摘要:植被恢复与重建是沙区退化土地修复的有效途径，是生物土壤结皮（Biological Soil Crusts，BSCs）拓殖和发育的关键影响因素。采用室内恒温培养-碱液吸收法研究了腾格里沙漠东南缘不同恢复年限固沙植被区BSCs及其下层0-5 cm土壤的碳矿化特征，分析了其与水分及土壤理化性质的关系。结果表明：BSCs及其下层土壤有机碳的瞬时速率、最大和平均矿化速率以及累计释放量均随着恢复年限的延长而增大，同一植被区表现为BSCs大于下层0-5 cm土壤（P<0.001）。土壤含水量的增加显著促进了有机碳矿化过程（P<0.001），土壤水分含量从5%增加到20%时，BSCs有机碳的平均和最大矿化速率及累计释放量分别增加了1.48-2.08倍、1.60-2.00倍和1.48-2.08倍，下层土壤分别增大了1.36-2.08倍、1.21-2.00倍和1.36-2.08倍。土壤电导率、有机碳和黏粒含量是影响有机碳矿化的主要影响因素。结果表明沙区植被恢复与重建背景下BSCs的发生发展促进了土壤碳矿化过程，而BSCs参与的碳循环过程受其理化属性及水分等环境因子的共同影响。



Abstract:As an effective measure to curb land degradation in desert regions, revegetation plays a key role controlling the colonization and settlement of biological soil crusts (BSCs), which would modify the processes of soil formation and carbon cycle. Recently, mineralization of BSCs and their subsoils along with the succession of sand-fixing vegetation were still poorly understood, which may to a certain extent limits the accurate estimation of the ecological effects of sand-fixing vegetation. In this study, the carbon mineralization of BSCs and the 0-5 cm soil under BSCs in the vegetated areas at different revegetation ages in the southeastern edge of the Tengger Desert were investigated by using the indoor-incubation-alkali-absorption method, and the relationships between the carbon mineralization rates and water treatments and soil physicochemical properties were analyzed. The results showed that: the instantaneous (IR), maximum (MR) and average mineralization (AR) rates and the amount of cumulative C release (CCR) of BSCs and subsoils all increased with the increasing stand age, and they were significantly greater in BSCs than those in the subsoils (P<0.001). The increase of soil water content (SWC) significantly promoted soil organic carbon mineralization (P<0.001). As the soil water content increased from 5% to 20%, MR and CCR of the BSCs increased by 1.48-2.08 times, 1.60-2.00 times, and 1.48-2.08 times, respectively, while those of the subsoils increased by 1.36-2.08 times, 1.21-2.00 times, and 1.36-2.08 times, respectively. Soil electrical conductivity, organic carbon and clay content are the main factors affecting the mineralization of organic carbon. Our results suggested that the occurrence and development of BSCs induced by the revegetation promoted soil carbon mineralization in desert regions, and the carbon cycling process in which BSCs are involved is regulated by environmental factors such as BSCs' physicochemical properties and water regimes.





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