云雾山草原区不同植被恢复阶段土壤团聚体活性有机碳分布特征

以宁夏云雾山草原自然保护区不同植被群落为研究对象,对0～20 cm土层土壤团聚体活性有机碳分布特征进行分析.结果表明:(1)不同植被群落土壤团聚体活性有机碳含量顺序为退耕草地<百里香群落<铁杆蒿群落<大针茅群落<长芒草群落,与退耕草地相比,封育草地各粒径团聚体活性有机碳含量均显著提高 (P<0.05),表明随着植被的恢复土壤团聚体活性有机碳含量提高并趋于稳定,土壤碳汇效应有可能增强.(2)植被恢复主要影响大团聚体(>0.25 mm)中活性有机碳含量,其中0.5～0.25 mm粒径团聚体中活性有机碳含量最高,微团聚体(<0.25 mm)中活性有机碳含量最低.(3)植被恢复前期(退耕草地-铁杆蒿群落)0～10 cm土层>0.5 mm粒径团聚体中活性有机碳含量较10～20 cm土层有所增加,<0.5 mm粒径团聚体活性有机碳含量变化不大,恢复至后期到长芒草阶段时,0～10 cm土层<0.5 mm粒径团聚体中活性有机碳含量也开始提高, 各粒径0～10 cm土层团聚体活性有机碳含量均比10～20 cm土层有所提高.(4)相关性分析表明,土壤团聚体活性有机碳含量与土壤团聚体总有机碳含量呈极显著线性正相关关系(r=0.9394),团聚体活性有机碳含量可以作为衡量土壤团聚体有机碳动态的一个敏感性指标.

Distribution Characteristics of labile organic carbon in soil aggregates in different stages of vegetation restoration of grassland in Yunwu Mountain

Labile organic carbon (LOC) in soil aggregetes plays an important role in carbon fixation. We analized content of labile organic carbon(LOC) in soil aggregates from 0 to 20 cm during vegetation restoration in Yunwu Mountain. The results showed that:(1) content of LOC in soil aggregates followed the order of abandoned grassland 0.25 mm). Furthermore, Content of LOC in fraction of 0.5-0.25 mm was higher than other size fraction and the content was lowest in micro-aggregate (<0.25 mm). (3)The effecs of soil depths on content of LOC in soil aggregetes was different. Content of LOC in depth of 0-10 cm in size of >0.5 mm was higher than the depth of 10-20 cm in prophase of vegetation restoration (abandoned grassland-Artemisia gmelinit community ) while content of LOC in size of <0.5 mm showed similar community in the late of vegetation restoration (Stipa bungeana community ). (4)The linearly positive correlation was found between content of LOC and total organic carbon in soil aggregates. The correlation coefficient reached 0.9493 which was extreamly significant. This showed that content of labila organic carbon in soil aggregates could be a sensitive index to indicate dynamic of soil organic carbon.