Impacts of nitrogen deposition on the forest carbon cycle: from ecosystem manipulations to national scale predictions

氮沉降对森林碳循环的影响：从生态系统操纵到国家规模预测

• 批准号: NE/G004668/1
• 负责人: Peter Levy
• 金额: $ 6.85万
• 依托单位: NERC CEH (Up to 30.11.2019)
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG004668%2F1
• 关键词: Impacts; nitrogen; deposition; forest; carbon

Combustion of fossil fuels and use of fertilisers in agriculture has increased the amount of nitrogen compounds present in the atmosphere and the biosphere. More atmospheric nitrogen is converted into reactive nitrogen by anthropogenic activities than by all natural processes combined. This phenomenal historical increase in nitrogen deposition is responsible for several serious environmental problems, such as soil acidification and nitrogen saturation, nitrate leaching in water courses and eutrophication and changes in the composition of natural ecosystems. In its most extreme forms, it can also cause plant mortality. The added nitrogen also contributes to forming active ozone in the troposphere (where it is damaging) and to producing the greenhouse gases methane and nitrous oxide. To partially counterbalance all these negative effects, nitrogen deposition is also known to increase the sequestration of carbon by forests, which helps to slow down climate change. However, the magnitude of this indirect positive service provided by a pollutant is uncertain, with many estimates suggesting that the effect if rather small. In a previous paper in Nature however, we reported new data showing the effect to be very large for forests of the boreal and temperate regions. This work raised several questions in the community and stimulated a debate which is still ongoing on the real magnitude of this effect. In this project we propose to test whether our findings stand to scientific scrutiny by using two complentary tests: a) an experimental manipulation which artificially elevates the levels of nitrogen deposition over one experimental forest, where we have been measuring carbon sequestration for the past 10 years. Many fertilisation experiments have been carried out in the past, but we contend that they did not realistically simulate the process of nitrogen deposition, as the many ways that nitrogen can interact with the canopy of trees are entirely eliminated when the fertiliser is applied directly on the ground (nitrogen deposition obviously occurs from above the canopy either dissolved in rainfall or as dry deposition over the foliage). b) comparative observations of tree growth across known regional gradients in nitrogen deposition across the UK. Surprisingly few empirical observations have been carried out using this second method, on the assumption that changes in climate, soil fertility, etc. would mask any residual effect due to nitrogen deposition. However, the available literature strongly suggests that high levels of nitrogen deposition have increased tree growth during the 20th century across much of Europe, in support of our theory. Finally, we will use three models to compare our observations against the model predictions. This will also help to determine the mechaism(s) which may promote high rates of carbon sequestration in response to nitrogen deposition.

化石燃料的燃烧和农业中化肥的使用增加了大气和生物圈中存在的氮化合物的数量。人类活动转化为活性氮的大气氮比所有自然过程的总和还要多。氮沉降量的这一惊人的历史增长导致了几个严重的环境问题，如土壤酸化和氮饱和、水道中硝酸盐的淋失和富营养化以及自然生态系统组成的变化。在其最极端的形式下，它还可能导致植物死亡。添加的氮气还有助于在对流层中形成活跃的臭氧(在那里是有害的)，并产生温室气体甲烷和一氧化二氮。为了部分抵消所有这些负面影响，众所周知，氮沉积还会增加森林对碳的固定，这有助于减缓气候变化。然而，污染物提供的这种间接积极服务的规模是不确定的，许多估计表明影响相当小。然而，在之前发表在《自然》杂志上的一篇论文中，我们报告了新的数据，表明这对北方和温带地区的森林产生了非常大的影响。这项工作在社区中引发了几个问题，并引发了一场关于这一影响的真正规模的辩论。在这个项目中，我们建议通过使用两个复杂的测试来测试我们的发现是否经得起科学审查：a)一种实验操作，人为地提高了一片实验森林的氮沉积水平，我们在过去10年里一直在那里测量碳封存。过去已经进行了许多化肥实验，但我们认为它们没有真实地模拟氮沉积的过程，因为当直接在地面上施肥时，氮与树冠相互作用的许多方式都被完全消除了(氮沉积显然发生在树冠上方，要么在降雨中溶解，要么以干沉积的形式出现在树叶上)。B)对英国各地已知的氮沉积区域梯度上的树木生长进行比较观察。令人惊讶的是，使用第二种方法进行的经验观察很少，因为假设气候、土壤肥力等的变化将掩盖由于氮沉积而产生的任何残余影响。然而，现有的文献有力地表明，在20世纪，高水平的氮沉积促进了欧洲大部分地区的树木生长，这支持了我们的理论。最后，我们将使用三个模型将我们的观察结果与模型预测进行比较。这也将有助于确定机制(S)，它可能促进高速率的碳固存对氮沉积的反应。

项目成果

Bulk deposition of organic and inorganic nitrogen in southwest China from 2008 to 2013.

• DOI: 10.1016/j.envpol.2017.04.031
• 发表时间: 2017-08
• 期刊: Environmental pollution
• 影响因子: 8.9
• 作者: Ling Song;F. Kuang;U. Skiba;B. Zhu;Xuejun Liu;P. Levy;A. Dore;D. Fowler

Environmental change impacts on the C- and N-cycle of European forests: a model comparison study

• DOI: 10.5194/bg-10-1751-2013
• 发表时间: 2012-08
• 期刊: Biogeosciences
• 影响因子: 4.9
• 作者: D. Cameron;M. Oijen;C. Werner;K. Butterbach‐Bahl;E. Haas;G. Heuvelink;R. Grote;R. Kiese;M. Kuhnert;J. Kros;A. Leip;G. Reinds;H. Reuter;M. Schelhaas;W. Vries;J. Yeluripati

Selecting Parameters for Bayesian Calibration of a Process-Based Model: A Methodology Based on Canonical Correlation Analysis

• DOI: 10.1137/120891344
• 发表时间: 2013-10
• 期刊: SIAM/ASA J. Uncertain. Quantification
• 作者: F. Minunno;M. Oijen;D. Cameron;J. S. Pereira