Evaluation Of Land Ecological Security In Typical Plateau Area Of Loess Plateau

The rapid development of science and technology has brought various benefits to human society,at the same time,it has also brought various ecological problems.The destruction of the natural environment by humans has intensified,especially with the acceleration of urbanization.The expansion and utilization of land has far surpassed the ecological carrying capacity of the land itself,and various ecological security problems caused by it have gradually been exposed.Land ecological security is the basic guarantee of ecosystem security,political and economic security,and human social security.It is also the precondition to ensure the healthy development of all other systems.Therefore,the study of land ecological security is of great significance.Based on the connotation of land ecological security,this paper selects Dongzhiyu,a typical surface area of the Loess Plateau,as an example.On the one hand,it pays attention to the safety of the land system itself,on the other hand,it pays attention to the safety of the land ecosystem to human production and life.To some extent,the influencing factors of its safety characteristics—geological environment level,soil comprehensive quality,NDVI,land ecosystem service value,based on GIS technology and related evaluation models,evaluate the land ecological environment from different perspectives.Concluded as follow:The comprehensive score of geological environment in the study area is 5,the geological environment is relatively stable,and it is suitable for various production and life-related activities.The areas with score 4,5 and 6 are the main contributing sources of the comprehensive index of geological environment,and the sum of the three areas accounts for 87.55% of the total area of the study area;the areas with higher score in spatial distribution are the central area of the plateau,which decreases step by step along the peripHery,and the overall score of the western region is lower than that of the eastern region;(2)Soil comprehensive quality index is 0.962,which belongs to a high level.Compared with the national soil nutrient classification standard,the contents of organic matter and nitrogen are extremely deficient.The average contents of copper,cadmium and lead in soil are 21.57 mg/kg,0.22 mg/kg and 18.06 mg/kg respectively,which are lower than the screening values of soil pollution risk of agricultural land;(3)The NDVI value of the study area in 2017 ranged from-0.189426 to 0.630395,with a mean value of 0.282618,and a concentrated distribution of 0.2-0.4,with medium and low vegetation coverage;(4)The total value of ecosystem services in the study area is 30.2346 million yuan per year.The value of ecosystem services per unit area is higher in the north and lower in the south.With Xifeng District and Xiaojin Town as the boundary,the value of ecosystem services in the north area is higher than that in the South area,and gradually decreases along the northwest to Southeast direction;(5)The comprehensive index of land ecological security in the study area is 0.3593,which is still at a safe level.The overall trend is low in the north and high in the south.The radiation increases to the peripHery with the urban construction land and the outcrop of ditches as the center;(6)Through principal component analysis,the spatial planning of ecological function dominant area of Pengyuan Township in the north,production function dominant area of Dongzhi Town in the South and life function dominant area of Xiaojin Town in the south is determined,and maintain the respective advantages of the region to form production,life and ecology.Coordinated development of space to improve the ecological safety level of human activities in the current study area.