Study On Landscape Pattern Fragmentation Of Land Use In Sichuan Province In Recent 10 Years

With the increase of population and economic growth,the land use has been influenced fiercely by human activities,at the same time,the land use pattern has changed,which make the landscape fragmentation degree and the landscape heterogeneity increased.Sichuan is an important province in Western China,the population is large and imbalanced in space,and the economic development is quite different in regions.Because of the great disparity in the economic and technical level,the methods and intensity of land use are not the same in different places,which lead landscape pattern to change greatly,and will have strong influence in the economic trend and the ecological environment in the future.The study takes Sichuan Province as research object,uses MODIS of Sichuan Province in 2005,2010 and 2015,based on the analysis of changes of land use/cover in 2005-2010 and2010-2015,studies land-use landscape pattern fragmentation and spatial distribution characteristics in 3 periods,discusses the infulencing factors that make the forest land patches fragmental.By studying the land use/cover and landscape pattern changes,and analysing the relationship between landscape fragmentation and influence factors,it could provide reference for sustainable land use and maintenance of regional ecological balance.The main results show as follows:(1)From 2005 to 2015,the land use/cover area in Sichuan is sorted by size:forest land,grassland,cultivated land,unused land,construction land and water area.The area of cultivated land is reduced first and then increased,the area in 2015 reached 73573.26 km²;the area of forest land and construction land continue to increase,and their area reached205739.72 km² and 17054.45km² in 2015;the area of unused land,grassland and water area continue to decrease,and their area reached 30217.14 km²,148852.42 km² and10002.39 km² in 2015.(2)From 2005 to 2015,the landscape fragmentation indexes of Sichuan Province in class level show:the number of patches(NP),the number of patch fragmentation index(FN₂),the edge density(ED)and the mean pahch size(MPS)show an increase trend,indicating that the human activities have made the land patches fragmented.Among these indexes,the trend of increase in 2010-2015 is more obvious than that in 2005-2010.The shape fragmentation index(FS₁)and area weighted shape fragmentation index(FS₂)have not changed much,indicating that land use types in class level have little change about shape fragmentation.The landscape shape index(LSI)increases,indicating that the patch edges are becoming complex and able to disturbed by outer influence factors.(3)From 2005 to 2015,the landscape fragmentation indexes of Sichuan Province in landscape level show:the number of fragmentation index(FN₁),divide index(DIV),interspersion and juxtaposition index(IJI),Shannon diversity index(SHDI),the largest patch index(LPI)and cohesion index(COHESION)decreases,indicating that the patch distribution becomes fragmented as time goes on.(4)From 2005 to 2015,the landscape fragmentation indexes of Sichuan Province in spacial distribution show:the low value of the number of fragmentation index(FN₁),divide index(DIV),interspersion and juxtaposition index(IJI),Shannon diversity index(SHDI),the largest patch index(LPI),and the cohesion index(COHESION)are mainly distributed in Bazhong,Guangyuan and Dazhou,as well as the west of Ganzi and in the southern part of Liangshan.It shows that the landscape structure of these areas is complex,the integrity of structure is poor,and the number of patches is large,as a result the fragmentation is aggravated.(5)The cluster analysis of landscape level index in 2005,2010 and 2015 shows that the high aggregation area is mainly distributed in the northeast and the south of Sichuan Province.In 2005,the high aggregation is mainly distributed in the northeast,including Bazhong,Guangyuan,Dazhou and Luzhou,and the middle of the province,including Meishan,Leshan and Yaan,and parts of Liangshan in the southern part of the province;in2010,the high aggregation reduced in middle of the province,in 2015 the high aggregation decreased in the northeast and southern parts,and increased in the middle and southeastern regions.The distribution of low aggregation areas is not obvious in 2005 and 2010,but it is more separated in Ganzi and Aba,indecating that the areas of fragmentation are not serious and the areas are reduced.(6)From 2005 to 2015,the factors influencing the fragmentation of forest land landscape patterns on class level are ground average GDP,elevation,fire area,rearing area,afforestation area,and agricultural population density.The main influencing factors of the patch number(NP)changing are the ground average GDP and the afforestation area;the main influencing factors of the boundary density(ED)changing are the ground average GDP and the agricultural population density;the main influencing factors of the landscape shape index(LSI)changing are the agricultural population density and the ground average GDP,and the main influencing factors of mean patch size(MPS)are ground average GDP and population density.