Multi-proxy high-resolution geochemical analysis reveals ecological baselines and evaluates potential restoration trajectories in European ombrotrophic peatlands

The application of a multi-proxy approach to evaluate ecological baselines with the purpose of analysing potential restoration trajectories in ombrotrophic bogs is limited. Moreover, the effectiveness and robustness of different palaeoecological and geochemical indicators to evaluate past and current ecological status in peatlands is not well established. Here, depth profiles of six peat cores were segmented into pre-disturbance, disturbance and post-disturbance layers using constrained hierarchical structuring to evaluate reconstructed water table depth (WTD), peat decomposition proxies, nutrient concentrations, Fe/Ti ratios and macrofossil abundances. These indicators were used to assess the peatland ecosystem status along a degradation-restoration continuum. Peat decomposition indicators were found to be robust proxies for peat degradation status due to their stability over time, whereas redox-sensitivity of N and P were deemed unreliable parameters for defining ecological baselines. Sphagnum dominance and minimal vascular plant abundance were considered important in assessing peat degradation status and subsequent restoration potential. Reconstructed WTD, when paired with Fe/Ti ratios, was a potentially useful proxy for the quantification of current WTD. This research underlines the importance of multi-proxy approaches for the assessment of peatland ecological status, and subsequent analysis of ecological baselines and restoration trajectories. The results reaffirm the need of a site-specific approach, providing practitioners with restoration guidelines and a gradient-based framework for the evaluation of peatland restoration potential.