腾格里沙漠东南缘植被恢复对土壤有机碳矿化的影响

Effects of revegetation on soil organic carbon mineralization in the southeastern fringe of the Tengger Desert

以流沙为对照,研究腾格里沙漠东南缘建植于不同年代(1956、1973和1987年)人工固沙植被区土壤有机碳(SOC)矿化过程及其对水分和温度的响应特征.结果表明,沙区植被恢复显著促进SOC矿化过程,固沙植被建立62 a后, SOC矿化平均速率、最大速率和累积碳释放量分别是流沙的4.12、4.04和4.12倍.植被恢复对SOC矿化的促进作用与水分和温度密切相关, 10%含水质量分数时, SOC矿化平均速率、最大速率和累积碳释放量分别是5%含水质量分数时的1.91、2.27和1.91倍;25℃时, SOC矿化平均速率、最大速率和累积碳释放量分别是10℃的2.02、3.11和2.02倍.因子分析表明, SOC和全氮是SOC矿化的主要影响因素.总体上,植被恢复促进SOC矿化过程及土壤碳周转,降低SOC中可矿化碳的比例,有利于碳的固存,是植被特征和土壤理化性质等环境因子变化共同作用的结果.

Soil organic carbon mineralization(SOCM) and its response to the dynamics of soil water content(SWC) and soil temperature(Ts) of incubation in the revegetation areas along a chronosequence(established in 1956, 1973 and 1987, respectively) in the Tengger Desert were investigated by taking the mobile sand as control through lab incubations. The results showed that significant differences were found in SOCM rates among different sites. 62 years after the shrubs being planted, the average and maximum SOCM rates and cumulative carbon release(CCR) were 4.12, 4.04 and 4.12 times greater than those of the mobile sand, respectively. The effects of revegetation on SOCM were closely related to SWC and Ts of incubation. The average and maximum SOCM rates and CCR with 10% of SWC were 1.91, 2.27 and1.91 times greater than those soil with 5% of SWC, respectively;the average and maximum SOCM rates and CCR in 10 ℃ incubation were 2.02, 3.11 and 2.02 times more than those in 25 ℃. During vegetation restoration, soil organic carbon and nitrogen were the main factors affecting SOCM. Our understanding of the effects on soil carbon mineralization suggested that revegetation in desert areas could promote the SOCM and the turnover of soil carbon, reduce the proportion of mineralizable carbon in soil carbon pool and improve soil carbon sequestration capacity. The dynamic patterns of SOCM during vegetation restoration were regulated by vegetation attributes in combination with soil physicochemical properties.