江苏省土地利用变化对陆地生态系统碳储量的影响

Land Use Change and Its Influence on Carbon Storage of Terrestrial Ecosystems in Jiangsu Province

土地利用变化是影响陆地生态系统碳储量变化的重要驱动因素,目前相关研究主要集中在土地利用变化对单一生态系统的影响,如土壤生态系统、森林生态系统、农地、草地生态系统等,本文以江苏省为研究区域,综合考虑了整个生态系统来探讨土地利用变化对碳储量的影响。文中涉及到的数据包括土地利用数据、土壤数据、植被数据。利用ArcGIS9.3分析1985到2005年江苏省土地利用变化,根据不同的方法,分别计算了江苏省不同土地利用类型的土壤碳储量和植被碳储量,并分析其对土地利用变化的影响,主要结论如下:①江苏省陆地生态系统总碳储量为975.72Tg,其中土壤碳储量为922.03Tg,占有机碳总储量的94.5%,土壤平均碳密度为9.41kg/m2,植被碳储量为53.69Tg,占有机碳总储量的5.5%,植被平均碳密度为1.791kg/m2;②1985-2005年江苏省陆地生态系统有机碳储量共减少9.73Tg,其中土壤有机碳储量减少7.54Tg,植被有机碳储量减少2.19Tg,土地利用变化造成了有机碳的释放,释放量占江苏省陆地生态系统有机碳储量的1%;③建设占用耕地是引起碳储量变化的主要原因,但总体而言,人类土地利用活动对江苏省陆地生态系统总碳储量平衡的扰动并不大;④应通过加强耕地保护、增加碳汇和土地利用结构优化等方式来降低人为活动对自然碳过程的影响。

Land use change is a main driver to terrestrial ecosystems carbon storage. Most recent studies seem to focus only on a single ecosystem, such as soil ecosystem, forest ecosystem, farmland ecosystem, and grassland ecosystem. Data about land use, soil organic carbon, and vegetation were jointly used to analyze effect of land use change on carbon storage of the whole terrestrial ecosystem in Jiangsu Province. Land use change data were derived from remote sensing images acquired in 1985 and 2005; soil organic carbon data were provided by the Geological Survey of Jiangsu Province, including 24 186 soil samples which covers the whole area of Jiangsu; data of forest ecosystems were obtained from the fifth forest inventory; crop yield data of farmland ecosystems were provided by Statistical Yearbook of Jiangsu Province, 2006; and data of grassland ecosystems were obtained from the existing studies. This study calculated soil carbon storage and vegetation carbon storage for different land use types. Using the spatial analysis function of ArcGIS 9.3, land use change was derived. Effect of land use change on organic carbon storage of terrestrial ecosystems was analyzed. Major findings are as follows： 1） the terrestrial ecosystem carbon storage of Jiangsu Province was 975.72 Tg, in which soil carbon storage was 922.03 Tg, accounting for 94.5% and vegetation carbon storage was 53.69 Tg, accounting for 5.5%. The average soil carbon density in Jiangsu Province was 9.41kg/m2 while the average vegetation carbon density is 1.79kg/m2; 2） for the reason of land use change, carbon storage decreased by 9.73Tg from 1985 to 2005, accounting for 1% of the total decrease. Soil carbon and vegetation carbon were 7.54 Tg and 2.19 Tg, respectively; 3） expansion of construction land was a main factor resulting in carbon storage decrease. In general, there was only slight disturbance of land use change induced by human activities on terrestrial carbon storage; and 4） in the future, some measures should be taken to reduce human impacts on natural carbon processes, such as strengthening cropland protection, increasing carbon sinks, and optimizing land use structure.