| An increasing attention has been focused upon carbon storage and its variation ofterrestrial ecosystem which is always being the important and difficult point in thestudy on climate and environment change at a global scale. Moreover, land use/coverchange acts as the key driving factor that affects terrestrial ecosystem carbon cycle.Human activities change the way of land use to much extent, which further leads torevelant change of many natural ecological processes, then vegetation carbon storagechanges obviously. Therefore, it’s necessary to estimate the relationship between landcover change and vegetation carbon storage accurately in order to get a betterunderstanding of influencing mechanism for ecosystem carbon cycle.During the past20years, Gu’an County obtained a rapid economic developmentand sharp urban expansion while land use/cover changed obviously accordingly. Inthis paper, based on the TM remote sensing images of1989,1996,2003and2009,land use/cover change and dynamic variation of vegetation carbon storage from1989to2009in Gu’an County were analyzed using RS and GIS technologies. Furthermore,the dynamic response relationship between them was studied furtherly. The resultswere showed as the following.Firstly, cultivated land always ranked first followed by construction land andforest land during the20years on the distribution scale. Focusing on the variationtrend, cultivated land area decreased at first and then increased afterwards andittotally decreased by361.92hm2for its transfer to forest land and construction landmostly. The area of forest land acquired an increase of1025.88hm2whichdemonstrated the positive effect of afforestation in Gu’an County. What’s more, areaof unused land decreased continuously, which transited tocultivated land and forestland in a large degree. The changing range ability of grassland area was outstandingfor it decreased to zero in2009which showed a variation rate of-100%. For waterarea, its decrease had great relationship with construction projects and lower rainfall.Construction land area showed aremarkable increasing trend continuously. In thepast20years, it had a rise of2951.23hm2mainly transitedfrom cultivated land whilethe contradiction between humans and land was highlighted gradually. During theperiod of2003to2009, the variation rate of land utilization was obviously abnormal that various kind of land had a higher variation rate than the other two periods. Thiscould be explained by the fact that the rapid development of economy and real estateprompted by the capital economic circle radiation led to the sharp change of land useactivities.During this period, total vegetationcarbon storage increased from119.34×103t in1989to122×103t in2009.The increasing range reached2.66×103t which showed“carbon sink” for the vegetation in the study area. To be more detailed, both cultivatedland and forest land carbon storage showed similar trend that decreased at first andincreased afterwards. However, the results were different that forest carbon storageincreased obviously compared with1989while cultivated land carbon storage actedcontrarily. Moreover, grassland carbon storage decreased continuously. The averagevegetation carbon density in the study area of1989,1996,2003, and2009were2.26kg m-2,2.25kg m-2,2.26kg m-2, and2.28kg m-2, respectively. The general trendwas stable.For the conversion among cultivated land, forest land, grassland and other land,the net loss of cultivated land and grassland vegetation carbon storage were0.75×103t and43.36t, respectively while forest land carbon storage acquired a net increase of3.45×103t. The main reason leading to loss of cultivated land vegetation carbonstorage was that cultivated land was occupied for construction on a large scale.Theincrease of forest land area and high NPP had an obvious contribution to vegetationcarbon storage at Gu’an County. In total, there existed a close relationship betweenthetransfer of land cover types and regional vegetation carbon storage. |
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