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通过研究黄土丘陵子午岭林区5种典型土地利用类型土壤剖面有机碳分布特征,分析了天然乔木林转变为人工乔木林、天然乔木林转变为农田、天然灌木林转变为农田及撂荒后土壤有机碳变化特征.同时,以浅层(0~100 cm)土壤为对照,探讨了土地利用变化对深层(100~200cm)土壤有机碳储量的影响.结果表明,在0~200 cm剖面上,天然乔木林、天然灌木林、人工乔木林、撂荒地、农田土壤有机碳含量分别为5.85、3.96、4.98、3.09、3.20 g·kg-1,天然乔木林、人工乔木林土壤有机碳含量显著高于天然灌木林、撂荒地和农田(p<0.05).各土地利用类型下浅层和深层土壤有机碳含量分别占0~200 cm土壤有机碳含量的58%~73%和27%~42%,不同土地利用类型间浅层土壤有机碳含量差异显著,但深层土壤有机碳含量差异不大.土地利用变化对土壤有机碳储量影响显著.天然乔木林转变为人工乔木林、天然乔木林转变为农田、天然灌木林转变为撂荒地、天然灌木林转变为农田4种土地利用转变方式0~200 cm土壤有机碳储量分别减少了9.68、52.90、20.20、12.49 t·hm-2,减幅为7%、39%、21%、13%,其中,浅层土壤减少了2%~48%,深层土壤减少了12%~22%.相对于林地开垦为农田而言,农田退耕还林后土壤有机碳的恢复要慢得多.研究结果揭示了浅层和深层土壤有机碳对土地利用变化的敏感性,反映了深层土壤有机碳具有较大的稳定性.
By analyzing the distribution characteristics of soil organic carbon in five typical land use types in the Ziwuling area of Loess Plateau, the change of natural arbor forest into artificial arbor forest, the conversion of natural arbor forest to farmland, the transformation of natural shrub forest into farmland and abandoned farmland Carbon (0 ~ 100 cm) soil as the control, the effects of land use change on soil organic carbon storage in deep soil (100 ~ 200 cm) were discussed.The results showed that in the 0 ~ 200 cm soil profile, natural The content of soil organic carbon in arbor forest, natural shrubbery, artificial arbor forest, wasteland and farmland were 5.85, 3.96, 4.98, 3.09 and 3.20 g · kg-1, respectively. The content of soil organic carbon in natural arbor forest and artificial arbor forest was significantly Natural shrubbery, fallow land and farmland (p <0.05). The contents of soil organic carbon in shallow and deep soil layers accounted for 58% -73% and 27% -42% of soil organic carbon content in 0-200 cm soil layer, There was significant difference in soil organic C between different types of land use, but there was no significant difference in soil organic C between the different land use types. The change of land use had a significant effect on soil organic carbon storage. Natural forest was transformed into artificial forest and natural forest Forest conversion into farmland, natural shrubbery into wasteland, natural shrub forest into farmland 4 kinds of land use change 0-200 cm soil organic carbon storage decreased by 9.68,52.90,20.20,12.49 t · hm-2 Among them, the shallow soil is reduced by 2% -48% and the deep soil is reduced by 12% -22%. Compared with the reclamation of farmland for farmland, the farmland conversion of cropland to forestland The recovery of soil organic carbon was much slower thereafter.The results revealed the sensitivity of shallow and deep soil organic carbon to land use change, reflecting the greater stability of deep soil organic carbon.