14C dating of peat surface - emitted dissolved fluvial CO2 carbon to support management and decision-making for UK Lowland peatlands

Measurable restoration targets, and indicators of success for restoration are critically required for restoration programmes to successfully measure and appraisal of interventions. 

Traditionally this has been done by a combination of hydrology monitoring, vegetation surveys and GHG emissions monitoring. These methods can be both costly in terms of time and money and are not always included as part of traditional UK-based conservation and restoration funding criteria written by the funding providers, such as landfill tax and government funding.

They also require trained practitioners or partnership working (e.g. with academia or specialist consultancies) to do effectively, especially at the scale needed to meet the target of 282 thousand Ha of peat being actively under restoration by 2050, as set by the British government as part of the Peat Action Plan (PAP) in 2021. 

One of the major challenges of assessing restoration efficacy is the lengthy period needed to reach any restoration targets and the therefore associated long-term monitoring needed to measure this. The processes at work can take decades to reach completion, resulting in costly and far-sighted monitoring programmes.  

This research aims to develop a tracer for peatland status based on elucidating the extent to which old C stored within degraded and rehabilitated peatland sites is being emitted. It will do this by delineating the relationships between the age of respired soil carbon (C) being lost from peatlands and current, historical, and restorative land management of sites. 

This research applied highly novel application of ¹⁴CO₂ and dissolved ¹⁴CO₂ (D¹⁴CO₂) Carbon dating of the soil and fluvial emissions across the time chrono-sequence of a lowland-raised bog restoration programme and combine with data on CO₂ soil emissions (NER) and primary productivity data (GPP) to aid in the characterisation of emissions for each site. This approach aims to provide an insight into the stability of the peat horizon, the role of modern and older carbon mobility plays across restoration strategies and the estimated depth at which emissions originate. Emissions were captured using molecular sieves connected from closed chambers, with flux passively sampled over a 1-month period. This was combined with fluvial D¹⁴CO₂ samplers deployed in parallel in adjacent ditches to compare the difference in ages between soil respiration and fluvial emissions.

 This simple tracer could revolutionise peatland conservation science through providing an accessible, quantitative approach to assessing the extent to which C lost is either dominated by modern C gained from recent plant grown or C respiration of older, deeper organic matter stores (representing a net loss of stored C to the atmosphere). As reinstatement of stable, long-term C storage is one of the key aims of conservation bodies, government, and landowners, assessing this directly would seem an obvious and important measure especially with funding shortfalls identified leading to a more blended funding approach to peatland restoration.