中文摘要：

沙漠化过程导致草地生态系统的退化和土壤有机碳的流失，增加了陆地生态系统向大气CO2的排放，使退化土地就成为陆地重要的碳源之一。然而，通过有效的沙漠化防治，沙漠化过程能够得到一定程度的控制，退化土地也会得到恢复。沙漠化土地的恢复将是增加陆地碳汇，减少大气CO2的有效途径之一。黄河源区沙漠化土地处于正在发展和强烈发展阶段，沙漠化形势严峻。目前沙漠化土地面积达3519．97km^2，其中轻度沙漠化土地面积占45．82％、中度沙漠化占26．20％、重度沙漠化土地与极重度沙漠化土地面积分别占13．80％和14．18％。我们设想通过沙漠化治理，使极重度、重度、中度沙漠化得到恢复并转变为轻度沙漠化土地，这将使1907．27km^2的沙漠化土地得到恢复。根据目前沙漠化土地土壤有机碳密度，我们初步估计将会有10．25×10^6t的土壤有机碳能够得到固定。在固定的土壤碳中，极重度沙漠化土地、重度沙漠化土地和中度沙漠化土地贡献分别为4％，30％，36％。因此，目前黄河源区沙漠化土地具有较高的固碳潜力，通过沙漠化的有效治理，不仅能够改善区域生态环境，促进区域社会经济的可持续发展，而且将使黄河源区成为陆地碳汇的重要区域。

英文摘要：

Desertification resulted grassland ecosystem deterioration and soil organic matter lost, leading to terrestrial carbon being released to the atmosphere. Therefore, degraded land would become a major carbon source. However, through effective measures for combating desertification, desertification process could be controlled to some extent and the degraded lands could be restored. Restoring desertified lands would be an alternative approach to sequester the carbon from atmosphere. If we assume that most severe, severe, moderate desertified lands can be rehabilitated and converted to mild desertified land through combating desertification using rational land use, the total 1 907.27 km^2 of various types of desertified lands could be rehabilitated in the headwater area of the Yellow River. Based on the present organic carbon content in desertified land, we could make some preliminary estimates of total 10. 25 × 10^6 t organic carbon can be fxed in the soil. Of these fixations most severe, severe, moderate desertified lands would contribute, respectively, 34%, 30%, 36%. Therefore, present desertified lands have potential to sequestering carbon from atmosphere through rehabilitating desertified land.