Competitive patterns of N partitioning between plants and microorganisms in intact plant-soil-systems

我们对生态系统氮循环过程的认识在很大程度上被忽视了植物与微生物的相互作用和对氮的竞争，以及地下氮通量在空间和时间上的巨大变异性所伪造。为了阐明山毛榉与微生物之间氮分配的竞争模式及其对环境条件变化的响应，将在植物-土壤系统中进行田间试验、溶渗仪和微观研究，以追踪稳定同位素（15N, 13C）。微型溶菌仪中的三重标记方法（15N/13C谷氨酰胺，15NH4 +, 15NO3 -）与15N示踪模型相结合，将允许同时模拟完整植物-土壤系统中的主要N通量，从而以面向过程的方式表征植物-微生物竞争。此外，将直接测量完整土壤岩心的N2和N2O排放，以量化反硝化在NO3 -竞争中的作用。近红外光谱（NIRS）将用于高分辨率测量氮竞争指标，以克服氮通量的高时空变化和氮分配的竞争模式。

Our knowledge on ecosystem N cycling processes is largely falsified by the disregard of plant-microbe interactions and -competition for N, and by the enormous variability of belowground N fluxes in space and time. To elucidate competitive patterns of N partitioning between beech and microorganisms and its responses to changing environmental conditions, stable isotopes (15N, 13C) will be followed in field experiments, lysimeter and microcosm studies through the plant-soil system. Triple labelling approaches (15N/13C glutamin, 15NH4 +, 15NO3 -) in mini-lysimeters in combination with 15N tracing modelling will allow to simultaneously mimic major N fluxes in intact plant-soil systems, and thus, to characterize plant-microbe competition in a process-oriented way. Furthermore, N2 and N2O emissions from intact soil cores will be measured directly in order to quantify the role of denitrification in the competition for NO3 - . Near infrared spectroscopy (NIRS) will be used to measure indicators of competition for N with high resolution in order to overcome the high temporal and spatial variation of N fluxes and competitive patterns of N partitioning.