喀斯特峰丛洼地原生林土壤团聚体有机碳的剖面分布

以喀斯特峰丛洼地的伊桐、侧柏和菜豆树3个原生林植物群落为对象,分析了土壤团聚体的组成、有机碳及其剖面分布.结果表明:3个植物群落的土壤分布均以＞2 mm大粒径团聚体为主,约占土壤团聚体总量的76％.土壤总有机碳含量介于12.73 ～ 68.66 g·kg-1之间,群落类型显著影响土壤有机碳含量及其分布.＜1 mm小粒径团聚体中的有机碳含量比＞2 mm团聚体稍高,但大部分土壤有机碳储存在大粒径团聚体中,＞2 mm团聚体对土壤有机碳的贡献率约70％.2 ～5和5～8 mm团聚体含量与土壤有机碳含量呈显著正相关.提高土壤中2～8 mm团聚体的含量能有效增强喀斯特地区土壤固碳能力.伊桐群落2～8 mm土壤团聚体的含量及其全土有机碳含量分别达46％和37.62 g· kg-1,伊桐更适合作为喀斯特地区生态恢复树种.

Profile distribution of soil aggregates organic carbon in primary forests in Karst cluster-peak depression region

Soil profiles were collected from three primary forests (Itoa orientalis, Platycladus orientalis, and Radermachera sinica) in Karst cluster-peak depression region to study the composition of soil aggregates, their organic carbon contents, and the profile distribution of the organic carbon. In the three forests, >2 mm soil aggregates were dominant, occupying about 76% of the total. The content of soil total organic carbon ranged from 12.73 to 68.66 g x kg(-1), with a significant difference among the forests. The organic carbon content in <1 mm soil aggregates was slightly higher than that in >2 mm soil aggregates, but most of soil organic carbon was stored in the soil aggregates with greater particle sizes. About 70% of soil organic carbon came from >2 mm soil aggregates. There was a significant positive relationship between the contents of 2-5 and 5-8 mm soil aggregates and the content of soil organic carbon. To increase the contents of 2-8 mm soil aggregates could effectively improve the soil carbon sequestration in Karst region. In Itoa orientalis forest, 2-8 mm soil aggregates accounted for 46% of the total, and the content of soil total organic carbon reached to 37.62 g x kg(-1), which implied that Itoa orientalis could be the suitable tree species for the ecological restoration in Karst region.