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Tesi etd-02052018-102119

Thesis type
Tesi di dottorato di ricerca
Checklist and biosystematic studies of the woody flora of Tuscany
Settore scientifico disciplinare
Corso di studi
tutor Prof. Bedini, Gianni
tutor Prof. Peruzzi, Lorenzo
Parole chiave
  • vascular flora
  • trees
  • taxonomy
  • shrubs
  • reproductive biology
  • morphometrics
  • leaf traits
  • Juniperus oxycedrus
  • herbarium specimens
  • floristic diversity
  • conservation biology
  • Cistaceae
Data inizio appello
Data di rilascio
Riassunto analitico
The main aim of the present work was to compile a complete and critical checklist of the woody flora of Tuscany, providing details at provincial level. This checklist comprises 416 taxa, of which 265 are native and 151 are non-native. Seven taxa resulted not confirmed since 1950, the occurrence of six resulted doubtful, and sixteen were new or confirmed for the regional flora, whereas thirteen taxa were excluded. The native taxa belong to 109 genera and 53 families. Rosaceae is the family richest in taxa, with Rosa being the genus with the highest number of species. On the provincial level, the province of Grosseto is the province with the highest number of native taxa, followed by the provinces of Lucca and Florence. The lowest number of taxa was documented in the provinces of Pistoia and Prato. With regard to the non-native woody flora, the highest number of non-native taxa can be found in the province of Livorno, whereas the lowest number occurs in the provinces of Arezzo and Siena. At regional level, 11% of non-native taxa are invasive, 43% naturalized and 46% casual. Asia and North America are the most common native ranges of those taxa. After the checklist was completed, I selected two case studies to be investigated more in detail.
The first case study was devoted to shed light into the taxonomy of the Juniperus oxycedrus group. Based on different essential oil composition paralleling different genotypes, Juniperus deltoides was recently segregated from Juniperus oxycedrus. Despite a clear phytochemical and molecular differentiation, J. deltoides resulted not clearly morphologically discernible from J. oxycedrus, so that it was defined as a cryptospecies. Italy represents the contact zone of their distribution, but the ranges of the two species are not sufficiently known, due to unsatisfactory morphological characterisation. To further complicate the picture, a third closely related species, J. macrocarpa, occurs all across the Mediterranean coasts. After a preliminary phytochemical analysis to ascertain the (chemo-)identities of the studied populations, I performed a morphometric investigation to test the degree of morphological distinctiveness among the taxa. According to my results, some character (e.g. leaf mucro length, leaf width, seed-cone size and seed size) resulted useful to discriminate these cryptic taxa. Finally, based on these characters, I performed an extensive revision of herbarium specimens in order to redefine the distribution pattern of the investigated species in the Central Mediterranean area. The second case study was focused on the ecology, demography and reproductive biology of Cistus laurifolius L. subsp. laurifolius, a species of particular interest from a phytogeographic point of view, surviving in Italy in a single population in Tuscany. First, an evaluation of the population size and its structure was carried out, then the breeding system was investigated, through the evaluation of the floral nectar production and the Pollen/Ovule ratio. The reproductive fitness, and leaf traits was evaluated and compared at subpopulation level and in two contrasting habitats (garrigue and underbrush). Finally, based on these results and according to IUCN protocol, an assessment of the species at regional level was carried out. The population, composed by 10,000 individuals, was inferred as fully xenogamous and reproductive performance resulted negatively affected by plant density. Furthermore, Cistus laurifolius resulted able to adjust leaf traits to maximize the carbon gain under shaded conditions. Nevertheless, plants in the underbrush developed fewer seeds with a reduced seed mass compared with the open habitat, suggesting that plants are able to modulate their vegetative traits but they are not able to offset the carbon balance deficit convoying adequate resources to reproductive traits. Overall, my results highlighted that reproductive fitness is affected by the pollination environment being positively affected by conspecific plant occurrences and negatively by canopy coverage likely limiting pollination activity. Finally, according to IUCN protocol C. laurifolius was assessed as Vulnerable (VU) at regional level.