A trip through the vegetation of the Iberian Peninsula, from the Devonian to the present
The Mediterranean region is a renowned hotspot of plant biodiversity. It hosts some 25000 plant species, about half of them being endemics. Some species have been present for many million years, or even originated here, whilst others arrived much more ‘recently’. Since the appearance of the earliest land plants, its vegetation has been continuously changing as new species appeared, others arrived from more or less remote regions, and others went extinct.
The Iberian Peninsula, in the westernmost end of the Mediterranean basin, has witnessed much of this dynamic process of vegetation change. Since the Carboniferous forests of arborescent lycopsids and sphenophytes, up to the present mixture of malacophyllous and microphyllous shrubs, annuals, sclerophylls and deciduous trees and shrubs, many different taxa and vegetation types have coexisted here. These include gymnosperm forests, ferns, mangroves, laurel forests, shrublands, steppes… In some cases, vegetation change was driven by global processes (e.g. global climate changes, tectonic movements), but the fate of many other taxa was mainly determined by particular features of the Iberian Peninsula, such as being surrounded by sea, its proximity to the African continent, or its topographic and geological diversity. These features enabled, for instance, the persistence of a significant number of relict taxa from past climates that went gradually extinct in many other regions, but found in the Iberian Peninsula suitable long-term refugia. Most importantly, the biogeography of Iberian species and vegetation serves to answer more fundamental questions in plant evolution and biogeography, such as the radiation of angiosperms during the early Cretaceous, the role of man and fire in changing species composition, the importance of land-bridges for plant migrations, or the role of refugia on species persistence and range dynamics.
Profs. José Carrión & Suzanne Leroy have now edited a fascinating volume in Review of Palaeobotany and Palynology that summarises all what we know about plant biodiversity and vegetation dynamics of the Iberian Peninsula during the last 400 million years. Such a compilation was much needed, as most of the information occurred as ‘grey literature’ (symposia proceedings, unpublished PhD theses, etc) hardly available for an international (or even national) audience. In this special issue, inferences about past vegetation dynamics are mainly based on the fossil record. We modestly contribute with a review of the past range dynamics of many Iberian tree species as inferred from two other powerful tools of historical biogeography: phylogeography and species distribution modelling. I plan to provide a summary of the latter in a future post. For now, I hope you enjoy reading such an inspiring history of species diversification, migrations and extinctions through time.
