SooSim, a landscape model for assessing mire habitat degradation and restoration

Open mires constitute a characteristic part of boreal natural landscapes, which is under various cumulative anthropogenic pressures. As a response, remaining mires are increasingly protected, and their degradation is addressed by ecological restoration (mostly drainage closure). To evaluate alternative environmental policies, there is a necessity for high-resolution landscape simulation models to assess future dynamics of mires under different management scenarios. We present such a model, SooSim, its R-script, and derivation and validation of its key parameters. SooSim iterates mire types and woody encroachment dynamics within 25 × 25 m grid at 1-year intervals. Management interventions (restoration; ditch renovation) are sequentially introduced based on priority rules in locations delineated prior to simulation. We applied SooSim to three management scenarios, compared with natural succession, until 2050 in Estonia. The ‘current’ (2022) database comprised >3.8 M mire pixels and > 7 M peatland-forest pixels (sparse-cover ones considered for mire restoration). The model parameterization, based on Lidar data, revealed rapid ongoing woody encroachment across all mire types, with significant positive feedback. The simulations revealed that, even in scenarios with intensive restoration (2500 ha annually), open mire conditions are reduced by >10 % until 2050, while few mire types lose >1 % in area. Ditch renovations mostly reduced restoration perspectives in currently forested peatlands. Thus, SooSim explicitly depicts a decision-making dilemma where mire restoration is time-sensitive but also uncertain. To address this and related land-use dilemmas in the environmental policy, landscape models such as SooSim have further importance as visualization tools to explain complex processes to a wide range of stakeholders.