摘要
以鼎湖山马尾松林和季风林2个演替阶段的土壤为研究对象,采用室内恒温(25℃)培养,研究了葡萄糖和不同数量无机氮施入对土壤氨基糖(氨基葡萄糖、氨基半乳糖和胞壁酸)动态的影响,并利用氨基葡萄糖和胞壁酸的比值探讨了真菌和细菌残留物在碳氮固持过程中的相对贡献。结果表明:在整个培养期间,季风林土壤氨基糖总量显著高于马尾松林,尤其在培养初期,增幅远高于马尾松林;在培养后期,马尾松林土壤氨基糖含量下降幅度高于季风林。底物添加对不同微生物来源的氨基糖单体含量的影响也有所差异,以胞壁酸为代表的细菌细胞壁残留物比真菌更易受到外源物质的影响,但真菌细胞壁残留物对土壤有机质的截获和稳定作用大于细菌。真菌、细菌残留物的积累和转化过程可以通过氨基葡萄糖和胞壁酸的比值反映,细菌在培养前期更容易利用外源物质,但随着培养时间的进行,真菌占据了主导地位。不同碳氮比的外源底物对氨基糖总量和各氨基糖单体含量的动态影响不显著。与马尾松林相比,处在演替顶级的季风林土壤易于利用活性底物,显著促进了碳氮的微生物固持和微生物残留物在土壤中的保留,这说明土壤氨基糖作为微生物残留物可以探讨土壤碳氮的耦合机制,对调节土壤碳氮的养分平衡具有重要意义。
Dynamics of three kinds of amino sugars（ glucosamine,galactosamine and muramic acid） in Masson pine and monsoon forest soil in two different stages of succession in Dinghu Mountain,southern China,was amended with glucose and different amounts of inorganic nitrogen in experiment of incubation at a constant temperature of 25 ℃. Relative contribution of microbial communities to carbon and nitrogen immobilization was explored in relation to the ratio of glucosamine to muramic acid. Results showed that during the whole incubation,the total amount of soil amino sugar in the monsoon forest was significantly higher than in the Masson pine forest. At the early period of incubation,the total amount of soil amino sugars increased at a significantly higher rate in the monsoon forest than in the Masson pine forest. With prolonged incubation,the total amount of soil amino sugars decreased to a larger extent in the Masson pine forest than in the monsoon forest. The response of heterogeneous amino sugars was compoundspecific. Muramic acid exclusively originated from bacteria was more easily to be affected by glucose andinorganic N supplies,while fungal cell wall residues such as glucosamine were more stable than those derived from bacteria. The ratio between glucosamine and muramic acid reflects the relative contributions of fungal and bacterial residues in organic matter accumulation and transformation process. The bacteria are more easily available in the early culture of exogenous substance,but as the culture progresses,fungi occupy a dominant position. However,the ratio of carbon to nitrogen in the substrate had no significant effect on the total amount of amino sugars. Compared to the Masson pine forest,utilization of available substrates could significantly stimulate the microbial fixation of carbon and nitrogen in the monsoon forest soil,and thus more microbial residues were produced and accumulated in soil. As a whole,the dynamics of amino sugars is closely associated with the coupling effect of soil carbon and nitrogen,thus playing an important role in regulating supply and requirement of carbon and nitrogen in soil.
出处
《北京林业大学学报》
CAS
CSCD
北大核心
2016年第4期86-93,共8页
Journal of Beijing Forestry University
基金
"973"国家重点基础研究发展计划项目(2011CB403202)
国家自然科学基金项目(41571237)
关键词
氨基糖
活性底物
森林土壤
微生物固持
amino sugar
available substrate
forest soil
microbial immobilization
