Study On Landscape Pattern Change Of Cultivated Land In Changsha City

As the material basis of human survival,the stability of cultivated land resources quality and quantity is the important guarantee of ensuring social economic growth and realizing sustainable development.With the economic growth,the situation of arable land protection becomes more and more serious,the contradiction between people and land is becoming more and more prominent,so to ensure the sustainable use of arable land has become an important research topic in contemporary society.With using GIS spatial analysis technology and combining the theory of landscape ecology index and fractal theory,this paper not only analyzed the landscape pattern but also explored the characteristics and regularity of landscape pattern change of Changsha cultivated land in 1990-2015.According to the process and characteristics of urbanization development in Changsha,the characteristics and reasons of landscape pattern change in different cities and countries are compared and analyzed,which provides some reference for rational utilization and protection of cultivated land resources.The main conclusions of the study are as follows:(1)In the 1990-2015,arable land area of Changsha was decreasing,the largest reduction area is in the center;The number of cultivated land patches changed less 2000 years ago,and the number of farmland patches increased rapidly after 2005,among which the number of farmlandpatches rose most in the Wangcheng district.The largest index changes greatly,the area of arable land is shrinking,and the area of Changsha County has the biggest decrease.With the increase of edge curvature and length,the influence of arable land is more intense,the average distance of soil patches and the degree of adhesion are decreasing,and the fragmentation is increasing.The landscape fractal dimension of arable land is decreasing,and the shape is more and more simple.The increase of edge density index is obvious in Central District,Wangcheng District,Changsha County and Central of Liuyang City,the fragmentation rate of cultivated land in this area is faster than that in other areas.The average shape index of cultivated land decreased significantly in Southern Central District and Wangcheng District,the cultivated land in this area has been greatly affected by human activities.The fractional index of cultivated land patches decreased in southeast of Liuyang City and west of Ningxiang City,the connectivity of cultivated land in this area has been enhanced.(2)During the 1990-2015,the increase of arable land in Changsha mainly originates from woodland,followed by the reclamation of the water surface of the pits,which accounted for 76.92% of the total amount of arable land,and mainly located in Liuyang,Ningxiang and Wangcheng district.The farmland mainly flows to the construction land,the secondly is the woodland and the water,in which the construction land occupies288.93 square kilometers,and mainly locates in the central city and the lookout city and Changsha county.(3)The change of farmland landscape pattern in Changsha is affected by the expansion of construction land,and the loss of arable land is consistent with the area occupied by construction land.Mainly concentrated in the central city and Wangcheng district,because of the continuous expansion of urban areas,surrounding large tracts of arable land into construction land,the surrounding traffic network construction made the arable land cut seriously.At the same time,the Changsha population increase,further aggravate the farmland landscape pattern change,the population center and the farmland center of gravity migration are negatively correlated in space.The new and expanding of main truck roads,the new and migration of school or government office area and other government actions also are important factors of the change of cultivated land landscape pattern in Changsha.From the topography perspective,the slope has infected on the change of cultivated land landscape pattern,the Changsha arable land mainly distributes in the gentle area with the slope less than 5°,and the landscape change is mainly concentrated in the flat area.