1980s-2010s内蒙古草地表层土壤有机碳储量及其变化

以我国内蒙古草原为研究区域,结合1982-1988年第二次土壤普查资料以及2011-2012年实地考察数据,构建了基于遥感数据和土壤数据的区域表层土壤有机碳储量估算方法,对研究区1980s和2010s表层土壤有机碳储量、空间分布特征及其变化进行研究,结果表明：(1) 1980s、2010s内蒙古草地表层土壤 (0~20 cm) 有机碳储量分别为2.05 Pg C、2.17 Pg C,土壤有机碳密度约为3.48 kg C·m^-2、3.69 kg C·m^-2,其空间分布上呈现从草甸草原、典型草原、荒漠草原逐渐降低的特征;(2) 1982-2012年间,内蒙古草地表层土壤有机碳储量略有增加,但增加幅度较小,其中草甸草原和典型草原表层土壤有机碳储量增加,荒漠草原则表现为减少。研究结果将为研究区因地制宜地采取固碳措施,实现草地可持续管理提供科学参考。

Topsoil organic carbon storage and its changes in Inner Mongolia grassland from the 1980s to 2010s

Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the extent well as its change of soil organic carbon (SOC) storage is of great importance. Based on soil data from the second soil survey of China and field survey during 2011-2012, this paper studied spatial distribution and changes of topsoil (0-20 cm) organic carbon storage in Inner Mongolia grassland between the 1980s and 2010s, by using the regression relation between soil data and remote sensing data. The results showed that (1) the SOC storage values in Inner Mongolia grassland in the 1980s and 2010s were estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m^-2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total. The spatial distribution showed a decrease trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient. (2) SOC variations during 1982-2012 were estimated to be 0.12 Pg C, at 7.00 g C·m^-2·yr^-1, which did not show a significant change. This indicates that SOC storage in grassland ecosystem of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon of different grassland ecosystems showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe, as a carbon sink, had sequestered at 0.15 and 0.03 Pg C, respectively, while desert steppe, as a carbon source, had lost 0.06 Pg C. It is concluded that SOC storage in grassland ecosystem may respond differently to climate change, which is related to vegetation type, regional climate type and grazing intensity. These results will provide references for decision makers to find proper resolutions to protect grassland soil resource.