塔里木盆地北缘绿洲不同土地利用方式下土壤有机碳含量及其碳矿化特征

目的]探讨土地利用方式对土壤有机碳含量及碳矿化的影响,为塔里木盆地北缘绿洲土壤生态系统的保护和恢复建设提供理论依据。方法]基于野外采样和室内培养试验,分析土壤有机碳含量的基本特征,利用回归分析法拟合出土壤有机碳矿化动态变化过程。结果]矿化累积释放的CO2含量大小依次为:果园棉田人工林弃耕地荒草地盐碱地沙地。不同土地利用方式土壤有机碳矿化反应趋势相同,1~6d为快速分解阶段,日均矿化量高但反应时间短,6~28d为缓慢分解阶段,动态变化与前者相反。有机碳矿化率大小依次为:沙地荒草地盐碱地弃耕地人工林棉田果园,沙地最高,达(10.36±0.24)%,表明沙地土壤有机碳稳定性最差,而果园具有较强的固定有机碳能力。结论]土地利用方式对土壤有机碳矿化及其固碳能力均有显著影响。

Soil Organic Carbon Content and Carbon Mineralization Characteristics Under Different Land Use Types in Northern Tarim Basin

Objective] Illustrating the effects of land use change on soil organic carbon(SOC) content and SOC mineralization, to provide theoretical basis for soil ecosystem preservation and restoration of oasis in the northern marginal zones of the Tarim Basin.Methods] Based on field sampling and laboratory incubation experiment, the basic characteristics of SOC content were analyzed. Regression analysis was used to investigate the dynamic change process of SOC mineralization.Results] The accumulative amounts of SOC mineralization of different land use types ranked as:orchard > cotton > artificial forest > abandoned farmland > barren grassland > saline-alkali land > sandy soil. The chronical trends of SOC mineralization of different land use types were almost the same during the cultivation period. The daily SOC mineralization rate involved two stages of fast(1 to 6 d) and slow (6 to 28 d) decomposition. The former stage had shorter duration and more daily decomposition quantity; while the latter was opposite. Organic carbon mineralization rates tended to decrease in the order:sandy soil > barren grassland > saline-alkali land > abandoned farmland > artificial forest > cotton > orchard. The rates of organic carbon mineralization were the highest in sandy soils, about (10.36±0.24)%. It indicated that sandy soil had the lowest stability of the soil organic carbon, while carbon sequestration ability of orchard was higher as compared to those of other land use types.Conclusion] Both of SOC mineralization and carbon sequestration ability could be obviously influenced by different land use types.