子午岭地区植被演替的土壤碳汇效应

为明确黄土高原地区植被长期恢复的土壤碳汇效应,采用时空互代的方法,研究子午岭地区150年以来8个植被演替序列的土壤有机碳含量及储量的变化特征,分析影响土壤有机碳储量变化的植被因素。结果表明:从农地演替到气候顶级辽东栎(Quercus wutaishanicaMary.)群落,土壤有机碳含量和储量明显增加,表现为演替前期(草本群落)快速增加,后期(乔木群落)趋向稳定的变化特征。剖面上来看,随着土层加深,土壤有机碳含量迅速减少。0—5 cm土层土壤有机碳含量与5—20,20—40 cm土层差异显著(P＜0.05),表明土壤有机碳积累存在明显的表聚效应。枯落物蓄积量与细根生物量均随演替时间呈现出增加的变化特征,前者更有利于提高土壤有机碳储量。0—5 cm土层与0—20 cm土层土壤有机碳储量与演替时间均存在极显著的幂函数关系,不同土层之间土壤有机碳储量线性相关关系显著(P＜0.001)。植被长期演替具有显著的土壤碳汇功能。未来黄土高原地区林、草地的恢复应根据植被带的分异规律,促进自然演替,以进一步提升该地区的土壤碳汇潜能。

Effects on Soil Carbon Sink of Vegetation Succession in the Ziwuling Area

The purpose of this study was to evaluate the soil carbon sink effects of long-term vegetation restoration on the Loess Plateau. A commonly method of spatial and temporal substitution was applied to study the change characteristics of soil organic carbon content and corresponding reserves of eight vegetation succession sequences in the Ziwuling area among nearly 150 years, also analyzed vegetation factors affecting the soil organic carbon reserves changes. The results showed that from slope farmland to Quercus wutaishanica Mary. communities, which was in its highest climatic stage, soil organic carbon contents and corresponding reserves increased significantly, showing a rapid increase in the early stage of succession (grassland communities) and a stable change in the later stage (arbor communities). Soil organic carbon content decreased rapidly as the soil layers deepened in profile. The soil organic carbon content in 0-5 cm soil layer differed significantly from those in 5-20 and 20-40 cm soil layers (P < 0.05), indicating a significant surface aggregation effect of soil organic carbon accumulation. Both litter biomass and fine root biomass were increased with succession time, while litter biomass was more conducive to increasing soil organic carbon reserves. A highly significant power function relationship was found between soil organic carbon reserves and vegetation restoration time for 0-5 and 0-20 cm soil layers, also soil organic carbon storage in different soil layers showed a significant linear correlation (P < 0.001). Long-term vegetation succession had a significant soil carbon sink function. The forests and grasslands restoration in the Loess Plateau should be premised on the distribution patterns of natural vegetation zones and promote its natural succession in the future, thus could further enhance the potential of soil carbon sinks capacity in the region.