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通过对喀斯特山区典型土地利用方式下(灌丛、水田、菜园、玉米地和退耕地)土壤有机碳、团聚体有机碳在不同土壤层次下(0~10、10~20、20~30 cm)含量的系统研究,结合组内-组间主成分分析方法,探讨了喀斯特山区土地利用与团聚体有机碳分布的关系。结果表明:不同土地利用方式下土壤团聚体组成均以大粒径团聚体为主,并且>2 mm粒径团聚体对土壤总有机碳的贡献率可高达70%以上。随土壤层次的增加,土壤有机碳和团聚体有机碳含量降低明显,变幅范围分别为15.1~38.0和15.4~40.3 g·kg-1,表现以水田含量最高,菜园和灌丛相对居中,而以退耕3 a草丛最低。组内-组间主成分分析结果显示,不同土地利用方式下土壤有机碳和团聚体有机碳的累积效应按水田、菜园、灌丛、退耕15 a草丛、玉米地和退耕3 a草丛依次下降,表明水田可作为喀斯特山区土壤有机碳固定的优势农业类型。与玉米地相比,退耕3 a草丛有机碳储量降低了15.8%,而退耕15 a草丛土壤有机碳储量有所提高,但恢复速率相对缓慢,以每年0.35 Mg·hm-2的速度增加。
Soil organic carbon and aggregate organic carbon under different soil layers (0-10, 10-20, 20-30 cm) under typical land use patterns (shrub, paddy field, vegetable garden, cornfield and cropland) Content of the systematic study, combined with intra-group principal component analysis method to explore the Karst mountain land use and the relationship between aggregate carbon emission. The results showed that the aggregates of soil aggregates were dominated by large aggregates under different land use patterns, and the contribution of> 2 mm aggregates to total soil organic carbon was as high as 70%. With the increase of soil layer, the content of organic C in soil organic carbon and aggregate decreased obviously, ranging from 15.1 to 38.0 and 15.4 to 40.3 g · kg-1, respectively, which showed the highest content of paddy field, In order to restore farmland 3 a minimum grass. The results of principal component analysis between groups showed that the cumulative effects of soil organic carbon and aggregate organic carbon under different land use patterns decreased in succession according to paddy field, vegetable garden, shrub, 15 a grassland, cornfield and 3 a grassland, This indicates that paddy field can be used as the predominant agricultural type of soil organic carbon fixation in karst mountainous areas. Compared with maize field, the organic carbon storage of 3 a reduced by 15.8% in grassland, while the soil organic carbon storage in 15 a reduced grassland increased, but the recovery rate was relatively slow, increasing by 0.35 Mg · hm-2 per year.