Assessing the potential ecological functions, ecosystem services and disservices of megaherbivore rewilding in traditional rural wood-pastures

Traditional rural wood-pastures are threatened by the loss of wild herbivory and traditional agrosilvopastoral practices, promoting woody encroachment, habitat homogenization, and erosion of biodiversity and cultural values. Megaherbivore rewilding has been proposed as a strategy to restore disturbance regimes in these seminatural landscapes, but its socioecological implications remain uncertain. Using Italy as a representative case study, we reconstructed an early Holocene, preagricultural baseline from fossil records to identify candidate megaherbivores for reintroduction across Alpine, Continental, and Mediterranean biogeographical regions. We compared extant and potential assemblages in functional diversity, vegetation consumption, grazing vs. browsing balance, and seed dispersal potential, assessed the sensitivity of conservation priority habitats to increased herbivory, and reviewed literature through a SWOT analysis of ecosystem services and disservices. The potential assemblage comprised ten species, including extant, range restricted, new native, and extinct taxa. Reintroductions would generate uneven functional gains, with limited change in the Alpine region but stronger expansion in the Continental and especially Mediterranean regions, where functional dispersion would increase from 0.46 to 0.64 and vegetation consumption from 4.45 to 10.58 t/kmq/year. Rewilding may shift assemblages towards grazing, potentially helping to limit woody encroachment and reduce fuel loads, but increasing risks for habitats with low-to-moderate herbivory requirements. The SWOT analysis highlighted opportunities for nature-based tourism, rural livelihoods, damage-prevention measures, and integrated wildlife, livestock, human health surveillance, alongside threats related to crop damage, disease transmission, road collisions, management costs, and social conflict. Overall, megaherbivore rewilding should be regarded as a context-dependent restoration strategy requiring spatially explicit planning, density thresholds, and participatory governance.