Native plants for ecological restoration in Italy: taxonomy and species selection

Grasslands represent one of the most widespread and ecologically significant terrestrial biomes, covering roughly 30-40% of Earth’s land surface and providing a variety of vital ecosystem services. Among their dominant species, perennial grasses are particularly important for ecosystem, consisting often in the keystone and dominant species of these habitats, and partaking a critical role in the correct functioning of the vast majority of these ecosystemic services. Because of their undiscussed importance, perennial grasses have been the main focus when talking ecological restoration and protection of grasslands. Within the grass family (Poaceae), Festuca L. is a globally distributed and ecologically diverse genus, with fine-leaved taxa (Festuca sect. Festuca) playing central roles in the composition of Eurasian steppes, alpine meadows, and semi-natural grasslands of Europe. Despite their ecological importance, the taxonomy of Festuca remains one of the most challenging in the grass family, with morphological convergence, polyploidy, hybridization, and incomplete lineage sorting leading to long-standing uncertainty in species delimitation. These taxonomic criticalities are not to be overlooked as they go far beyond the disciplines of taxonomy and systematic botany. In fact, this type of knowledge is fundamental to many other seemingly unrelated disciplines, as reliable species identification is fundamental to ecological restoration, conservation planning, and biodiversity monitoring. This PhD project focuses on the Festuca stricta-valesiaca complex, a particularly intricate group of fine-leaved fescues distributed across Eurasia, focusing on the taxa that naturally occurs in the Alps and Apennines. Taxa within this complex have been variously interpreted as species, subspecies, or hybrids, and their boundaries remain controversial. The aim of the study is to integrate morphological, cytogenetic, and molecular approaches to achieve a clearer understanding of taxa boundaries, evolutionary relationships, and nomenclatural stability within the group, for further application in ecological restoration projects. To this end, 987 individuals from 66 populations were collected across the Alps and Apennines, supplemented by herbarium research and historical type material consultation in different European herbaria. Morphological variation was quantified using 32 characters from vegetative, reproductive, and anatomical traits, with analyses conducted through ordination and canonical discriminant methods. Flow cytometry was employed on fresh and recent herbarium material to assess ploidy levels and cytotype variation across populations. Finally, for a limited number of individuals, genomic data were generated using ddRAD sequencing, allowing phylogenetic inference of relationships within the complex and between taxa. The analyses revealed clear differentiation between taxa with lower ploidy (F. valesiaca, F. sp. nova) and the more complex group of polyploid taxa (hexaploids, octoploids, decaploids), which showed in some cases morphological overlap but also evidence of reproductive isolation. Several diagnostic morphological characters, particularly leaf cross-section anatomy, scabridity, spikelets elements size and pubescence, were confirmed as useful for discrimination, though many boundaries remain blurred by gradual variation and shared traits. Flow cytometry confirmed known ploidy levels but also identified unexpected cytotypes in the Apennines, suggesting overlooked diversity or some polyploidization events. Phylogenomic analyses showed promising early results and laid a solid base for a more complete study of the group in the future.