Quaternary disappearance of tree taxa from Southern Europe: timing and trends

https://hal.archives-ouvertes.fr/hal-01806165/document

Climate changes in the central Mediterranean and Italian vegetation dynamics since the Pliocene

The flora and vegetation of Japan

The Macaronesian laurel forests (MLF) are dominated by trees with a laurophyll habit comparable to evergreen humid forests which were scattered across Europe and the Mediterranean in the Paleogene and Neogene. Therefore, MLF are traditionally regarded as an old, 'Tertiary relict' vegetation type. Here we address the question if key taxa of the MLF are relictual. We evaluated the relict hypothesis consulting fossil data and analyses based on molecular phylogenies of 18 representative species. For molecular dating we used the program BEAST, for ancestral trait reconstructions BayesTraits and Lagrange to infer ancestral areas. Our molecular dating showed that the origins of four species date back to the Upper Miocene while 14 originated in the Plio-Pleistocene. This coincides with the decline of fossil laurophyllous elements in Europe since the middle Miocene. Ancestral trait and area reconstructions indicate that MLF evolved partly from pre-adapted taxa from the Mediterranean, Macaronesia and the tropics. According to the fossil record laurophyllous taxa existed in Macaronesia since the Plio- and Pleistocene. MLF are composed of species with a heterogeneous origin. The taxa dated to the Pleistocene are likely not 'Tertiary relicts'. Some species may be interpreted as relictual. In this case, the establishment of most species in the Plio-Pleistocene suggests that there was a massive species turnover before this time. Alternatively, MLF were largely newly assembled through global recruitment rather than surviving as relicts of a once more widespread vegetation. This process may have possibly been triggered by the intensification of the trade winds at the end of the Pliocene as indicated by proxy data.

/pdf/biogeography-of-mediterranean-hotspot-biodiversity-re-53c6wqtf7c.pdf

Biogeography of Mediterranean Hotspot Biodiversity: Re-Evaluating the 'Tertiary Relict' Hypothesis of Macaronesian Laurel Forests

The evolution of plant ecosystems during the Cenophytic was complex and influenced by both abiotic and biotic factors. Among abiotic forces were tectonics, the distribution of continents and seas, climate, and fires; of biotic factors were herbivores, pests, and intra- and interspecific competition. The genus Quercus L. (Quercoideae, Fagaceae) evolved in this context to become an established member of the plant communities of the Northern Hemisphere, commencing in the Paleogene and spreading to a diverse range of environments in the later Cenozoic. Its palaeontological record, dominated by leaves and pollen, but also including wood, fruits and flowers, is widespread in Eurasia and North America. Consequently, a great number of species have been described, from the 19th century to the present day. Although Quercus is currently an ecologically and economically important component of the forests in many places of the Northern Hemisphere and Southeastern Asia, no comprehensive summary of its fossil record exists. The present work, written by an international team of palaeobotanists, provides the first synthesis of the fossil history of the oaks from their appearance in the early Paleogene to the Quaternary.

The Fossil History of Quercus

Dunarobba and Pietrafitta are two outstanding fossil sites, which provide us with a glimpse on central Italian palaeoenvironments during two different time spans. The still poorly dated Dunarobba succession is framed, mainly on the basis of continental mollusc biochronology, within the Piacenzian-Gelasian interval, whereas the Pietrafitta one is reliably dated to the Calabrian thanks to vertebrate biochronology. Here we add several new palaeobotanical data for the two sites and we provide for the first time an overview of the stratigraphic, sedimentological, palaeontological and palaeoenvironmental results so-far obtained. We also review the palaeobotanical evidence concerning the neighbouring sites of Cava Toppetti I/II, Fosso Bianco, Torre Picchio and Villa San Faustino. On the basis of the available datasets we conclude that the Dunarobba Fossil Forest, with several large conifer trunks in upright position, was produced by an ancient swamp vegetation dominated by Glyptostrobus europaeus, and including few other woody (Alnus, Cephalanthus, Cornus) and herbaceous (Carex, Cladium, Schoenoplectus) plants. Rich water-transported fruit and seed assemblages and pollen data indicate that the well-drained palaeoenvironments around the Dunarobba palaeo-swamp were covered by a forest having a floristic affinity to the modern Mixed Mesophytic Forests of East Asia, as proved by the occurrence of Cryptomeria, Eurya, Sinomenium, etc. The disappearance of the Glyptostrobus swamp forest was due to the establishment of well-drained palaeoenvironmental conditions, testified by a

/pdf/the-plant-record-of-the-dunarobba-and-pietrafitta-sites-in-3s2kvby4h4.pdf

Sergio Gentili

Papers

The plant record of the dunarobba and pietrafitta sites in the plio-pleistocene palaeoenvironmental context of central italy