The stable isotopes 15N and 13C can be used to investigate the nutritional mode of terrestrial orchids and pyroloids (Monotropoideae, Ericaceae). Some of these plants are putatively autotrophic but meet their nitrogen and carbon demands by gaining organic compounds (e.g. amino acids) from mycorrhizal fungi. This so-called partially myco-heterotrophic nutrition is reflected by their isotope signature. The application of a two-source linear mixing model on δ values of such plants allows calculating the percentage of N and C derived from their associated mycorrhizal fungi. Here we present an approach to improve estimates of the plants’ degree of myco-heterotrophy. Due to the presented conversion of δ values into enrichment factors (ϵ), results obtain a better resolution and data from various studies become normalised which facilitates combined representations and meta-analyses. †Revised version of a paper presented at the 30th Annual Meeting of the German Association for Stable Isotope Research (GASIR), 8–10 October 2007, Bayreuth, Germany.

中文翻译：

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一种改进部分真菌异养植物养分增益估计的方法学方法†

稳定同位素 15N 和 13C 可用于研究陆生兰花和吡咯烷酮（Monotropoideae、Ericaceae）的营养模式。这些植物中的一些被认为是自养的，但通过从菌根真菌中获取有机化合物（例如氨基酸）来满足它们对氮和碳的需求。这种所谓的部分真菌异养营养反映在它们的同位素特征上。将双源线性混合模型应用于此类植物的 δ 值，可以计算源自其相关菌根真菌的 N 和 C 的百分比。在这里，我们提出了一种方法来改进对植物异养程度的估计。由于所呈现的 δ 值转换为富集因子 (ϵ)，结果获得更好的分辨率，并且来自各种研究的数据变得标准化，这有助于组合表示和荟萃分析。†在德国稳定同位素研究协会 (GASIR) 第 30 届年会上发表的论文修订版，2007 年 10 月 8-10 日，德国拜罗伊特。