain increased to greater than 20%. However, the FCA of the southwest region（except for the Chengdu Plain） in the Northern Song territory was less than 6%.（3） There were 84.2% Lus whose absolute relative error was smaller than 20% in the mid Northern Song Dynasty. The validation results indicate that our models are reasonable and that the results of reconstruction are credible.