The Significance of Nitrogen Uptake and Metabolism by Beech Roots for the Competition for Nitrogen in the Rhizosphere

该项目旨在(1)量化山毛榉根系对无机和有机氮源的吸收，并阐明山毛榉根系与土壤微生物之间对这些氮源的竞争；(2)分析竞争机制；(3)在钙质土壤上以山毛榉为主的氮素有限的落叶森林中，山毛榉自然再生对环境因素的依赖，特别是对干旱的依赖。为此，将在田间条件和温室试验中研究山毛榉和土壤微生物之间竞争的生理原理和模式。在野外，将在凉爽/潮湿（东北方向）和温暖/干燥（西南方向）斜坡之间交换的微观环境中分析水分有效性差异的短期和长期后果。在受控条件下，将量化不同水分水平和不同温度下，山毛榉根与菌根真菌定殖对无机氮和有机氮吸收的意义。这些研究包括测定山毛榉根中NH4+、NO3-和氨基化合物的吸收速率和吸收动力学，并结合N代谢物谱。

This project is aimed (1) to quantify the uptake of inorganic and organic nitrogen sources by beech roots and to elucidate the competition between beech roots and soil microorganisms for these nitrogen sources, (2) to analyse the mechanisms of competition, and (3) to characterise their dependency on environmental factors, particularly on drought, in natural beech regeneration of nitrogen-limited, beech-dominated deciduous forests on calcarious soil. For this purpose, the physiological principles and patterns of competition between beech and soil microorganisms will be studied in experiments under field conditions and in the greenhouse. In the field, short-term and long-term consequences of differences in water availability will be analyzed in microcosms exchanged between a cool/moist (NE aspect) and a warm/dry (SW aspect) slope. Under controlled conditions, the significance of colonisation of beech roots with mycorrhizal fungi for the uptake of inorganic and organic nitrogen will be quantified at different levels of water availability and different temperatures. These studies include the determination of uptake rates and uptake kinetics of NH4+, NO3-, and amino compounds combined with N metabolite profiling in beech roots.