高寒草甸土壤可溶性有机氮及其季节动态研究

发布时间：2018-05-14 06:50

本文选题：高寒草甸 + 可溶性有机氮　；参考：《兰州大学》2015年硕士论文

【摘要】：土壤可溶性有机氮(Soluble Organic Nitrogen, SON)是陆地生态系统氮素的重要组成部分,因其具有较强的流动性与养分的有效性,在植物和微生物吸收利用、氮素矿化、淋溶和流失等方面都扮演着重要的角色。目前国际上对土壤SON的含量、组成及其季节动态的研究较少,而现有的SON研究又主要集中在温带森林生态系统,对高寒草甸土壤SON的报道非常有限。本文分别以甘南玛曲高寒草甸中以珠芽蓼(Polygonum viviparum L.)、禾叶嵩(Kobresia graminifolia C. B. Clarke)和垂穗披碱草(Elymus nutans Griseb.)为优势植物的土壤为研究对象,对其SON含量、组成及其季节动态进行定性和定量研究,为高寒草甸植物利用有机氮的机制提供科学依据,并为阐述SON的生态意义提供理论基础。主要研究结果如下：1.高寒草甸三种植物土壤浸提液中的SON含量范围在279.35-882.77 mg/kg,占土壤总可溶性氮库中占94.1%-99.9%,占土壤总氮库的5.2%-20.0%。三种植物土壤SON含量均高于同期无机氮含量20倍,差异极显著(p0.01)。三种植物土壤的SON含量均表现为夏季秋季春季,三种植物间无显著差异。SON的含量主要受到土壤性质、植被类型、土壤微生物、气候等多种因素的综合影响。2.三种植物土壤中SON的组成不同,其中疏水、亲水组分所占比例与土壤浸提方式密切相关。禾叶嵩和垂穗披碱草土壤的KCl浸提液中,SON所含的疏水物质所占比例较大,而在蒸馏水(H20)浸提液中所得结果相反。珠芽蓼土壤两种浸提液得到的SON中,亲水、疏水组分所占比例相当。结果表明,使用盐溶液浸提土壤比使用水溶液浸提更有助于疏水组分的提取。3.三种植物土壤中,总氨基酸含量皆表现为夏季秋季春季；禾叶嵩土壤的总氨基酸含量最高,占SON的比例最大。垂穗披碱草土壤氨基酸含量与无机氮的比值最高为1：4。总氨基酸在SON中所占比例很小,可能与其在土壤中周转迅速、积累少有关。本项研究得到以下结论：在高寒草甸自然生态系统中,土壤氮储量丰富,土壤中SON库的大小远超过无机氮库,并且氨基酸在SON库中占有一定比例,意味着一些小分子的SON有可能被植物直接吸收利用,并且SON在该生态系统氮循环中可能占有重要地位。SON的组成主要与其来源有关；影响SON含量的因素包括生物、非生物因素,其中土壤性质、植被类型以及真菌在土壤微生物群落中的比例对SON的影响可能在高寒草甸生态系统中占主导作用。
[Abstract]:Soluble organic nitrogen (Soluble Organic Nitrogen, SON) is an important component of nitrogen in terrestrial ecosystems. Because of its strong fluidity and nutrient availability, it is absorbed and utilized by plants and microbes, and nitrogen mineralization occurs in terrestrial ecosystems. Leaching and loss play an important role. At present, there are few studies on the content, composition and seasonal dynamics of soil SON in the world, while the existing studies of SON mainly focus on temperate forest ecosystems, and the reports on soil SON in alpine meadow are very limited. In this paper, Polygonum viviparum L., Kobresia graminifolia C. B. Clarke) and Elimus nutans Griseb.were used in the alpine meadow of Maqu, Gannan, respectively. The content, composition and seasonal dynamics of SON were studied qualitatively and quantitatively in order to provide scientific basis for the mechanism of utilization of organic nitrogen by alpine meadow plants, and to provide a theoretical basis for expounding the ecological significance of SON. The main results are as follows: 1. The content of SON in the extracts of three plant soils in alpine meadow ranged from 279.35-882.77 mg / kg, accounting for 94.1-99.9% of the total soluble nitrogen pool and 5.2-20.0% of the total nitrogen pool. The SON content of three plant soils was 20 times higher than that of inorganic nitrogen in the same period, and the difference was significant (p0.01). The SON contents of the three plant soils were all in summer, autumn and spring. There was no significant difference between the three plants. The content of son was mainly affected by soil properties, vegetation types, soil microbes, climate and other factors. The composition of SON in the three plant soils was different, among which the proportion of hydrophobic and hydrophilic components was closely related to the soil extraction methods. The hydrophobic substances of son in the KCl extractions of Kobresia humilis and Elaeagnus pericarpa were higher than those in the distilled water (H20). The proportion of hydrophilic and hydrophobic components of SON obtained from two kinds of soil extracts of Polygonum hydrophylla was equal. The results showed that the extraction of hydrophobic components by salt solution was more helpful than that by aqueous solution extraction. The content of total amino acids in three plant soils was summer, autumn and spring, while the content of total amino acids in Kobresia humilis soil was the highest, accounting for the largest proportion of SON. The ratio of amino acid content to inorganic nitrogen in soil was 1: 4. The small proportion of total amino acids in SON may be related to its rapid turnover and low accumulation in soil. The results of this study are as follows: in the natural ecosystem of alpine meadow, soil nitrogen reserves are abundant, the size of SON pool in soil is much larger than that of inorganic nitrogen pool, and amino acids account for a certain proportion in SON pool. This means that the SON of some small molecules may be absorbed directly by plants, and that the composition of SON may play an important role in the nitrogen cycle of the ecosystem. The composition of son is mainly related to its source; the factors affecting the content of SON include biological and abiotic factors. The effects of soil properties, vegetation types and the proportion of fungi in soil microbial communities on SON may play a dominant role in alpine meadow ecosystems.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S812.2

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