成都平原及其周边区域土地利用碳排放效应及空间格局

Effect of land use changes on carbon emission and its spatial patterns in Chengdu Plain and its surrounding area, western China, from 1990 to 2010

土地利用变化的碳排放研究对了解人类活动对生态环境的扰动程度及其机理、制定有效的碳排放政策具有重要意义。采用1990—2010年能源消费数据、遥感与GIS提取的土地利用数据,通过构建土地利用碳排放模型,对20 a来成都平原及其周边区域土地利用的碳排放进行了定量分析。结果表明:(1)土地利用变化的碳排放增加3269.37×10~4 t,增长率达137%,呈显著增加趋势。(2)建设用地和林地分别为区域最大的碳源与碳汇。建设用地的碳排放增加3271.55×10~4 t,增长率达139.01%,林地的碳汇减少1.30×10~4 t,减少率达3.12%,但仍占碳汇的99%以上。(3)土地利用的碳排放存在明显区域差异。中部、北部和南部冲积平原(成都市及其第二圈层、绵阳市辖区、绵竹市、乐山市辖区)碳排放大,平原周边区域邻近川西高原山地碳排放小。(4)土地利用结构与碳排放存在一定的相互关系,趋高的碳源、碳汇比导致土地利用的碳源效应远大于碳汇效应。因此,研究区减排的重点应该在保持或增加现有的林地的同时,主要以降低建设用地的碳排放、碳足迹为主。

Analysis of the effects of land use on carbon emissions is important for understanding the mechanisms of carbon emissions, carbon emissions reduction, and climate change mitigation. In this study, we proposed models of carbon emissions for evaluating the carbon budget in the Chengdu Plain, western China, from 1990 to 2010 by estimating carbon sinks and carbon sources based on data of energy consumption and land use changes determined using remote sensing. The results are as follows. （1） Carbon emissions from land use changes significantly increased by 3269.37×104 t or 137%. The increased carbon emissions in Sichuan were associated with the rapid increase in fossil fuel consumption and land use changes. （2） Carbon sources of construction land and carbon sinks of forestland accounted for the largest percentage, respectively. Carbon emissions associated with built-up land were much higher than they were for other land use types. In contrast to the continuous increase in carbon sources, there was a slight overall decrease in carbon sinks, between 1990 and 2010. Carbon emissions increased by 3271.55×104 t or 139.01% from built-up land, but decreased by 1.30×104 t or 3.12% because of the carbon sink from forestland. （3） The regional differences in carbon emissions from land use were obvious. The Chengdu and its second circle-layer, the Mianyang municipal district, Mianzhu, and the Leshan municipal district all had greater carbon emissions in 2010 than in 1990, whereas carbon emissions in the west, northwest, and southwest mountainous regions had lower, or negative net, carbon emissions because of wide-spread cover by forests and grassland. These regions had relatively low fossil fuel consumption, slow urbanization, limited industrial development, and transportation challenges compared to the Chengdu Plain and its surrounding regions. Spatial distributions of carbon emissions in the Chengdu Plain from 1990 to 2010 indicated that carbon emissions increased both in amount and geographic scale with time. （4） There was a certain relationship between the land use structure and carbon emissions. Carbon sources effect of land use was much higher than the carbon sinks effect. Forestland, grassland, areas of surface water, and unused land were carbon sinks, whereas construction land and cultivated land were carbon sources. The rapid increase in carbon sources and slow decrease in carbon sinks resulted in a substantial increase in carbon emissions in Sichuan from 1990 to 2010. Therefore, the focus of carbon emissions reduction in Sichuan should be on keeping or increasing the existing forestland area, while mainly continuing carbon emissions reduction from construction land. Through targeted land use and land management activities, ecosystems can be managed to enhance carbon sequestration and mitigate fluxes in other greenhouse gases.