| 黄土高原植物与不同粒级中土壤体系氮同位素组成变化及意义 |
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| 引用本文：王政,刘卫国.2005.黄土高原植物与不同粒级中土壤体系氮同位素组成变化及意义[J].地球学报,26(z1):-235. |
| DOI：10.3975/cagsb.2005.s1.77 |
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| 中文摘要:目前观点认为，自然生态条件下的非固氮植物-土壤体系中，根据分解供给是土壤中氮的主要来源。研究植物-土壤体系中氮素的分布转化规律是评估土壤中氮素有效性的重要基础。笔者选取黄土高原这一典型西北生境中植物-土壤样品，通过测定样品氮含量与同位素自然丰度组成变化，来说明不同粒级土壤中氮素的分解水平与潜力。
结果表明，植物在分解过程中氮同位素产生3‰-5‰不等的分馏，在粒级由大到小变化的土壤组份中，随着可分解氮素的减少，土壤总氮同位素比值表现不同程度的偏正趋势，并于小粒级中趋于稳定，这与含量测量中表现出的矿化氮含量增加规律一致。氮的同位素自然丰度组成对于植物分解程度的灵敏响应，使其可以作为一种指示植物-土壤体系中氮素转化程度与趋势以及评估土壤中氮的有效性的指标，应用于自然生态研究。 |
| 中文关键词:氮同位素 植物-土壤粒级 氮分解潜力 |
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| Implications of Stable Nitrogen Isotopic Compositional Variation of Plant and Soil with Different Size Fractions in Loess Plateau |
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| Abstract:The plant-soil system is an important pool of global nitrogen cycle. Based on a study of nitrogen transformation, this paper has evaluated introgen availability in soil. Many experts consider that the major source of soil nitrogen in natural ecological conditions depends on the decomposition degree of underground portions of plant roots. The authors investigated several plant-soil samples with different size fractions in a typical ecological environment of loess plateau and measured contents of total nitrogen (TN), mineral ni-trogen and δ15N values in the samples. Studies show that δ15N fractionation from 3‰ to 5‰ results most likely from plant decomposi-tion in solil of different size fractions. With the decrease of fraction size,δ15N cotnuously increases, and the values tend to be stable in the smalest fraction, decomposable nitrogen becomes infrequent in soil and contents of mineral nitrogen increase distinctly. Such a regularity indicates that nitrogen isotope abundance could serve as a sensitive indicator in evaluating the plant decomposition degree and the total nitrogen level and potential in soil. Further studies are recommended such as the diversities of δ15N values between NH+4 - N and NO3- - N in different size fractions of soil. |
| keywords:nitrogen isotope plant-soil size fraction nitrogen decomposition level |
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