Spatio‐temporal variability and intra‐event variation of throughfall ammonium and nitrate in a pine plantation

作者：Chunyu Wang, Xinchao Sun, Chunbin Fan, Yixin Wei, Guangkai Jia, Yanhong Cao · 发表于：Hydrological Processes · 年份：2023 · DOI：10.1002/hyp.14872 · 被引用次数：12 · 研究领域：Plant Water Relations and Carbon Dynamics、Plant responses to elevated CO2、Atmospheric chemistry and aerosols

Abstract Forest canopies are the functional interface between ecosystem and the atmospheric nitrogen (N) deposition. However, the sources of spatio‐temporal variability and intra‐event variation of N deposition via throughfall ( TF ) remain ambiguous. Here, we analysed TF samples for concentrations and fluxes of ammonium (NH 4 + ) and nitrate (NO 3 − ) using an array of 20 fixed‐position collectors on an event and within event basis throughout the 2019 growing season in a Chinese pine plantation, Northern China. Results showed that the volume weighted mean concentrations of NH 4 + and NO 3 − in TF were significantly higher than those in bulk precipitation ( BP ) during the study period. A canopy budget model indicated that canopy uptake was more dominant than dry deposition for NH 4 + , while the reverse was true for NO 3 − . This caused a comparable TF NH 4 + flux but an enhanced TF NO 3 − fluxes compared to BP . The intra‐event trend and magnitude of TF NH 4 + and NO 3 − concentrations were influenced by the antecedent dry period and rainfall intensity, and indicated that biological nitrification may occur in the canopies. In addition, due to the larger of canopy NH 4 + uptake that counteracted the amplifying effect of dry deposition, the spatial variability of TF NH 4 + concentration was significantly lower than that of TF NO 3 − concentration, and exhibited more temporal persistence. No relationship was found between the spatial distribution of TF NH 4 + concentration and...