三江源区高寒草甸的退化正威胁着区域生态安全,如何恢复其土壤有机碳水平是治理该区域退化高寒草甸的关键.本研究以三江源区典型的退化高寒草甸及经其改建而来的人工草地(3年和7年)为对象,运用酸水解法将土壤有机碳库分为活性碳组分Ⅰ、活性碳组分Ⅱ和惰性碳组分,定量评估人工草地建植后土壤有机碳组分及其生物化学稳定性的变化特征.结果表明:各类样地土壤有机碳组分含量按照惰性碳组分、活性碳组分Ⅰ和活性碳组分Ⅱ的顺序依次递减,表明惰性碳组分是土壤有机碳库的主要构成部分;在建植人工草地3年后,0～30 cm 土层的总有机碳、活性碳组分Ⅰ和惰性碳组分含量均未发生显著变化,而活性碳组分Ⅱ含量出现显著下降(P＜0.05);相比之下,建植人工草地7年后,除土壤活性碳组分Ⅱ含量未发生显著变化外,总有机碳和其他碳组分含量均呈现出增加的变化趋势;退化高寒草甸、建植3年和建植7年人工草地的土壤有机碳惰性指数分别为43.7％～48.4％、42.3％～48.9％和42.3％～53.4％,尽管建植7年人工草地的土壤有机碳惰性指数要高于其他两类样地,但仅在10～20 cm 土层表现为显著差异(P＜0.05).综上表明,长时间的人工植被恢复有助于提升三江源区退化高寒草甸土壤有机碳含量及其生物化学稳定性,促进土壤碳汇功能的恢复.
Abstract
The degradation of alpine meadows in the Three-River Source Region has posed an enormous threat to regional ecological safety.Recovery of soil organic carbon pool is the key to restore degraded alpine meadows.In this study,a degraded alpine meadow(DAM),an artificial grassland established for 3 years(AG3)and an artifi-cial grassland established for 7 years(AG7)in the Three-River Source Region were chosen to quantitatively evalu-ate the changes in fractions and biochemical stability of soil organic carbon after establishing artificial grasslands using acid hydrolysis approach,which divided soil organic carbon pool into labile carbon pool Ⅰ,labile carbon poolⅡ,and recalcitrant carbon pool.The results showed that the contents of soil organic carbon fractions decreased fol-lowing the order:recalcitrant carbon pool＞labile carbon pool Ⅰ＞labile carbon pool Ⅱ at all study sites,suggesting that recalcitrant carbon pool was the main component of soil organic carbon pool.After establishing artificial grass-land for 3 years,the contents of soil total organic carbon,labile carbon pool Ⅰ,and recalcitrant carbon pool did not change,whereas the content of soil labile carbon pool Ⅱ significantly decreased in the 0-30 cm soil layer(P＜0.05).By contrast,establishing artificial grassland for 7 years generally increased the contents of soil total organic carbon and most fractions except for labile carbon pool Ⅱ.The recalcitrant index of soil organic carbon var-ied in ranges of 43.7％-48.4％,42.3％-48.9％and 42.3％-53.4％at DAM,AG3 and AG7,respectively.Although the recalcitrant index of soil organic carbon at AG7 was higher than that at the other two sites,the differ-ence was only significant in the 10-20 cm soil layer(P＜0.05).In conclusion,the findings indicate that long-term artificial vegetation restoration is an effective way to improve the content and biochemical stability of soil organic carbon in degraded alpine meadow of the Three-River Source Region,which would contribute to the recovery of car-bon sink function of soil.
维普
万方数据