Evaluation of ecosystem services in a protected mountain area: Soil organic carbon stock and biodiversity in alpine forests and grasslands

Ecosystem services (ES) evaluation is included in the environmental programs and policy strategies of protected natural areas in many countries. Alpine forests and grasslands play an important role in climate regulation but their contribution is still unknown. In this study, we estimated soil organic carbon (SOC) stocks for forest and grassland habitats by collecting samples from 87 plots in Gran Paradiso National Park (western Italian Alps). Results of the LMM show that habitat type affects SOC stock; grasslands and mixed broadleaf forests store higher SOC than mixed coniferous forests, spruce forests and larch forests. We investigate the relationships between biodiversity, SOC stock, OC stock in organic layers, soil types, forests structure and other environmental features using a canonical component analysis and a Pearson correlation matrix. The results show that biodiversity is mainly influenced by the altitude, OC stock in organic layers OH and habitats of coniferous forests. Biodiversity positively correlates to organic layers (Staphylinidae, Formicidae, Orthoptera), forests' Shannon and evenness indices (Carabidae, Formicidae, Orthoptera, Aranea, Lepidoptera) and forests' basal areas and stem density (Staphylinidae, Formicidae, Aranea). Further studies are needed to better investigate the relation between biodiversity and habitat features on ecosystem functions and thus on the provision of ES.