高寒草地灌丛化对土壤团聚体稳定性及其胶结物质的影响
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西南民族大学青藏高原研究院

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S154.1

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国家自然科学基金项目(面上项目,重点项目,重大项目)


Effects of shrub-encroached grassland on the stability of soil aggregates and cementing materials in alpine grassland of Qinghai-Tibet Plateau
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Qinghai-Tibet Plateau Research Institute, Southwest Minzu University

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    摘要:

    团聚体是土壤有机碳重要的存储单元,其稳定性直接影响有机碳的固存。为探明草地灌丛化是否影响土壤团聚体稳定性及其胶结物质,本研究以青藏高原东缘4种典型灌丛草地(高山绣线菊、窄叶鲜卑花、小叶锦鸡儿、金露梅)为研究对象,分析土壤团聚体稳定性(>0.25?mm团聚体含量/R0.25、平均重量直径/MWD和分形维数/D)及其胶结物质(团聚体有机碳、铁铝氧化物、钙键和铁铝键结合的有机碳)的含量,结果显示:1)灌丛化降低小叶锦鸡儿样地2~0.25?mm和<0.002?mm团聚体含量和团聚体稳定性(P<0.05),而对其他3种灌丛草地土壤团聚体含量和稳定性影响不显著(P>0.05)。2)灌丛化主要改变小叶锦鸡儿样地和窄叶鲜卑花样地团聚体胶结物质的含量。3)团聚体胶结物质与MWD的增强回归树分析(BRT)的结果显示,高山绣线菊样地中,对团聚体稳定性起主要作用的贡献因子为络合态铁(Fep)无定形态铁铝(Feo、Alo);草地和其他灌丛样地主要贡献因子是团聚体有机碳(SAOC)和游离态铁(Fed)。灌丛化虽增加了小叶锦鸡儿样地<0.053?mm粒径SAOC的含量,但降低了大团聚体和黏粒含量,以及Fed的含量,从而降低了团聚体稳定性,这可能不利于其有机碳的固存。本研究拟为该区域团聚体稳定性理论和有机碳库的动态变化提供理论知识。

    Abstract:

    【Objective】Aggregate is an important storage unit of soil organic carbon, and its stability directly affects the sequestration of organic carbon. The purpose of this study is to investigate whether grassland shrubby affects the stability of soil aggregates and their cementing materials.【Method】Four typical shrubby grasslands (Spiraea alpina、Sibiraea angustata、Caragana microphylla、Potentilla fruticosa) in the eastern margin of the Qinghai-Tibet Plateau were studied, the content of aggregates and their cementing materials (soil aggregate organic carbon, Fe-Al oxides, Ca bond and Fe-Al bond organic carbon) and the stability of aggregates (the content of aggregates >0.25?mm/R0.25、mean weight diameter/MWD and fractal dimension/D) were determined, in order to explore the main contributing factors to the stability of the aggregates under the impact of shrub encroachment. 【Result】 Results show that: 1) Shrub encroachment decreases the aggregate content of 2~0.25?mm and <0.002?mm and aggregate stabilitySin Caragana microphyllaSSplot; However, it has no significant effect on the other three shrub grasslands. 2) Shrub encroachment mainly changes the content of cementing substances in the aggregates of Caragana microphylla plot and Sibiraea angustata plot. 3) The results of boosted regression tree analysis (BRT) between cementing materials and MWD show that the main contribution factors to the stability of aggregates in Spiraea alpina polt are complexed iron (Fep) and amorphous iron and aluminum (Feo, Alo); The major contributors to grassland and other shrub plots are soil aggregate organic carbon (SAOC) and Free iron oxides (Fed). 【Conclusion】 Although shrub encroachment increases the content of SAOC in <0.053?mm, but reduces the content of large aggregates and clay, as well as the content of Fed in Caragana microphylla plot. Thus, the stability of aggregates is reduced, which may be detrimental to the retention of organic carbon. The study intended to provide theoretical knowledge for the stability theory of aggregates and the dynamic change of organic carbon pool in this region.

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陈红,马文明,周青平,邓增卓玛,迪力亚尔,唐思洪,侯晨.高寒草地灌丛化对土壤团聚体稳定性及其胶结物质的影响[J].土壤学报,,[待发表]
Chen Hong, Ma Wenming, Zhou Qingping, Deng Zengzhuoma, Di Liyaer, Tang Sihong, Hou Chen. Effects of shrub-encroached grassland on the stability of soil aggregates and cementing materials in alpine grassland of Qinghai-Tibet Plateau[J]. Acta Pedologica Sinica,,[In Press]

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