The potential of river floodplains to emit nitrous oxide (N₂O), a powerful greenhouse gas and ozone-depleting compound, considerably reduces the climate regulation function of these dynamic transition zones between aquatic and terrestrial ecosystems. However, the assessment of N₂O emissions from floodplain soils is challenging, due to the inherently high spatial heterogeneity and the characteristic occurrence of sporadic inundation phases. Such short-term flood events can temporarily alter the conditions for nitrogen (N) transformation processes taking place within distinct microhabitats, which can lead to the local formation of transient hot spots of enhanced N₂O emissions. This situation emphasizes the urgent need to understand how characteristic factors of microhabitat formation in river floodplains control the balance between major microbial N₂O source processes and N₂O reduction to N₂ that determine the magnitude and duration of N₂O emissions. Therefore, the main objective of this thesis project was to systematically assess the relative importance of microhabitat effects related to soil aggregate size, organic matter accumulation, and plant-soil interactions on the microbial N₂O production and consumption processes controlling the spatiotemporal emission patterns of N₂O under changing pore water saturation. To achieve this objective, a mesocosm experiment under controlled climatic conditions, and a study within the framework of a field manipulation experiment were conducted. [...]