Environmental and ecological drivers of tropical peatland methane dynamics across spatial scales

热带泥炭地是全球重要的碳储存地，也是大气甲烷（CH 4）浓度上升的重要来源。CH 4是一种强大的温室气体，在100年内推动气候变暖的能力是二氧化碳（CO2）的25倍，迄今为止造成了23%的变暖。在COP 26上，美国，欧盟和其他国家宣布了全球甲烷承诺，以遏制全球甲烷排放，试图将全球变暖控制在1.5摄氏度。然而，大气中的甲烷浓度正在上升，有证据表明热带湿地和泥炭地是重要的来源，特别是在南美洲。造成这一现象的环境原因尚不清楚。热带泥炭地遍布整个热带地区，但迄今为止，大多数研究都集中在东南亚。然而，最近的研究表明，在中非和南美洲都有广泛的泥炭沉积，但这些生态系统的动态仍然相对不足。泥炭是由部分降解的植物材料形成的，包括落叶和根。在淹没、低氧条件下的逐渐分解驱动CH 4的产生。生产率和排放率受水文、养分供应、地形和植被等因素的综合控制。其中许多因素在空间上可能不同，并随时间而变化。这限制了我们将地面测量的CH 4排放量扩大到更广泛地区的能力，因此使我们无法充分评估区域泥炭地对全球CH 4循环的贡献。在本项目中，我们将解决这些不确定性，并对热带泥炭地甲烷排放的环境和生态驱动因素产生新的综合理解，并首次将其完全纳入数学模型。这将使我们能够更准确地将CH 4排放量的现场测量扩展到更广泛的区域，使我们能够评估热带泥炭地CH 4通量对大气CH 4浓度上升的贡献。我们将在秘鲁的Pastaza-Maranon前陆盆地的南美洲泥炭地进行新的长期CH 4通量测量。我们将把我们的通量测量与持续监测生态系统生产力和泥炭特性和养分可用性随时间的变化相结合，并在植被类型和养分可用性不同的泥炭地进行监测。我们将使用一个统计工具，使我们能够确定哪些因素是最重要的预测CH 4通量。我们将使用由此产生的结果来修改现有的模型（ECOSSE），以更好地解释这些过程，从而更准确地放大更广泛地区的CH 4通量。为了帮助开发和测试我们的统计工具和ECOSSE模型，我们将利用新收集的数据，从中非泥炭地，这也是一个地区的CH 4通量动态研究不足，但似乎有许多相似之处，南美洲的植被类型和营养制度。然后，我们将应用我们新开发的统计工具和模型，更准确地将我们在南美泥炭地的CH 4通量测量提升到更广泛的区域。我们还将能够使用我们新开发的模型来测试对该地区湿地甲烷排放量增加的各种解释，调查原因，包括水资源状况，植被投入和气候变暖的变化。从项目早期开始，并持续整个过程，我们将与英国，秘鲁和国际合作伙伴密切合作，以确定区域和国际利益相关者。我们将共同开发我们的研究，并将我们的项目发现转化为简单的摘要，为政策制定者提供信息，并提高人们对泥炭地过程对全球环境变化敏感性的认识。

Tropical peatlands are a globally important carbon store, and a significant source of rising atmospheric concentrations of methane (CH4). CH4 is a potent GHG, 25 times more powerful at driving climate warming than carbon dioxide (CO2) over 100 years, and is responsible for 23% of warming to date. At COP26, the US, EU and others announced the Global CH4 Pledge to curb global CH4 emissions in an attempt to keep global warming at 1.5C. However, atmospheric CH4 concentrations are rising with evidence pointing to tropical wetlands and peatlands as significant sources, particularly those in South America. The underlying environmental causes of this are not well understood. Tropical peatlands are found throughout the tropics but to date most research has focussed on Southeast Asia. However, recent research has demonstrated extensive peat deposits across both Central Africa and South America but the dynamics of these ecosystems remain relatively understudied. Peat is formed from partially degraded plant material, including leaf litter, and roots. Gradual decomposition under flooded, low oxygen conditions drives CH4 production. Rates of production and emission are controlled by a combination of factors including hydrology, nutrient availability, topography, and vegetation. Many of these factors can vary spatially and change over time. This limits our ability to scale up CH4 emissions measurements made on the ground to the wider region, and therefore prevents us from fully assessing the contribution of regional peatlands to global CH4 cycling. In this project, we will address these uncertainties, and generate a new integrated understanding of the environmental and ecological drivers of CH4 emissions from tropical peatlands, and incorporate them fully in mathematical models for the first time. This will allow us to more accurately upscale field based measurements of CH4 emissions to the wider region, allowing us to assess the contribution of tropical peatland CH4 fluxes to rising atmospheric concentration of CH4. We will undertake new long-term CH4 flux measurements across South American peatlands in the Pastaza-Maranon Foreland Basin in Peru. We will integrate our flux measurements with ongoing monitoring of ecosystem productivity and changes in peat properties and nutrient availabilities over time, and across peatlands that differ in vegetation type and nutrient availability. We will use a statistical tool that will allow us to identify which factors are most important for predicting CH4 fluxes. We will use the outcomes from this to modify an existing model (ECOSSE) to better account for these processes allowing more accurate upscaling of CH4 fluxes for the wider region. To help develop and test our statistical tool and ECOSSE model, we will make use of newly collected data from Central African peatlands, a region which is also poorly studied in terms of CH4 flux dynamics, but appears to have many similarities to South America in terms of vegetation types, and nutrient regimes. We will then apply our newly developed statistical tool and model to more accurately upscale our CH4 flux measurements across South American peatlands to the wider region. We will also be able to use our newly developed models to test various explanations for the observed increase in CH4 emissions across the region's wetlands, investigating causes including changes in water regimes, vegetation inputs, and climate warming. Beginning early in the project, and continuing throughout, we will work closely with partners in the UK, Peru and internationally, to identify regional and international stakeholders. Together, we will co-develop our research, and translate our project findings into lay summaries to inform policymakers, and raise awareness of the sensitivity of peatland processes to global environmental changes.