人工修复和模拟增温对高寒草地土壤团聚体稳定性及其养分分布的影响

Effects of artificial restoration and simulated warming on soil aggregate stability and nutrient distribution of artificial grassland in alpine grassland area

摘要:

【目的】 探究不同修复方式下气候变暖对高寒草地土壤团聚体稳定性及其养分分布规律的影响。【方法】 在青藏高原高寒草地设置自然恢复（NR）、免耕补播（S）和翻耕补播（TS）3种修复措施， 以重度退化草地（ND）为对照，采用被动式增温法-开顶式气室法（OTC）模拟研究增温对不同修复措施高寒草地土壤团聚体稳定性及养分分布规律的影响。【结果】 修复措施对于各处理大团聚体活性有机碳（LOC）贡献率有显著影响，模拟增温、模拟增温和的修复措施交互作用对各处理大团聚体有机碳 （TOC）有显著影响。NR处理土壤团聚体几何平均直径（GMD）与平均重量直径（MWD）值最高，分别达到了0.76 mm和1.36 mm，显著高于其他处理；TS处理的团聚体质量分数、GMD和MWD最小；增温显著降低了NR处理下大于0.25 mm团聚体含量（R0.25 ）、GMD和MWD。ND处理团聚体中TOC、 全氮（TN）含量最高，NR和TS处理降低了团聚体中TOC、TN含量。【结论】 自然恢复样地有利于提高团聚体的稳定性和活性有机碳富集，但增温过程导致自然恢复样地团聚体稳定性降低，翻耕处理不利于高寒草地土壤团聚体稳定性的提升以及团聚体中养分的固持。

Abstract:

【Objective】 To explore the effects of climate warming on soil aggregate stability and nutrient distribu tion in alpine grassland under different restoration methods.【Method】 Three restoration measures including natural restoration （NR），no-tillage reseeding （ S ） and tillage reseeding （TS） were set up in the alpine grassland of the Qinghai-Tibetan Plateau，and the severely degraded grassland （ND） was used as the control. The effects of warm ing on the stability of soil aggregates and nutrient distribution in alpine grassland with different restoration measures were studied by passive warming-open-top chamber （ OTC ） simulation.【Result】 Remediation measures had a significant effect on the contribution rate of LOC to macroaggregates in each treatment. The interaction of simulated warming，simulated warming and remediation measures had a significant effect on the organic carbon （ TOC ） of mac roaggregates in each treatment. The geometric mean diameter （ GMD ） and mean weight diameter （ MWD ） of soil aggregates in NR treatment were the highest，reaching 0. 76 mm and 1. 36 mm，respectively，which were significantly higher than those in other treatments，and the mass fraction，GMD and MWD of aggregates in TS treatment were the lowest. Warming significantly reduced R0.25 ，GMD and MWD in NR treatment. The contents of TOC and TN in ag gregates were the highest in ND treatment，and the contents of TOC and TN in aggregates were reduced by NR and TS treatments.【Conclusion】 The natural restoration plot is beneficial to improve the stability of aggregates and the enrichment of active organic carbon，but the warming process leads to the decrease of aggregate stability in the natural restoration plot. Tillage treatment is not conducive to the improvement of soil aggregate stability and the fixation of nutrients in aggregates in alpine grassland.