Research On The Ecological Security Evaluation Of Farmland In Semi-arid Areas Based On PSR Model ——An Example Of Hohhot

Farmland is the basic resource and condition of human survival.It’s security is not only the vital component to national and northern-border ecological security but also the indispensable basis for the food safety of China.Although the semi-arid area has larger proportion of the farmland,the quality is not satisfying.The ecological security of the farmland relates to the economical development and regional security.This paper takes Hohhot as an example to evaluate the ecological security of the farm land and analyze the obstacle factors.The purpose is to provide the reference to the three-dimensionals（quantitative qualitative and ecological）protection and sustainable development of the farmland.The data Based on the quality classification of farmland resources and the Third National Land Survey,this study takes farmland patches as the evaluation unit and carries out a study on the ecological safety of farmland,taking into account the natural geographical pattern and the actual situation of Hohhot.The results of the study as follow:1.This study used the "PSR" model to construct an evaluation system for the ecological safety of farmland.Select 3 criteria layers of pressure,condition and response and 10 factor layers named natural pressure,environmental pressure,social pressure,population pressure,quantity state,utilization state,environmental state,environmental response,economic response and social response,22 indicator layers to build an evaluation indicator system.2.Entropy method,comprehensive index method and Arc GIS spatial analysis method are used to evaluate farmland ecological security comprehensively.Over the past decade,the comprehensive index of the farmland ecology in Hohhot has increased from 0.442 to 0.486,and the farmland ecological security level has increased from critically safe to relatively safe.The pressure index shows an upward trend whereas state index is relatively stable.The response index shows a “first increasing and then decreasing” trend.3.Spatial auto correlation analysis was used to calculate the global Moran index and local Moran index for ecological safety of cropland respectively.According to the global Moran index calculation of the farmland ecological security,the Moran index is above 0,and there is a positive correlation between farmland ecological security in counties;Local Moran index of cultivated land ecological security show Tumed Left Banner and Tuoketuo county have a high-high aggregation trend while the Xincheng District,Yuquan District,Huimin District and Saihan district have a low-low aggregation trend.4.Diagnosis of the main barrier factors affecting the ecological security of farmland by means of a barrier degree model.the obstacle degree of criterion layer in Yuquan District,Huimin District,Xincheng District and Saihan district has always been pressure layer > state layer >response layer,and the obstacle degree of criterion layer in Tuoketuo County,Tumed Left Banner,Helinger County,Wuchuan County and Qingshuihe County has always been pressure layer > response layer >state layer.The barrier degree of pressure layer has always been the highest.Based on research through PSR models,composite index methods,spatial autocorrelation analysis and barrier degree models,etc.To enhance the ecological safety of farmland in the study area,the pressure layer should be weakened by increased the content of soil organic matter and reduced the area of arable land occupied by construction,strengthening the state layer by increased the area of farmland per capital,and strengthening the response layer by increased the level of agricultural mechanization and input to the primary industry.To increase the quantity and quality of the farmland and to promote the integration with ecological governance,population,economic growth,urban construction and the farmland reservation,can improve the risk resistance of the farmland ecosystem.