3S-Based Analysis On Patterns And Driving Forces Of Desertification Land In Typical Areas Of Chengde

Chengde is one of the areas which are seriously harms by the land desertification,especially in Jieba and Bashang Region which were ecologically fragile zone.It is great significance to study the land desertification and driving factors,in order to formulated of specific measures for desertification prevention,constructed reasonable desertification control project,scientific use and protection of local resources to ensure the sustainable development of society and environment.Therefore,based on two desertification data extracted with the support of ArcGIS from the remote sensing image in Jieba and Bashang Region of Chengde in 2009 and 2014,analyzed the change of desertification land spatial and temporal pattern,transfer matrix and Markov model were used to analyzed the transfer of desertification land and land use types,predict the land use in 2019 based on the land use pattern in 2014,space processing were used to analyzed the driving factors of desertification based on the land use types and terrain information.The main results were summarized as follows:(1)Evolution of spatial and temporal pattern of desertification land in different regionsThe desertification land was concentrated in west of Jieba region central,mainly in light desertification.By 2014,the area of non desertification had increased by 759.39hm~2,the area of light and severely desertification had respectively decreased by 560.89 hm~2 and1872.58 hm~2,the area of moderate desertification had increased by 1624.36 hm~2,and the total area of desertification land had decreased by 809.11 hm~2.The main types of desertification land in this area was fixed sand land,followed by sandy cultivated land,and the desertification area were almost covered by the two types.The land with obvious tendency of desertification land was concentrated in the west of central.The area change of the fixed sand was the most obvious which had decreased by 691.74 hm~2 over the past five years.Cultivated land,woodland and grassland were the main land use types.Grassland was distributed in the west,mixed with cultivated land.Woodland was concentrated in the east and gradually extended to the south and southwest.The area of woodland was increased by 40565.04 hm~2,and grassland was decreased by 52349.72 hm~2.The distribution of desertification land in Bashang Region was continuously expanded from the initial center to the periphery.The degree of desertification mainly in light.The light,moderate and severe desertification area were increased by 839.89 hm~2,337.10 hm~2and 158.93 hm~2 respectively.The main types of desertification land in this area was fixed sand land.The land use type was mainly grassland in 2009.By 2014,the area of cultivated land,woodland and grassland had little difference,the area of grassland was decreased by4869.61 hm~2 and cultivated land and woodland was increased by 1180.71 hm~2 and 934.20hm~2 respectively.(2)Evolution model and prediction of desertification land in different regionsThe main shifting direction between different degrees of desertification from 2009 to2014,the probability of transferring from severe to moderate had reached 0.661,and from moderate to light had reached 0.635 in Jieba Region,the probability of transferring from moderate to light had reached 0.422,and from severe to moderate and light had reached0.101 and 0.393 respectively in Bashang Region.The transfer of different desertification types was from semi-fixed sand land to fixed sand land.The mutual conversion between cultivated land,woodland and grassland was the main type of land transfer,the probability of transferring from grassland to woodland had reached 0.317 in Jieba Region,the probability of transferring from woodland to grassland had reached 0.290,from grassland to woodland had reached 0.283 in Bashang Region.By 2019 forecast,the area of woodland would increased by 12923.88 hm~2,and cultivated land,grassland would decreased by 14642.30 hm~2 and 4210.04 hm~2 respectively in Jiaba Region,the area of woodland would increased by 120.01 hm~2,and grassland would decreased by 108.66 hm~2.(3)The influence of driving factors on land desertificationThe land use types was more significant than terrain factors on desertification.Cultivated land,woodland and grassland were the key factors on land desertification,and the desertified area of grassland was the most severe,which had a significant impact on desertification.In 2009 and 2014,the desertification area of grassland was 44947.08 hm~2and 32975.52 hm~2 in Jieba Region,was 3164.20 hm~2 and 3255.29 hm~2in Bashang Region.The desertification area of cultivated land and woodland was the second,which has a little influence on desertification.The altitude grade of II and III have great influence on desertification land,nearly70%of desertification land was distributed at level III in Jieba Region,nearly 80%of desertification land was distributed at level II II in Bashang Region.The slope grade of I has great influence on desertification land,nearly 70%in Jieba Region and nearly 90%in Bashang Region.The impact of sunny slope on desertification land was grate influence than shady slope,the desertification area on the shady slope is slightly than the sunny slope,but the moderate and severe desertification was serious in the sunny slope in Jieba Region.In Bashang Region,the desertification area on the sunny slope was greater than that of shady slope.