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以西南喀斯特山区几种典型土地利用方式为对象,研究了土地利用及退耕对全土、团聚体活性有机碳及其恢复能力的影响.结果表明,随土壤深度的增加,土壤活性有机碳含量及其离散程度呈下降趋势,其中0~10 cm土壤活性有机碳含量与10~20 cm和20~30 cm两个剖面层次达极显著(P<0.01)差异水平;活性有机碳含量在0~10 cm范围内以<0.25 mm团聚体粒径最高,然而在10~20 cm和20~30 cm活性有机碳在各粒径中的分布并不明显;不同土地利用方式下,水田中无论全土还是团聚体中活性有机碳均表现出较高水平,灌从次之,而以退耕3 a草丛最低.组内-组间主成分分析表明,土地利用方式与土壤活性有机碳的累积特征表现为水田>灌丛>退耕15 a草丛≈旱地>退耕3 a草丛,其中退耕15 a草丛在0~10 cm深度下较旱地增加了20.3%,且达到灌丛土壤活性有机碳的80%,表明喀斯特山区土地退耕初期土壤有机碳恢复速度相对缓慢,而随退耕时间的推移,土壤碳汇效应逐步显现.
The effects of land use and returning farmland to the active organic carbon and its restoration ability of total soil and aggregate were studied using several typical land use patterns in the Karst mountain area of Southwest China. The results showed that with the increase of soil depth, the content of active soil organic carbon and its (P <0.01). The contents of active organic carbon (C = 0-10 cm) in 0-10 cm soil layer were significantly different from those in 10-20 cm and 20-30 cm sections Within the range of <0.25 mm, the aggregate size was the highest, however, the distributions of active organic carbon in 10-20 cm and 20-30 cm were not obvious in each particle size. Under different land use types, both the soil and the aggregates The active organic carbon showed the highest level, followed by the irrigation, and lowest in the grassland 3. The principal component analysis between the two groups showed that the cumulative characteristics of land use and soil active organic carbon were paddy fields> The results showed that the grassland 15 a was grass ≈ dry land> grass retired 3 a, of which the grassland 15 a was 20.3% more than the dry land at 0-10 cm depth and reached 80% of the soil active organic carbon in the shrub soil, Early recovery of soil organic carbon Relatively slow, but with the passage of time farmland, the soil carbon sink effect gradually.