New plant communities to define the southern boundary of the European Atlantic Province in mainland Portugal

This study identifies and analyzes the plant communities that allow the definition of the geographic limits between Temperate and Mediterranean macrobioclimates, for the center of Portuguese mainland. The altitude of Serra da Estrela, Açor and Lousã, combined with the increase in atmospheric humidity, allows the presence of vegetation typical of a Temperate macrobioclimate. Thus, based on the phytosociological methodology, floristic relevés were carried out in order to identify the series of vegetation existing in these territories. Through these relevés carried out, four new plant associations were identified: Cytisetum grandifloro-striati ass. nova, Scrophulario grandiflorae-Sambucetum nigrae ass. nova, Pruno lusitanicae-Coryletum avellanae ass. nova that lives in the submediterranean bioclimatic variant, mesotemperate humid to hyper-humid. A new association namely Genisto falcatae-Quercetum broteroanae ass. nova with two subassociations were also identified. Based on the vegetation distribution, new biogeographic limits are proposed. Thus, it was intended to identify the southern limits of the European Atlantic Province (Atlantic Orolusitania Subrovince) based on the vegetation cover, namely the distinction between the Estrela Sierran District and a new Biogeographical District, the Alvo-Gardunhense.