子午岭林区不同植被恢复阶段土壤有机碳变化研究

Changes of Soil Organic Carbon in Various Stages of Vegetation Restoration in Ziwuling Mountain

研究了子午岭林区植被恢复过程中土壤有机碳含量、团聚体有机碳分布以及不同粒级团聚体有机碳对土壤有机碳的贡献率。研究结果表明,0—100 cm剖面上有机碳含量加权平均值随植被恢复年限逐渐升高,坡耕地0—100 cm土层土壤有机碳加权平均值为3.54 g/kg,弃耕地、草地、灌木和乔木阶段分别比坡耕地提高6.8%,36.6%,41.5%和73.6%;0—20 cm土层土壤有机碳含量随植被恢复的提高幅度明显高于20 cm以下土层;0—5和5—10 cm土层土壤各粒级团聚体有机碳含量随植被恢复年限逐渐增加,并有向大粒级(>2 mm)团聚体中富集的趋势,10—20 cm土层土壤团聚体有机碳含量随植被恢复变化不明显;弃耕地、草地、灌木和乔木阶段0—20 cm土层>5,5～2和2～1 mm粒级团聚体有机碳贡献率高于坡耕地,说明植被恢复0—20 cm土层土壤增加的有机碳更多地固定在>1 mm粒级团聚体中。

The soil organic carbon（SOC） contents,distribution of organic carbon in soil aggregates,and organic carbon contribution rates of variously sized soil aggregates were studied during vegetation restoration in Ziwuling Mountain.The results show that the weighted mean of SOC was 3.54 g/kg for the 0—100 cm soil profile of sloped cropland,while the weighted means of SOC of 0—100 cm soil profiles of abandoned land,grassland,shrub and arbor phases were 6.8%,36.6%,41.5% and 73.6%,respectively,higher than that of slop cropland.The increasing magnitudes of SOC contents of 0—20 cm soil layer were higher than those of soil layers below following vegetation restoration.The SOC contents of aggregates of all sizes in the 0—5 and 5—10 cm soil layers increased gradually and the SOC enriched in the macro-aggregates（2 mm） over time along with vegetation restoration.No clear change of SOC contents in the 10—20 cm soil layer for aggregates of all sizes.The SOC contribution rates of 5,5～2 and 2～1 mm aggregates in 0—20 cm soil layer of abandoned land,grassland,shrub and arbor were higher than that of sloped cropland,indicating that the increased part of SOC in 0—20 cm soil layer were stored mainly in 1 mm aggregates during vegetation restoration.