Evaluating UK blanket peatland restoration: structure, function, and net carbon benefit

UK blanket peatlands are globally significant carbon stores, but widespread degradation has shifted them from net carbon sinks to sources. Restoration is increasingly implemented as a nature-based solution aligned with net-zero policy, attracting public and private investment. However, restoration outcomes are evaluated using surface proxies and assumed recovery timelines, limiting insight into sub-surface function and carbon efficiency. This research advances scientific understanding, restoration practice, and policy by integrating surface ecological data with sub-surface bulk chemical, structural, and carbon cost indicators to evaluate restoration effectiveness in Northern England. A mixed-methods approach was developed, combining bespoke site selection with limited samples across large, heterogeneous landscapes, condition surveys, bulk and chemical analysis, innovative 3D X-ray micro-computed tomography (μCT), and the first Life Cycle Assessment (LCA) of peatland restoration interventions. New methodologies were introduced to quantify and classify peat porosity by functional behaviour, enabling assessment of structural and functional recovery alongside net carbon benefit. Findings showed widely adopted surface indicators failed to capture sub-surface functional recovery. μCT revealed persistent drainage pathways and limited stratification, with minimal acrotelm and mesotelm development even after a decade. Turving supported atmosphere-connected pore networks indicative of a functional acrotelm, increasing surface water uptake, retention, and anoxia, suggesting its effectiveness as a revegetation strategy complimenting rewetting efforts. Carbon costs varied up to 277-fold; helicopter-installed stone dams incurred high emissions but delivered limited benefit. Greater emissions did not equate to greater function. This research informs revisions to the IUCN UK Peatland Code and provides evidence-based recommendations for best practice. It urges policy to account for sub-surface function in restoration targets and reporting, potentially extending beyond carbon. Findings support more credible carbon crediting and encourages private investment in peatland restoration as a long-term climate mitigation strategy.