15N foliar dilution of lodgepole pine: from where does the atmospheric N originate

土壤微生物是森林生态系统的重要组成部分，在养分循环、土壤结构维持和植物生长调节中发挥着重要作用。尽管氮循环在全世界的森林中发挥着至关重要的作用，但即使是对森林生长至关重要的氮循环过程也尚未完全阐明。例如，黑松是一种广泛分布的物种，已知在各种土壤条件下生长。它在营养贫乏、质地粗糙的土壤上生长的能力对于一个不知道固氮的物种来说是独一无二的，并提出了关于其在这种环境中的氮源的有趣问题。我建议确定固氮细菌是否能够固定氮，而生活在松树的菌根，根，茎和针叶组织内使用生物标志物可视化细菌以及nif基因表达原位。

Soil microorganisms are integral components of forest ecosystems, fulfilling critical roles in nutrient cycling, maintenance of soil structure, and regulation of plant growth. A process even as central to forest growth as nitrogen cycling has yet to be fully elucidated, notwithstanding the vital role it plays in forests worldwide. For example, lodgepole pine is a widely distributed species known to grow under a variety of soil conditions. Its ability to grow on nutrient-poor, coarse-textured soils is unique for a species not known to fix nitrogen, and poses interesting questions regarding its nitrogen source in such environments. I propose to determine if nitrogen fixing bacteria are capable of fixing nitrogen while living inside pine mycorrhiza, root, stem and needle tissues using biomarkers to visualize bacteria as well as nif gene expression in situ.