摘要:
整合了青海省东部地区33 092 km2多目标区域地球化学调查和土地质量地球化学调查数据,估算了研究区表层土壤有机碳总储量为171.16 Mt,平均有机碳密度为5 172.14 t/km2,并分析了表层土壤有机碳空间分布特征和主要影响因素。结果表明:在高山和中低山地貌、草原土和草甸土土壤类型、残坡积物成土母质、林草地和高山稀疏植被区土地利用、草原和森林系统下,表层土壤有机碳平均密度明显偏高,在沙漠地貌、风沙土土壤类型和风成砂成土母质区表层土壤有机碳密度最低,说明地形地貌(海拔高低)、成土母质、气候及植被均对表层土壤有机碳密度及分布规律产生影响。与青海省土壤第二次普查数据有机碳储量对比,在过去20多年里青海东部表层土壤共释放约53.21 Mt有机碳,表明在长期耕种、过度砍伐和放牧等人类生产活动影响下土壤有机碳已出现一定程度的下降。
Abstract:
This study integrated the data of both the multi-purpose regional geochemical survey and land quality geochemical survey covering an area of 33 092 km2 in eastern Qinghai. Based on these data, the total organic carbon storage of topsoil in the study area was estimated to be 171.16 Mt, with an average organic carbon density of 5 172.14 t/km2. Moreover, this study analyzed the spatial distribution and main influencing factors of organic carbon in topsoil. As indicated by the results, the average density of organic carbon in topsoil is significantly high in high and middle-low mountains, grassland and meadow soils, soil parent materials of eluvial-slope deposits, forest grasslands, and alpine sparse vegetation areas, grassland and forest and is the lowest in deserts, aeolian sandy soil, and soil parent material areas of aeolian sands. This finding means that factors including topography (altitude), soil parent materials, climate, and vegetation affect the density and distribution of organic carbon in topsoil. Compared with the organic carbon storage revealed by the second general detailed soil survey in Qinghai, 53.21 Mt of organic carbon has been released from the topsoil of eastern Qinghai in the past 20 years. This result indicates that the soil organic carbon has decreased to a certain extent under the influence of human production activities such as long-term cultivation, overcutting, and overgrazing.
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