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

Lead Research Organisation: Cranfield University


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.


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