耕地景观生态安全评价方法及其应用

Method of cultivated land landscape ecological security evaluation and its application

耕地作为重要战略资源,其生态安全关系到区域稳定及社会可持续发展。该研究以秦皇岛东北部低山丘陵及东部沿海耕地景观为研究对象,以景观生态学及生态安全理论为依据,构建耕地景观生态安全评价模型,利用1990年、2000年和2010年3期TM(ETM+)遥感影像,对研究区耕地景观生态安全进行综合评价,并对生态安全格局、重心演变及其驱动力进行分析。结果表明:研究区耕地景观生态安全不断降低,耕地景观生态安全指数从1993年的0.63下降为2000年的0.50,低山丘陵区的耕地破碎化更为严重,其生态安全低于沿海区域;研究区域耕地景观生态安全格局变化明显,1993-2000年,Ⅰ级区基本无变化,ⅡⅢ级区相互转化,2000-2010年,Ⅰ级区和Ⅱ级区均出现了扩展,大部分由Ⅲ级区转化而来;近20 a来,耕地景观生态安全重心逐渐向秦皇岛市相邻区域靠近,沿海地区耕地景观生态安全明显增强。降雨量及径流量的减少、人口及经济增长以及土地利用政策是耕地景观生态安全格局变化主要驱动因素。

Ecological security is very important for regional development and society stability, and it has become a hot topic currently. The concept of ecological security can be understood from two aspects, namely the broader sense and the narrower sense. In a broader sense, ecological security includes natural, economic, and social ecological security, while in a narrow sense, it means the security of natural and half natural ecological system, including ecological system and environment security. As special public resources, the quantity and quality of cultivated land are closely related to national food security and social stability, and has great significance in the maintenance of national security. In this study, taking the cultivated land in eastern low hills and coastal region of Qinhuangdao, China as the research area, a cultivated land landscape ecological security evaluation model was built based on the principles of landscape ecology and ecological security. The model contained five landscape pattern indexes including fragmentation, isolation, fractal dimension and shape factor, which could reflect production efficiency, stability and resilience of cultivated land. With three TM（ETM＋） remote sensing images in 1990, 2000, and 2010 as well as GIS techniques, the landscape ecological security of cultivated land in the research area was comprehensively evaluated based on each town unit, and the evolution of landscape ecological security pattern and gravity center was analyzed using center of gravity method. At last, the driving factors of landscape ecological security evolution were discussed. The results showed that the landscape ecological security of cultivated land in the research area had been declining all the time with the value decreasing from 0.63 in 1993 to 0.5 in 2000. The fragmentation of cultivated land in low mountainous and hilly areas was more serious, so its landscape ecological security was lower than coastal area. The landscape ecological security was divided into three levels according to Natural Break grading result of three years includingⅠlevel when ecological security was equal or less than 0.3, Ⅱlevel when ecological security was greater than 0.3 and equal or less than 0.65, andⅢ level when ecological security was equal or greater than 0.65. In addition, this study demonstrated that the pattern of landscape ecological security changed obviously. From 1993 to 2000, the I level area had no noticeable change, but the Ⅱ and Ⅲ level area were converted to each another. From 2000 to 2010, theⅠand Ⅱlevel area were expanded, which were converted from the Ⅲ level area. In the past 20 years, the gravity center of landscape ecological security of cultivated land had transferred to the adjacent regions of Qinhuangdao city. It indicated that the landscape ecological security of coastal area had been increased obviously. The reduction of rainfall and runoff, with the rapid increase in economy and population, and governmental policy decision all had a profound effect on the landscape ecological security variation of cultivated land. This study applied landscape pattern index to describe the landscape structure of cultivated land in ecological security study. The studies on ecological security evaluation of cultivated land are conductive to protection of fragile ecological environment and local sustainable development of cultivated land resources.