Spatiotemporal Changes And The Sources Security Evaluation Of Sloping Farmland Areas

Sloping farmland is an essential type of the farmland resource in China.Sloping farmland of southwest region accounted 90%.Slope cropland is an ecosystem involving the interaction of both natural and social factors.There have been some studies on the influence of natural factors on sloping farmland,but the study of human factors on sloping farmland is still insufficient.In this study,we focused on spatiotemporal change of the sloping farmland and its influence factors,security evaluation and suggestions for sustainable development of sloping farmland in Sichuan.Data of sloping farmland were extracted from geographic data from digital elevation model(DEM),administrative map and land use maps in 2000,2005,2010 and 2015,evaluation indexes were acquired from statistical information and references.We used a principal component analysis(PCA),correlation analysis and meta-analysis in this paper.The main results of this study are as follows:(1)The spatiotemporal changes of the sloping farmland and its influence factors were studied.From2000 to 2015,Sloping farmland area has decreased to 3263 km~2,and the reduction rate of gentle slope cultivated land was faster than that of moderately steep sloped land,while the reduction degree of slope cultivated land in developed areas was greater than that in underdeveloped areas.Meanwhile,the farmland area with a>25°slope,which is not suitable for farming,has decreased significantly,especially in the western region and in the three major minority autonomous prefectures.Social factors and economic factors had a significant negative correlation with the area of sloping farmland in the Sichuan Province,while the load coefficient of agricultural intensity factors was relatively small.From the comprehensive inference of the driving forces,the strongest factors with effects on sloping farmland were economic factors,followed by social factors,and then agricultural development factors were the weakest.(2)The security status of slope cultivated land resources were revealed in Sichuan.A evaluation system with 20 indexes was established based on DPSIR model,which come to society,economy,characteristics of sloping farmland,management and soil nutrient.The study showed that high security region distributed in the several surrounding cities of the capital of Sichuan province,with a upper level of economy and society.Moderate safety regions included 3 cities(states)with abundant tourism resources and enough attention to ecological development.Low safety regions included the eastern rim of Sichuan and Mianyang.The critical safety regions included 2 big cities in population and Guangyuan.The economic and urbanization process of Chengdu plain developed rapidly,but the protection of sloping farmland in this area has not been paid enough attention.Disturbed city,included Liangshan,Yi Autonomous Prefecture and Ganzi Tibetan Autonomous,located in the poorest areas of Sichuan,which cannot provide financial support for the protection of the sloping farmland.(3)The suggestions for sustainable development of the sloping farmland in Sichuan were presented.Based on the state of sloping farmland in Sichuan,we choose 23 filtered references which related to sloping farmland utilization in Sichuan region,the main challenge of sustainable utilization of sloping farmland is to improve soil fertility and control soil erosion.Protective measures for slope cultivated land(2-15°)were increasing soil fertility supplemented by soil and water conservation measures,farming measures(such as ridge soil,transverse slope ridge and no-tillage)and biological measures(such as hedgerow)were used widely.The farmland area with a>25°slope,which is not suitable for farming,should continue to complete the ecological conversion.The farmland area with a15-25°slope is the main object of disaster prevention and control of slope cropland,which with a relatively weak productivity and serious soil erosion.Engineering measures(such as slope water works and slope-to-terrace)used often in this region,with a purpose of changing the confluence channel and confluence condition of sloping farmland,reducing the negative impact of surface runoff and soil erosion,and achieving the sustainable utilization of sloping farmland.In summary,sloping farmland areas decreased and the reduction rate of gentle slope cultivated land was faster than that of moderately steep sloped land with the development of society and economy.To ensure the sustainable use of sloping farmland,population growth and town covers should be controlled and planned.