基于RS和GIS的深圳市土地利用/覆被变化及碳效应分析

基于多时相遥感影像数据,结合能源消费数据和相关经验数据,利用RS和GIS技术分析了2005—2013年广东省深圳市土地利用/覆被变化情况及其导致的碳效应变化。结果表明:近9a来深圳市土地利用变化十分显著,作为区域内最大碳汇的林地面积下降14.96%,净减少量为11 524.32hm~2,而最大碳源的建设用地面积上升23.26%,净增加量高达18 565.39hm~2,其他用地类型如耕地、草地、水域面积分别减少37.17%,31.98%,11.56%,未利用地面积增加713.28%;从方向性来看,9a内研究区土地转移过程中既有生态正向演变,也同时存在生态逆向演变过程。既有耕地的非农化,也包括建设用地的复垦退出,整体呈现非单向性的复杂特征;从数量特征来看,林地是最大的转出者,耕地次之,而建设用地是最大的接收者;基于碳效应测算模型,计算得出研究区近9a来土地利用/覆被变化造成的碳排放增量超过碳吸收增量高达85.41万t,说明人为活动和自然因素共同作用下的土地利用格局变化直接影响着区域碳循环过程,深圳市低碳城市建设目标面临严峻挑战。

Land Use/Cover Change and Carbon Effect in Shenzhen City Based on RS and GIS

Based on the multi-temporal remote sensing images,combined with energy consumption data and relevant empirical data,RS and GIS technologies were employed to analyze the land use/cover change and its impact on carbon cycle in Shenzhen City,Guangdong Province from 2005 to 2013.Results show that land use in Shenzhen City has undergone a remarkable change in the recent 9 years.The area of forest land,the largest carbon sink in the region,has decreased by 14.96％,and its net reduction is 11 524.32 hm2.In contrast,construction land,the largest carbon source,its area has increased by 23.26％,and its net increase reaches up to 18 565.39 hm2.As for other land use types such as cultivated land,grassland and water area,their areas have reduced by 37.17％,31.98％ and 11.56％,respectively,while unutilized land area has been boosted by 713.28％.In the aspect of direction,the process of land conversion within study area in the recent 9 years includes both positive ecological evolution and adverse ecological evolution.Besides,it also comprises non-agriculturalization of cultivated land together with reclamation and exit of construction land.In general,land conversion process shows complicated characteristics of non-unidirectionality.From the perspective of numerical characteristics,forestland is the largest contributor in area transfer,followed by cultivated land,while construction land is the largest acceptor.Based on the carbon effect calculation model,we estimate that,caused by land use/cover change in study area in the recent 9 years,carbon emission increment has outnumbered carbon absorption increment by 854 100 tons.The fact reflects that land use pattern change under the influence of human activities and natural factors directly affects regional carbon cycle.Thus,Shenzhen City has to confront a severe challenge in low-carbon city construction project.