Nitrogen saturation of forested catchments in central Japan - Progress or recovery?
Nitrogen saturation of forested catchments in central Japan - Progress or recovery?
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DOI：
10.1080/00380768.2021.1991228
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发表时间：
2021-10
影响因子：
2
通讯作者：
H. Sase;Masamichi Takahashi;K. Matsuda;N. Yamashita;U. Tsunogai;F. Nakagawa;M. Morohashi;Hiroki Yotsuyanagi;T. Ohizumi;Keiichi Sato;J. Kurokawa;M. Nakata
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文献类型：
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作者：
H. Sase;Masamichi Takahashi;K. Matsuda;N. Yamashita;U. Tsunogai;F. Nakagawa;M. Morohashi;Hiroki Yotsuyanagi;T. Ohizumi;Keiichi Sato;J. Kurokawa;M. Nakata
摘要 大气中活性氮（Nr）的过量输入会对森林生态系统造成干扰，包括土壤和溪水酸化、植物养分失衡、物种组成改变（如生物多样性丧失）以及氮（N）淋溶到溪水中。自20世纪50年代以来，日本中部（或中部地区）经历了国内和跨界空气污染。中国的氮氧化物排放量在2011/2012年达到峰值，尽管氨排放峰值尚未确定。这些排放的变化已逐渐反映在日本中部大气氮沉降速率和生态系统的生物地球化学循环中。我们根据近期发表的文献和最新可用数据集，综合分析了日本中部森林生态系统当前的氮饱和状况。岐阜县太平洋沿岸的伊自良湖流域（IJR）的溪水在20世纪90年代中期酸化且氮饱和，但自21世纪00年代中期以来，随着硝酸盐（NO3 -）浓度的降低已开始恢复。氮饱和的进展和恢复似乎与大气沉降趋势、气候异常（如1993/1994年夏季凉爽干旱）以及森林管理有关。新潟县日本海沿岸的梶川森林流域（KJK）内溪水中的NO3 -浓度持续增加，尽管由于大气硫（可能还有氮）沉降的减少，该流域似乎正在从酸化中恢复。最后，KJK溪水中的NO3 -浓度变得高于IJR，这与21世纪初的情况正好相反。最近对NO3 -中17O过剩的分析估计，通过溪水输出的未经生物处理的大气NO3 -在KJK比在IJR更多。在大气氮过量输入（仍超过10千克/公顷·年）的情况下，土壤 - 植物系统中的氮循环可能无法如预期那样发挥作用，尤其是在KJK。除了大气氮沉降外，随着针叶林的成熟氮吸收速率降低，以及降水量/降水模式的变化似乎加速了日本中部森林流域的氮淋溶。
ABSTRACT Excess inputs of reactive nitrogen (Nr) from the atmosphere will cause disturbances to forest ecosystems, including soil and stream water acidification, plant nutrient imbalances, alterations of species compositions (such as biodiversity losses), and nitrogen (N) leaching into stream water. Central Japan (or Chubu region) has experienced both domestic and transboundary air pollution since the 1950s. Emissions of nitrogen oxides in China peaked in 2011/2012, although the peak of ammonia emissions has not been confirmed. Changes in these emissions have been reflected gradually in atmospheric N deposition rates and the biogeochemical cycle in ecosystems in central Japan. We synthetically analyzed the current N saturation situation for forest ecosystems in central Japan based on our recent publications and the latest available dataset. The stream water in the Lake Ijira catchment (IJR) on the Pacific side in Gifu Prefecture became acidified and N-saturated in the mid-1990s but has begun to recover with a decrease in nitrate (NO3 –) concentration since the mid-2000s. The progress and recovery of N saturation appeared to be related to the trends of atmospheric deposition, climatic anomalies (such as the cool and drought summers in 1993/1994), and forest management. The NO3 – concentrations in stream water within the forest catchment of Kajikawa (KJK) on the Sea of Japan side in Niigata Prefecture have continued to increase, although the catchment seems to be recovering from acidification owing to a decline in atmospheric sulfur (and probably N) deposition. Finally, the NO3 – concentration in stream water in KJK became higher than that in IJR, a direct inversion of the situation in the early 2000s. The recent analysis of 17O excess in NO3 – estimated that the export of biologically unprocessed atmospheric NO3 – via stream water was larger in KJK than in IJR. The N cycle in soil-plant systems likely does not function as expected under excess atmospheric N input (still over 10 kg ha–1 year–1), especially in KJK. In addition to atmospheric N deposition, reduced N uptake rates as coniferous forests mature, and changing precipitation amounts/patterns appear to accelerate N leaching from forest catchments in central Japan.