La evolución de las paleofloras en las cuencas cenozoicas catalanas




This paper studies the evolution of the floras in the Catalan Cenozoic basins dealing mainly with the macroflora found in diverse localities of Catalonia. Along the Cenozoic the floras in the region became tropical in the Paleogene and temperate at the end of the Pliocene. Three clearly defined periods offer rich and varied flora: a) Early Oligocene (Sarral and Cervera Localities). b) Upper Miocene (La Cerdanya basin). c) Early Pliocene (Baix Llobregat basin). According to this fossil flora, during the Cenozoic the climate in the area turns from tropical (in the Paleogene) to temperate at the end of the Pliocene, going through other intermediate climates. The main characteristic of the flora in the Eocene is the presence of a mangrove with Nipadites and Acrostichum, among other species. The Oligocene flora presents a rich and varied vegetahon with more than a hundred fossil forns. The study of this macroflora reveals that the basic community was like the laurisilva, with dominant presence of Lauraceae and Quercus originating an variety of "Evergreen sclerophyllous-laurophyllous forest".

The climates favouring the development of this vegetation, displayed high and quite constant hurnidity because of the formation of cloudiness in the mountains slopes. Coexisting with the laurisilva existed in lower topographic levels a characteristic xerophitic community. In the Lower and Middle Miocene thte climate was subtropical or tropical dry type. The Caesalpiniaceae and Mimosaceae are frequent together with other xerophytic elements. In the Late Miocene the warm tropical or subtropical flora disappeaued largely and the new vegetation is composed by mostly temperate species. A high humidity characterizes the Early Tortonian, reflected by woodland environment. Along the Pliocene the remaining warm taxa disappeared. The Early Pliocene is characterized by a hot and hurnide climate, the nediterranean species become more frequent. The Plio-Pleistocene is characterized by a temperate and humide climate and their macroflora is especially composed by actual species.