Study On The Correlation Between Land Use Change And Forest Fragmentation In Hanshan Secondary Forest Region

Based on the remote sensing images of 1991,1996,2001,2006,2011,2016 and 2019 in Hanshan secondary forest area,according to the Regulations of land use dynamic remote sensing monitoring(TD/T1010-2015),the land use types are divided into six categories,i.e.cultivated land,forest land,grassland,construction land,water body and unused land,and the supervision and classification method is used to obtain the land use information of 7 periods.The landscape indexes,such as dynamic degree of land use,comprehensive index of land use degree,change amount of land use degree and number of patches,percentage of patch type,patch density,average patch area,maximum patch index,patch shape index,patch number fragmentation index,patch shape fragmentation and so on,were used to analyze the effects of land use disturbance on landscape The impact of forest fragmentation.The main conclusions are as follows:(1)Forest land and grassland are the main types of land use in Hanshan secondary forest area,the overall change of each region is characterized by "three increases and three decreases".The area of cultivated land increased by 60%.The area of construction land is increasing year by year,which is almost 1.5 times of the initial area.The area of forest land decreased by nearly half in 30 years,and the decrease range increased first and then decreased.The area of cultivated land and construction land increased significantly in 1996,and the area of forest land decreased significantly in 2001.From 1991 to 2019,the degree of land use change in Hanshan secondary forest area increased year by year,and the amount of land use change showed a trend of first increasing,then decreasing and then increasing.The degree of land use change in each county also showed an increasing trend.The degree of land use in keerqinyouyiqian banner increases the most,and that in xiwuzhumuqin banner increases the least.(2)During 1991-2019,the number of forest patches in Hanshan secondary forest area continued to increase,the percentage of patch type gradually decreased,patch density increased,average patch area decreased,maximum patch index decreased,patch shape index increased,patch number fragmentation index increased,patch shape fragmentation index increased.The degree of forest fragmentation increases year by year,the patch area changes from large to small,and the patch shape becomes more and more complex.The degree of forest fragmentation first increased and then decreased,and it began to increase in 1996,and reached the peak of forest fragmentation in 2006.The degree of forest fragmentation increased from west to east.(3)Farmland,grassland and construction land are positively correlated with forest fragmentation,while water body is negatively correlated with forest fragmentation.Construction land has the greatest impact on forest fragmentation,while water body has the least impact on forest fragmentation.The types of land use related to forest fragmentation can be divided into two types:cultivated land,construction land and natural disturbance such as grassland and water.The effect of human disturbance on forest fragmentation is much greater than that of natural disturbance.The degree of forest fragmentation changes with the change range of cultivated land and construction land.After 1996,the area of cultivated land and construction land in secondary forest area increased greatly and continuously,and the degree of forest fragmentation gradually deepened.By 2006,with the decrease of cultivated land and construction land,the degree of forest fragmentation was alleviated,but the degree of forest fragmentation was still declining.Compared with the initial stage of research,the loss caused by forest fragmentation was inevitable.