测定了干旱沙区不同年限植被恢复区土壤0～5（包括结皮层）、5～10和10～20 cm颗粒组成分布、土壤有机碳（Soil organic carbon, SOC）和全氮含量，并分析了土壤颗粒组成分布中沙粒和粘粉粒含量变化与土壤SOC和氮含量间的关系，探讨植被恢复过程中SOC和氮变化规律。研究表明，干旱沙区植被恢复过程中，SOC和全氮含量存在明显的固存效应，这种效应不仅表现在植被恢复的时间上，也表现在土壤垂直分布上。植被恢复区SOC和氮含量随恢复时间的延长呈增加趋势，在垂直方向上呈降低趋势。土壤极细沙（0.1～0.05 mm）和粘粉粒含量（<0.05 mm）的时间和空间变异与SOC和氮有着相似的趋势。而沙粒含量（0.5～0.1 mm）则随植被恢复时间增加和土层深度的增加呈降低趋势。土壤中极细沙粒（0.1～0.05 mm）和粘粉粒含量（ <0 .05 mm）分别与SOC和氮含量有显著正相关关系（p<0.01），而沙粒含量（0.5～0 .1 mm）与SOC和氮含量呈显著负相关（p<0.01）。从植被恢复或者荒漠化逆转角度阐明了干旱沙区土地利用的变化导致的土壤保护性碳组分的增加是土壤碳储量汇功能增加的体现。在研究区域，有机碳和全氮因土壤粘粉粒和极细沙而积累的定量关系可以用线性方程很好地预测，从而为更好地估算荒漠化逆转过程中不同阶段碳汇量提供了依据。而植被恢复中土壤SOC和氮与土壤颗粒间的结论加深了荒漠化逆转过程中土地利用方式的改变对气候变化响应的陆地生态系统碳循环过程与机理的理解，明确了我国广泛在干旱沙区实施区域治理对全球大气CO2汇的贡献。植被恢复过程中，表征土壤肥力特征的SOC和氮在时间和空间上的变异对植被演变的影响，以及土壤物理稳定性的增强对土壤抗风蚀能力的贡献。从另一个方面阐述了植被恢复过程中土壤和植被间的这种相互关系及其对生态环境改善的贡献，为探讨干旱沙区荒漠化逆转过程中植物种的选育和合理评价生态环境提供了参考。
Aims It is an important aspect that the soil organic carbon and nitrogen sequestration or release contribute to the soil fertility and atmosphere CO2. However, soil organic carbon and nitrogen dynamics has been argued during the process of desertification, the soil organic carbon and nitrogen is rarely explain during the re-vegetation process in the arid desert region. Furthermore, there have some debates about the relation between the soil particle content and soil organic carbon and nitrogen. So, the following questions toe will be sought (a) Does soil organic carbon and nitrogen content during the re-vegetation process differs in time and space? (b) How is there the relation between soil particle content and the soil organic carbon and nitrogen content?
Methods The distributions of particle size fractions, organic carbon and total nitrogen content in soils profile of 0-5 cm (include soil crust), 5-10 cm, and 10-20 cm at different years since re-vegetation were analyzed.
Important findings The results showed that soil organic carbon and nitrogen contents increased with time since re-vegetation but decreased with soil depth. Fine sand (0.1-0.05 mm), silt and clay (<0.05 mm) content showed similar temporal and spatial patterns. However, sand (0.5-0.1 mm) content decreased with time since re-vegetation and soil depth. Soil organic carbon and nitrogen contents positively correlated with the contents of fine sand and silt+clay (p<0.01) and negatively correlated with the sand content (p<0.01).From the point of view of the re versed desertification or re-vegetation process, our results suggest that change of land use can result in carbon sequestration because of the increment of soil protected carbon content in arid desert region. The spatial and temporal changes of soil organic carbon and nitrogen contents as indices for soil fertility may positively feed back to vegetation succession.