Are tropical uplands regional hotspots for methane and nitrous oxide?

热带高地是甲烷和一氧化二氮的区域热点吗？

• 批准号: NE/H006583/1
• 负责人: Yit Arn Teh
• 金额: $ 50.39万
• 依托单位: University of St Andrews
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH006583%2F1
• 关键词: tropical; uplands; regional; hotspots; methane

Tropical ecosystems are major sources of the greenhouse gases (GHGs) methane (CH4) and nitrous oxide (N2O), which are 25 and 298 times more effective than carbon dioxide (CO2), respectively, in trapping long-wave radiation in the atmosphere. Increases in CH4 and N2O concentrations since the start of the Industrial Revolution are responsible for over one-third of global warming, and future changes in the atmospheric budgets of these GHGs have implications for the Earth's climate and environmental conditions. N2O emissions, in particular, are projected to rise in the future due to agricultural expansion and enhanced atmospheric nitrogen deposition. Recent studies of the global budgets of CH4 and N2O using satellite imagery, atmospheric measurements, and modelling suggest that significantly more CH4 and N2O are released from the tropics than previously thought due to unaccounted sources of CH4 and N2O. It is critical for us to identify and characterise these 'missing' sources if we wish to understand the current contribution of the tropics to GHG budgets. Knowledge of these 'missing' sources is also necessary for predicting how tropical GHG emissions are likely to respond to future environmental or climatic change. One strong potential candidate for these 'missing' sources of CH4 and N2O are tropical uplands. Tropical uplands have been conspicuously absent from existing atmospheric budgets, because scientific attention has largely focused on CH4 and N2O emissions from lowland forests, savannas, or wetlands. Studies from tropical uplands suggest that they are potentially large sources of CH4 and N2O, with emissions that are equal to or greater than those from lowland environments. Upland rainforests in Puerto Rico, for example, emit more CH4 than lowland forests, with emission rates that are on par with northern wetlands, the largest natural sources of CH4 worldwide. To address these gaps in knowledge, we will conduct a comprehensive study of CH4 and N2O cycling in the Peruvian Andes, using a mixture of field measurements, controlled environment studies, and mathematical modelling. Specifically, we will: 1. Investigate how CH4 and N2O fluxes vary in space and time along an environmental gradient that spans 3000 m of altitude, from lowland rainforest to upper montane rainforest. 2. Explore how key environmental variables (e.g., plant productivity, climate, soil moisture, carbon and nitrogen availability, oxygen) influence CH4 and N2O emissions. 3. Determine if existing mathematical models are able to simulate CH4 and N2O emissions from tropical ecosystems, adapting these models as necessary to better simulate field observations. 4. Determine if GHG emissions from the Andes are able to account for some of the 'missing' tropical sources of CH4 and N2O by extrapolating our field observations to the regional scale using a combination of mathematical modelling, satellite imagery, and land cover databases (i.e., GIS). The proposed research will greatly advance our understanding of CH4 and N2O emissions for an important but understudied region, and will help us determine the relative contribution of Andean ecosystems to the CH4 and N2O budgets for South America. Knowledge of the emission rates and environmental controls on CH4 and N2O fluxes from upland Andean ecosystems will also help us evaluate whether other tropical uplands are likely to be sources of CH4 and N2O, and assess their potential contributions to the global atmospheric budgets of CH4 and N2O. Lastly, the development and adaptation of mathematical models that accurately simulate tropical CH4 and N2O fluxes will allow us to predict the likely response of tropical uplands to future environmental or climatic change.

热带生态系统是温室气体 (GHG)、甲烷 (CH4) 和一氧化二氮 (N2O) 的主要来源，它们在捕获大气中的长波辐射方面分别比二氧化碳 (CO2) 有效 25 倍和 298 倍。自工业革命开始以来，CH4 和 N2O 浓度的增加是导致全球变暖的原因之一，而这些温室气体的大气收支的未来变化会对地球的气候和环境条件产生影响。由于农业扩张和大气氮沉降的增加，预计未来 N2O 排放量将会增加。最近利用卫星图像、大气测量和建模对 CH4 和 N2O 全球预算进行的研究表明，由于 CH4 和 N2O 来源不明，热带地区释放的 CH4 和 N2O 明显多于之前的预期。如果我们希望了解热带地区目前对温室气体预算的贡献，那么识别和描述这些“缺失”的来源对于我们至关重要。了解这些“缺失”的来源对于预测热带温室气体排放可能如何应对未来的环境或气候变化也是必要的。这些“缺失”的 CH4 和 N2O 来源的一个强有力的潜在候选者是热带高地。现有的大气预算中显然没有热带高地，因为科学注意力主要集中在低地森林、稀树草原或湿地的 CH4 和 N2O 排放上。热带高地的研究表明，它们是甲烷和氧化亚氮的潜在重要来源，其排放量等于或大于低地环境的排放量。例如，波多黎各的高地雨林比低地森林排放更多的甲烷，排放率与全球最大的甲烷天然来源北部湿地相当。为了解决这些知识空白，我们将结合现场测量、受控环境研究和数学建模，对秘鲁安第斯山脉的 CH4 和 N2O 循环进行全面研究。具体来说，我们将： 1. 研究从低地雨林到高山雨林，跨越 3000 米海拔的环境梯度，CH4 和 N2O 通量在空间和时间上如何变化。 2. 探索关键环境变量（例如植物生产力、气候、土壤湿度、碳和氮可用性、氧气）如何影响 CH4 和 N2O 排放。 3. 确定现有数学模型是否能够模拟热带生态系统的 CH4 和 N2O 排放，并根据需要调整这些模型以更好地模拟现场观测。 4. 结合数学模型、卫星图像和土地覆盖数据库，将我们的实地观测结果外推到区域尺度，确定安第斯山脉的温室气体排放是否能够解释一些“缺失”的热带甲烷和氧化亚氮来源（即地理信息系统）。拟议的研究将极大地增进我们对重要但研究不足的地区的 CH4 和 N2O 排放的理解，并将帮助我们确定安第斯生态系统对南美洲 CH4 和 N2O 预算的相对贡献。了解安第斯高地生态系统 CH4 和 N2O 通量的排放率和环境控制也将帮助我们评估其他热带高地是否可能是 CH4 和 N2O 的来源，并评估它们对全球 CH4 和 N2O 大气预算的潜在贡献。最后，精确模拟热带 CH4 和 N2O 通量的数学模型的开发和调整将使我们能够预测热带高地对未来环境或气候变化的可能反应。

项目成果

The effects of burning and grazing on soil carbon dynamics in managed Peruvian tropical montane grasslands

• DOI: 10.5194/bg-14-5633-2017
• 发表时间: 2017-12
• 期刊: Biogeosciences
• 影响因子: 4.9
• 作者: V. Oliver;I. Oliveras;J. Kala;R. Lever;Y. Teh

Drivers of atmospheric methane uptake by montane forest soils in the southern Peruvian Andes

秘鲁安第斯山脉南部山地森林土壤吸收大气甲烷的驱动因素

• DOI: 10.5194/bg-2016-16
• 发表时间: 2016
• 作者: Jones S

Methane and nitrous oxide fluxes across an elevation gradient in the tropical Peruvian Andes

• DOI: 10.5194/bg-11-2325-2014
• 发表时间: 2014-04
• 期刊: Biogeosciences
• 影响因子: 4.9
• 作者: Y. Teh;T. Diem;S. Jones;L. P. H. Quispe;E. Baggs;N. Morley;M. Richards;Pete Smith;P. Meir

Methane Emissions from a Grassland-Wetland Complex in the Southern Peruvian Andes

秘鲁南部安第斯山脉草原湿地复合体的甲烷排放

• DOI: 10.3390/soilsystems3010002
• 发表时间: 2018
• 期刊: Soil Systems
• 影响因子: 3.5
• 作者: Jones S

Complex controls on nitrous oxide flux across a large-elevation gradient in the tropical Peruvian Andes

• DOI: 10.5194/bg-14-5077-2017
• 发表时间: 2017-11
• 期刊: Biogeosciences
• 影响因子: 4.9
• 作者: T. Diem;N. Morley;Adan J. Q. Ccahuana;Lidia Priscila Hauraca Quispe;E. Baggs;P. Meir;M. Richards;Pete Smith;Y. Teh