Updating the woody flora of Tuscany: the first comprehensive survey, two centuries after Savi’s work

Woody species represent a significant component of the flora and vegetation of a territory. Their presence or absence directly affects the formation of whole communities and plays an important role in landscape sculpturing and in forest management. For this reason, the knowledge of woody species geographic distribution is of great theoretical and practical relevance. Tuscany, with 3810 taxa of vascular flora, is among the Italian regions with the highest diversity (1), has a high number of woody native taxa (2), and is ranked 4th in forest cover (3). However, specific researches on its woody flora are lacking. Apart from the historical contribution of G. Savi (4), the only study on the whole regional territory is a list of shrubs (5). In the context of the Global Tree Seed Bank project, promoted by Garfield Weston Foundation in collaboration with Royal Botanic Gardens, Kew (UK), we present the first comprehensive survey of Tuscan woody flora with sub-regional detail (presence/absence at province level) based on bibliographic, herbarium and field investigations, including the unpublished observations stored in the on-line database Wikiplantbase #Toscana (1). For the purpose of our study we define as woody flora those taxa whose life forms are reported as phanerophytes (P) and/or nanophanerophytes (NP) (6), including also plants occasionally growing as chamaephytes. Based on our checklist, a chorological spectrum was built at region and province level. In addition, a cluster analysis (UPGMA, Baroni Urbani & Buser's index) of provinces, based on floristic data of native taxa, was carried out. We checked 404 specific and subspecific taxa: 268 native (66.3%) and 136 non-native (33.7%). Native taxa belong to 107 genera and 53 families. Rosaceae is the most represented family (56 taxa), and Rosa is the genus with the highest number of species (23). Stenochorous taxa are 8 (3%), two of them (Rhamnus glaucophylla Sommier; Salix crataegifolia Bertol.) endemic to Tuscany. The province with the highest number of native taxa is Grosseto (196), followed by Lucca (193), while the lowest number was documented in Pistoia province (128). Only 70 taxa are shared by all the provinces, whereas 26 occur just in a single province. The regional chorological spectrum highlights a dominance of Stenomediterranean (22%), followed by Eurimediterranean (16%) and European (13%) taxa. However, considering Eurosibiric and Mediterranean species sensu lato, the former are slightly more abundant (46% vs. 40%). The same pattern can be found at province level, with the exception of Livorno and Grosseto, where Mediterranean taxa slightly outnumber Eurosibiric ones. In addition, the chorological spectra for each province highlight that Livorno and Massa- Carrara have the highest percentage of stenochorous taxa (3.1% and 2.9%, respectively). As concerns the non-native species, the highest number (78) is found in Livorno province, whereas the lowest number occurs in Siena (16). At regional level, 12 exotic taxa (9.3%) are invasive, 58 are naturalized (45%), and 58 are casual. Their native range mostly concerns Asia (27%) and N America (24%). Cluster analysis of provinces resulted in two main clusters: a first one uniting Livorno and Grosseto (encompassing the whole Tuscan Archipelago), a second joining all the remaining provinces. As regards conservation status, six taxa are included in national Red Lists (7, 8) and 77 in the Re.Na.To inventory (9) and in the annexes of regional law 56/2000.