15N natural abundance during early and late succession in a middle-European dry acidic grassland
15N natural abundance during early and late succession in a middle-European dry acidic grassland
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DOI：
10.1111/j.1438-8677.2008.00173.x
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发表时间：
2009-09-01
期刊：
影响因子：
3.9
通讯作者：
Werner, C.
中科院分区：
文献类型：
--
作者：
Beyschlag, W.;Hanisch, S.;Werner, C.
分析了德国南部干旱酸性草地两个演替阶段（开放先锋群落和杂草群落）13种植物地上和地下组织的δ N-15和全氮含量，以评价生态位分离的资源利用分配和固氮豆科植物的N-2输入是否是物种共存和演替变化的潜在决定因素。在每个阶段内，植物与不同的豆科植物覆盖的地块进行了比较。土壤无机氮含量，总植物生物量和增量N-15值的散装植物材料显着低于在杂草群落的先驱阶段。观察到的Δ N-15差异是物种特异性而不是位点特异性的。在这两个阶段，也有种特异性的差异，在同位素组成之间的地上和地下植物干物质。种特异性δ N-15特征在理论上可以解释为（i）微生物介导的土壤N转化过程中的同位素分馏;（ii）植物N吸收过程中的同位素分馏或植物-菌根转移过程中的分馏;（iii）植物体内代谢途径和同位素分馏的差异;或（iv）植物群之间有效氮资源（或库）的分配或不同物种对相同资源的差异利用，这似乎是目前情况下最可能的途径。固氮豆科植物对周围植物群落的氮平衡没有显著影响。这是证实了一个独立的原位去除实验的结果，表明3年后，有没有N-2固定豆类地块之间的频率分布没有可测量的差异。
delta N-15 and total nitrogen content of above- and belowground tissues of 13 plant species from two successional stages (open pioneer community and ruderal grass stage) of a dry acidic grassland in Southern Germany were analysed, in order to evaluate whether resource use partitioning by niche separation and N input by N-2-fixing legumes are potential determinants for species coexistence and successional changes. Within each stage, plants from plots with different legume cover were compared. Soil inorganic N content, total plant biomass and delta N-15 values of bulk plant material were significantly lower in the pioneer stage than in the ruderal grass community. The observed delta N-15 differences were rather species- than site-specific. Within both stages, there were also species-specific differences in isotopic composition between above- and belowground plant dry matter. Species-specific delta N-15 signatures may theoretically be explained by (i) isotopic fractionation during microbial-mediated soil N transformations; (ii) isotopic fractionation during plant N uptake or fractionation during plant-mycorrhiza transfer processes; (iii) differences in metabolic pathways and isotopic fractionation within the plant; or (iv) partitioning of available N resources (or pools) among plant groups or differential use of the same resources by different species, which seems to be the most probable route in the present case. A significant influence of N-2-fixing legumes on the N balance of the surrounding plant community was not detectable. This was confirmed by the results of an independent in situ removal experiment, showing that after 3 years there were no measurable differences in the frequency distribution between plots with and without N-2-fixing legumes.