喀斯特峰丛洼地次生林土壤有机碳的剖面分布特征

采用样方法研究了喀斯特峰丛洼地八角枫(Alangium chinensis)、盐肤木(Rhus chinensis)、黄荆(Vitex negundo) 3种典型次生林群落土壤有机碳（SOC）含量、密度的剖面分布特征。结果表明，土壤有机碳含量与土壤根系生物量呈极显著正相关；不同次生林群落060 cm土壤有机碳平均含量和密度不同，依次为黄荆八角枫盐肤木，盐肤木的碳含量显著低于黄荆和八角枫群落，碳密度显著低于黄荆；3种次生林群落土壤碳含量和密度都与土壤深度有较好的线性关系，随土壤深度的增加而降低，2060 cm各层次的差异不显著，但均显著低于010 cm土层；不同次生林群落土壤各层次碳含量和密度均表现为为黄荆八角枫盐肤木，其中盐肤木群落1040 cm 3个层次的碳含量及2030 cm的碳密度显著低于另外2个群落。由此可见，喀斯特峰丛洼地退化生态系统合理的植被恢复方式是促进该区域生态重建和碳贮存的关键。

Profile distribution characteristics of soil organic carbon in secondary forests in depressions between Karst hills

The profile distribution characteristics of soil organic carbon(SOC) content and density in three secondary forests communities(Alangium chinensis,Rhus chinensis and Vitex negund) in depressions between Karst hills in southwest China were investigated.The results show that there are significant correlations(P<0.01) between soil organic carbon contents and root contents in the three communities.The average soil organic carbon contents and densities are different in the layers from 0-10 cm to 50-60 cm of the three communities,and both of them are in the order of Vitex negundo > Alangium chinensis > Rhus chinensis.Soil organic carbon contents and densities in the three forest types are decreased with the increase of soil depth,and there is a good liner relationship between them.The maxima of soil organic carbon and density are likely in 0-10 cm soil surface layer.The significant or highly significant differences are found in both soil organic carbon contents and densities between 0-10 cm soil layer and other layers in the same forest community,while no significant differences are found among other layers.Soil organic carbon contents and densities are in the order of Vitex negundo > Alangium chinensis > Rhus chinensis communities in the same soil layers of different forest communities.The soil organic contents of 10-40 cm soil layers and soil organic carbon densities of 20-30 cm soil layers of Rhus chinensis community are significantly lower than those of the other two communities.Therefore,reasonable vegetation restoration plays a key role in improving regional ecological reconstruction and carbon storage in degraded ecosystems in depressions between Karst hills in southwest China.