Högberg Peter
Department of Forest Site Research, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden.
New Phytol. 1990 Jul;115(3):483-486. doi: 10.1111/j.1469-8137.1990.tb00474.x.
The partial contribution by fixed nitrogen in N -fixing plants can be estimated if the N natural abundance of non-N -fixing reference species, which derive their N from the soil, deviates from that of atmospheric N (the N natural abundance method). Data from Tanzanian miombo woodland showed a significant difference (= 1.0-2.5 δ N% ) in N abundance between ectomycorrhizal and vesicular-arbuscular (VA) mycorrhizal reference species. This finding casts doubt upon arbitrary selection of reference species, and also raises the possibility of using N abundance as a marker of the ectomycorrhizal habit. It is suggested that the higher N abundance of ectomycorrhizal tree species could result from differences in discrimination during uptake or from greater utilization of organic N.
如果从土壤中获取氮的非固氮参考物种的氮自然丰度与大气氮的氮自然丰度存在偏差（氮自然丰度法），那么就可以估算出固氮植物中固定氮的部分贡献。来自坦桑尼亚miombo林地的数据显示，外生菌根参考物种和泡囊-丛枝（VA）菌根参考物种之间的氮丰度存在显著差异（=1.0 - 2.5 δN%）。这一发现对参考物种的任意选择提出了质疑，同时也增加了将氮丰度用作外生菌根习性标志物的可能性。有人认为，外生菌根树种较高的氮丰度可能是由于吸收过程中歧视性的差异，或者是由于对有机氮的利用率更高。
