| 森林生态系统对大气氮沉降降低的响应 |
| 摘要点击 1720 全文点击 1347 投稿时间：2022-06-23 修订日期：2022-08-08 |
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| 中文关键词 氮沉降 森林生态系统 氮饱和 酸化 恢复 |
| 英文关键词 nitrogen deposition forest ecosystem nitrogen saturation acidification recovery |
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| 中文摘要 |
| 大气氮沉降是全球变化的重要影响因素之一，而过量氮沉降导致森林出现氮饱和，引起土壤酸化、硝酸根淋溶、氧化亚氮排放增加、植物物种多样性和植被生产力下降.在欧洲、北美和我国大气氮沉降降低的背景下，总结森林生态系统对氮输入降低的响应，不仅能够完善氮沉降对森林生态系统影响的知识体系，也能评估各国已开展的减排行动的成效，为我国制定进一步的减排政策提供科学依据.回顾了欧洲和北美的温带森林以及我国亚热带森林的土壤、地表水、氮循环和植被对大气含氮污染气体和氮沉降降低的响应.土壤溶液中硝酸根浓度对氮沉降的减少响应迅速，但具体响应规律未出现统一趋势.土壤酸化和氮循环过程从高氮沉降中的恢复过程出现滞后现象.森林氮矿化和固持、土壤碳储量和净初级生产力可能需要几十年的时间对氮沉降的减少作出响应.相对而言，虽然有一两年的延迟，土壤无机氮库和氮淋溶量会随着氮沉降的下降而下降.地表水氮浓度与森林生态系统氮状态密切相关.当氮沉降降低时，在历史高氮沉降地区，森林生态系统的氮淋溶下降，因此地表水氮浓度的响应较明显.而在氮缺乏的森林中，普遍较低的地表水氮浓度受到氮沉降变化的影响不显著.地表水酸化的恢复受到土壤硫解吸-矿化和硝化-反硝化影响.叶片氮含量随氮沉降下降而出现降低趋势.我国大气污染物总量控制和随后的"大气污染防治行动计划"的实施，已经带来了西南地区氮饱和亚热带森林和区域地表水从高氮沉降中的恢复. |
| 英文摘要 |
| Nitrogen deposition has serious consequences to global change. Excessive nitrogen deposition leads to nitrogen saturation in forests, resulting in soil acidification, nitrate leaching, an increase in nitrous oxide emissions, and a decrease in plant species diversity and vegetation productivity. Under the reduction of atmospheric nitrogen deposition in Europe, North America, and China, summarizing the response of forests to decreasing nitrogen deposition can not only improve the knowledge framework of the impact of nitrogen deposition on forests, but also evaluate the effects of emission abatement actions, as well as provide scientific basis for future air pollution control. This study reviewed the response of soil, surface water, nitrogen cycle, and vegetation of temperate forests in Europe and North America and subtropical forests in southwest China to the reduction in atmospheric nitrogen pollution gases and thus nitrogen deposition. The soil water nitrogen concentration responded rapidly to the nitrogen deposition reduction, although the trend was inconsistent. The soil acidification and nitrogen cycles showed a delayed response of recovery from high nitrogen deposition. The nitrogen mineralization and immobilization, soil carbon retention, and net primary production might take decades to respond to the nitrogen deposition reduction. However, the soil inorganic nitrogen pool and nitrogen leaching decreased with the decline in nitrogen deposition, although a one-or two-year lag existed. The surface water nitrogen concentration was closely related to nitrogen status in forests. After the nitrogen deposition decreased, the nitrogen leaching and thus the surface water nitrogen concentration decreased in the areas with historically high nitrogen deposition. However, the low surface water nitrogen concentration in the nitrogen-limited forests was not significantly affected by the nitrogen deposition changes. The recovery of surface water acidification was affected by soil sulfur desorption/mineralization and nitrification/denitrification. The foliar nitrogen concentration decreased with the decline in nitrogen deposition. The nitrogen-saturated forests and regional surface water in southwest China showed a recovery trend from high nitrogen deposition, as a consequence of the implementation of the Total Emissions Control of Air Pollutants and later the Action Plan of Air Pollution Prevention and Control. |
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