Study On Ecological Security Evaluation Of Cultivated Land In Jiangjin District Of Chongqing

Cultivated land is the material basis for human survival and development,and the essence of land resources,which plays an essential role in the protection of national and regional economic development and social stability.Cultivated land utilization system is an important part of ecological environment system.As an important aspect of ecological security research,the cultivated land ecological security evaluation has important significance in understanding land ecological security problems scientifically and promoting the ecological civilization construction.China has a large population but limited arable land and the contradiction between people and farmland is intense.With the rapid development of industrialization and urbanization,the phenomenon of unreasonable land use occurred frequently and the quantity and quality of cultivated land both showed a downward trend.For example,the excessive input of pesticides and fertilizers,plastic lm and other agro-products in agricultural production had seriously polluted soil of cultivated land.And the continuing deteriorated land use ecosystem services posed serious threat to the coordinated development of the sustainable utilization between cultivated land and humans.Taking the cultivated land in Jiangjin District of Chongqing as study case,this paper had analyzed its current situation of cultivated land use and ecological environment.Based on "PSR"(pressure state response)conceptual model,23 evaluation indexes were selected to construct the evaluation index system of cultivated land ecological security.The comprehensive evaluation of cultivated land ecological security level in Jiangjin area was carried out by combining subjective and objective weighting method and multi factor comprehensive evaluation model.Through the data of comprehensive evaluation scores,this paper also analyzed the change characteristic of cultivated land ecological security time series in Jiangjin District from 2006 to 2015.Select 2009,2012,and 2015 as the time section,the spatial difference of cultivated land ecological security in Jiangjin area was analyzed.The ecological security problems of cultivated land utilization in Jiangjin were identified by combining the current situation of cultivated land use with social economic development.Finally,this paper put forward some countermeasures about improving the ecological environment and the ecological service function of cultivated land in Jiangjin District to provide a reference for the sustainable development of land and the maintenance of ecological security of cultivated land.The main findings of this study are as follows:(1)The ecological security status of cultivated land in Jiangjin district is still need to be improved.During the period of 2006-2015,the comprehensive value of cultivated land ecological security has experienced "falling fast-rising slow-dropping" three stages: The first stage is 2006 – 2009,the ecological security of cultivated land was deteriorating.And the safety level decreased from critical level in 2006 to sensitive level in 2009;The second stage is 2009-2012,the ecological security situation of cultivated land in Jiangjin district was developed rapidly,and the safety level increased rapidly from the sensitive level in 2009 to the comparative safety level in 2012;The third stage is 2012-2015,the ecological security situation of cultivated land in Jiangjin district was gradually deteriorated,from the comparative safety level in 2012 to the critical safety level in 2015.(2)The general situation of cultivated land ecological security of each township was roughly in line with the global Jiangjin district,but there are still obvious spatial differences between different towns.In 2009,the general situation of cultivated land ecological security was not optimistic.In 26 towns,Degan,Bolin,Youxi,Jiasi and Shuangfu belonged to the sensitive security level;Zhuyang,Wutan,Shimen and other 13 towns belonged to the critical safety level;Tanghe,Baisha,Ciyun,Longhua and Yongxing belonged to the comparative safety level;And only 2 towns had a comprehensive index of cultivated land ecological security greater than 0.58.By 2012,the ecological security of cultivated land in all towns was improved,Bolin,Youxi,Jiasi and Shuangfu four towns,which belonged to the sensitive security level in 2009 has been transformed into a critical safety level;Shuanghe,Baisha,Yongxing three towns belonging to the critical security level in 2009 had risen to a relatively safe level;Ciyun and Longhua belonging to comparative safety level in 2009 achieve security level.The amount of towns whose cultivated land ecological security index greater than 0.58 reached 14;However,the comprehensive index of towns all had different degrees of decline: Longhua town dropped to comparative safety grade,while Caijia,Wutan,Dushi,Jiaping,Luohuang,Shima,Lishi,Baisha,Shimen and Yongxing 10 towns has been reduced to safety critical safety;Shuangfu Street also dropped to the sensitive level from the critical safety;And only 4 towns had land ecological security comprehensive indices more than 0.58.(3)Based on the comprehensive evaluation of cultivated land ecological security and the diagnosis of obstacle factors,we have found the following issues:(1)Environmental pressure was the primary factor restricting the ecological security of cultivated land in Jiangjin,and the four main obstacle factors were amount of plastic sheeting use,agricultural fertilizer load,feticide load and wastewater load of per unit cultivated land.(2)The social and economic pressure and the natural pressure were important factors that restrict the ecological security of cultivated land in Jiangjin District,which mainly involves three obstacles: The level of urbanization,the proportion of agricultural economy and the area of natural disaster.(3)The quality,land use status and response to environments three cultivated land ecological security barriers were also increasing year by year,which mainly relates to the content of soil organic matter and area of effective irrigation,area of farmland in nature reserves,land reclamation rate four factors.(4)As an important grain producing area in Chongqing,in the future,Jiangjin should actively promote green agriculture,strengthen the agricultural infrastructure construction and protection,and promote the establishment of ecological safety supervision system of cultivated land,cultivated land ecological security supervision and early warning system,and implement mechanism of cultivated land protection.In addition,Jiangjin district should dig deep the reserved cultivated land resources,promote the ecological restoration project,and implement the ecological compensation mechanism of cultivated land.