Dottorato in BIOLOGIA AMBIENTALE ED EVOLUZIONISTICA

Titolo della tesi: Plant diversity and functions in mountain semi-natural grasslands under different management intensities

European semi-natural grasslands are secondary habitats maintained by traditional agriculture practices. They are among the most important biodiversity hotspots worldwide and ensure the performance of multiple ecosystem functions and services. Despite their high relevance for biodiversity conservation and society, semi-natural grasslands are among the ecosystems with the worst conservation status in Europe threatened by shifts in management intensity. Thus, the European Union lays down special protection measures in order to maintain traditional agricultural practices while ensuring the sustainable management of natural resources. Despite their good proposals, many evidences highlight the need to implement and redesign several measures and demand for innovative approaches to sustainably improve biodiversity conservation with the consequent increasing in ecosystem functioning and stability. In this context my PhD aimed at analyzing the complex interactions among management features, environmental factors, habitat conservation state, and plant species diversity, also considering the support of semi-natural grasslands to livestock grazing and insect pollinators. The study was conducted on dry calcareous semi-natural grasslands distributed along a wide latitudinal and altitudinal range across Italy and Switzerland, by using original dataset with detailed multi-disciplinary information including floristic data, functional traits, environmental factors, as well as management and political features. The work encompassed three chapters supported by complex analyses, such as structural equation models and a machine learning approach, and all of them submitted to valid scientific journals. The findings demonstrated the importance of different drivers in determining both habitat conservation state, plant species diversity and functions, in particular the support to livestock grazing. The complex interactions among management activities and environmental factors determined the deviance of the habitat from the reference state and the different support to higher trophic levels. Moreover, the results suggested that the spatial scale at which European measures are designed and applied is a crucial point for the conservation of dry semi-natural grasslands, and management guidelines should be implemented as locally as possible to account for the distinctive features of local stakeholders as well as for fine-scale environmental conditions. Moreover, the different influence of local drivers on the facets of plant diversity and habitat conservation state suggest that the management of semi-natural habitats should be carefully tailored based on specific conservation objectives, with a thorough assessment of the conservation value of semi-natural grasslands accounting also for functional and phylogenetic diversity. Finally, the study proposed an innovative easy-to-use method to measure an important flower functional trait opening future opportunities to deepen the role of the dry semi-natural grasslands in supporting insect pollinator communities.