Evaluation On Cultivated Land Ecological Security Based On Set Pair Analysis

Cultivated land is an important natural resource and the basic means of agricultural production.However,on the one hand,people pursue higher economic benefits,converting cultivated land into construction land,which leads to the reduction of cultivated land.On the other hand,natural disasters such as excessive use of pesticides and soil erosion have reduced the quality of cultivated land.Therefore,it is of great significance to study the ecological security of cultivated land for understanding the ecological situation of cultivated land and putting forward the measures for protecting cultivated land.In China,the research on cultivated land ecological security mostly chooses the same level data as the basic data to draw a direct conclusion.This paper takes the county as the unit to study the provincial cultivated land ecological security and ensure the data basis.There are many factors affecting the ecological security of cultivated land,and there is a complex and uncertain relationship between the evaluation indicators.Set pair analysis is a method to deal with multi-index problems,but it is seldom used in the field of cultivated land ecological security research.In this paper,the set pair analysis method is used to evaluate the ecological security of cultivated land,and the spatial and temporal analysis of the ecological level of cultivated land in 86 counties of Gansu Province from 2011 to 2016 is carried out.The level and trend of cultivated land ecological security in Gansu Province in the past six years are studied and the main influencing factors are analyzed.The results show that:(1)The ecological security of cultivated land in Gansu Province increased from 2011 to 2016.It can be divided into two stages,i.e.the relatively unsafe level(IV)in 2011 and the critical safety level(III)in 2011-2016.From the point of view of the criterion level,the pressure system of cultivated land ecological security is in a relatively safe level(II),the unsafe level(V)in the system of cultivated land ecological security status,and the response system of cultivated land ecological security is on the rise trend of fluctuation and develops to a relatively safe level(II).(2)In 2016,the ecological security grades of cultivated land in the counties(urban areas)of Gansu Province were quite different,and all five grades were distributed,but most of them were concentrated in the three grades of safer(II),critical(III)and less safe(IV).21,32 and 22 counties(urban areas)of each grade accounted for 20.69%,38.39% and 30.69% of the total cultivated land area of Gansu Province,respectively.There are 8 counties and 3 counties with safety grade(I)and unsafe grade(V)respectively,which account for 6.28% and 3.95% of the total cultivated land area in the province.(3)The ecological security level of cultivated land in Gansu Province from 2011 to 2016 shows a trend of high in Northwest and low in southeast.The ecological security of cultivated land in Hexi area is better than that in other areas.In the past six years,39 counties have improved the level of cultivated land security,7 counties have declined the level,and 40 counties have not changed the level.(4)According to the diagnostic results of obstacle factors,the main obstacle factors restricting the ecological security of cultivated land in Gansu Province are disaster index,fertilizer load per unit cultivated land,grain yield per unit area of cultivated land and effective irrigation area ratio in 2011,and disaster index,fertilizer load per unit cultivated land,grain yield per unit area of cultivated land and net income per capita of farmers in 2016.Therefore,we should strictly control the amount of chemical fertilizer and pesticide application,raise people’s awareness of arable land protection,increase land input,improve the output capacity of arable land,and ensure the quantity of arable land.