毛乌素沙地杨柴灌木林恢复演替过程中土壤活性有机碳组分变化特征

土壤活性有机碳是土壤有机碳(SOC)的活性部分，是衡量土壤质量和健康状况的重要指标，能够反映植被恢复演替过程中土壤环境的早期变化。但在SOC贫瘠的沙地，长期恢复演替如何影响土壤活性有机碳组分尚不清楚。本研究以毛乌素沙地杨柴人工灌木林为研究对象，分别选取未造林(CK)与造林年限9 a、18 a和30 a的杨柴人工灌木林，探究毛乌素沙地杨柴人工灌木林恢复演替过程中土壤可溶性有机碳(DOC)、微生物量碳(MBC)、易氧化有机碳(ROC)和SOC变化规律。结果表明：(1)毛乌素沙地杨柴灌木林随恢复演替年限增加土壤固碳能力增强，但在恢复演替18 a时出现转折点，恢复演替18—30 a时土壤固碳速率相对减缓；(2)表层0—10 cm土壤DOC、MBC和ROC对恢复演替响应较为敏感，恢复演替过程中表层土壤活性有机碳各组分含量逐渐升高；(3)恢复演替年限并未对土壤活性有机碳占SOC比例产生显著影响，同时也未显著改变碳库活度。综上所述，毛乌素沙地杨柴灌木林恢复演替有助于土壤活性有机碳和SOC积累，但长期恢复演替是否持续对土壤活性有机碳固持产生积极作用仍需进一步研究。

Changes of soil active organic carbon components during restoration and succession of Hedysarum mongolicum shrub forest in Mu Us Sandy Land

Soil active organic carbon is the active part of soil organic carbon (SOC). Soil active organic carbon, which is an important index to measure soil quality and health status, can reflect the early changes of soil environment in the process of vegetation restoration and succession. However, in the barren sandy land of SOC, the influencing mechanism of long-term restoration succession affecting soil active organic carbon composition is still unknown. This study took Hedysarum mongolicum artificial shrub forest in Mu Us Sandy Land as the research object, selected Hedysarum mongolicum artificial shrub forest with no afforestation (CK) and afforestation life for 9 a, 18 a and 30 a, respectively. We explored the changes of soil dissolved organic carbon (DOC), microbial biomass carbon (MBC), readily oxidizable organic carbon (ROC) and SOC during the restoration and succession of Hedysarum mongolicum artificial shrub forest in Mu Us Sandy Land. The results showed that: (1) the soil carbon sequestration capacity of Hedysarum mongolicum shrub forest in Mu Us Sandy Land increased with the increase of restoration succession years. But there was a turning point in the restoration succession for 18 a, and the soil carbon sequestration rate slowed down in the restoration succession for 18-30 a; (2) DOC, MBC and ROC of topsoil 0-10 cm were sensitive to restoration succession, and the contents of active organic carbon in topsoil increased gradually during restoration succession; (3) The restoration succession years did not have a significant effect on the ratio of soil active organic carbon to SOC, nor did it significantly change the carbon pool activity. To sum up, the restoration succession of poplar wood shrub forest in Mu Us Sandy Land is conducive to the accumulation of soil active organic carbon and SOC. Whether the long-term restoration succession has a positive effect on soil active organic carbon sequestration need to study further.