Modeling the effects of rewilding on soil carbon dynamics and greenhouse gas mitigation in Europe

Rewilding has emerged as a transformative restoration approach, promoting ecosystem self-regulation by restoring key processes like trophic complexity and reducing human influence. As a nature-based solution, rewilding plays a vital role in both climate adaptation and mitigation, offering pathways to address challenges like biodiversity loss and carbon sequestration. Trophic rewilding, in particular, focuses on reintroducing keystone species such as large herbivores to restore ecosystem functionality. While rewilding's impacts on biodiversity and aboveground carbon dynamics are increasingly documented, its influence on soil carbon storage—particularly the underlying dynamics—remains poorly understood. Large herbivores can influence soil carbon both directly and indirectly through mechanisms such as trampling, defoliation, and defecation. Trampling alters soil bulk density and porosity, affecting soil aeration and microbial activity. Defoliation simulates biomass removal, redistributing aboveground carbon inputs to the soil. Defecation contributes to nutrient cycling and modifies the C/N ratio in soils. Despite observational studies, laboratory experiments, and meta-analyses pointing to these mechanisms, there is a lack of comprehensive modeling frameworks to capture their cumulative effects on soil carbon dynamics.

Here we used LPJ-GUESS, a dynamic vegetation model (DGVM), to simulate rewilding scenarios across Europe, from single points to regions. The point estimates are based on data from sites in Poland and Denmark; the Białowieża Forest (BIA) in Eastern Poland, one of Europe's last lowland primeval forests, where 23 years of herbivore exclusion has allowed undisturbed regeneration within fenced areas, and the Mols Laboratory (ML), a former agricultural landscape in Denmark rewilded since 2016. These sites represent two stages of a ‘Northern European rewilding trajectory’: BIA as a late-successional system, and ML as a system in a state of early secondary succession. Preliminary results indicate that the model performs well in simulating single-point scenarios of passive rewilding and realistic land-use and land-cover changes (LUCC). Comparisons with global MODIS and FLUXNET-derived daily GPP data yield R² values of 0.86 for Białowieża and 0.84 for Mols.

Building on this, we aim to enhance LPJ-GUESS by representing animal-driven processes such as trampling, defoliation, and defecation in the model, to compare the impact of trophic (animal introductions) and passive rewilding (land abandonment), continued agriculture, and traditional grassland nature management (mowing) on carbon dynamics. Future work will explore the regional impacts of large herbivores on soil carbon dynamics and greenhouse gas fluxes through advanced modeling and field data integration. This research will contribute to understanding the role of large herbivores in ecosystem restoration and carbon cycling, supporting the emerging discipline of zoogeoscience.