Palynology and Mediterranean vegetation history

Abstract

The history of Mediterranean vegetation can be outlined using pollen grains contained in lacustrine, marine and other sediments. These sediments have recorded very important vegetation changes during recent geological times. For example, during the last 6 Ma (million years), the effects of different events acting at regional (e.g. the Messinian salinity crisis between 5.96 Ma and 5.33 Ma) and global (expansion of the Arctic ice at ca 2.6 Ma) scales produced a progressive decrease and final disappearance of tropical and subtropical taxa. However, prior to the start of the Quaternary the Mediterranean flora still included a consistent number of tropical and subtropical arboreal taxa accompanying deciduous and partly evergreen trees that have persisted until today. The most important features of the vegetation history of the Quaternary consist in the fact that vegetation adapted to climate changes due to changes in orbital cyclicity, alternating between glacial and interglacial periods. The more widespread vegetation types were steppe and grassland formations during the dry and cold glacial periods whereas either deciduous or evergreen forests were characteristic of interglacial periods. These cold-dry to warmhumid climate cycles became more and more intense towards the present. During the second half of the present interglacial, after the mid-Holocene, joint actions of increasing dryness, climate oscillations and human impact led to the present day Mediterranean plant landscape. It is however not clear how far the causation of this spread of evergreen taxa was climatic or human. One of the most exciting challenges is the prediction of the future course of Mediterranean vegetation. In this perspective a consistent help, not fully explored yet, can be found in aeropalynology, recording the pollen transported in the air. Together with modern surface samples, these data act as modern analogues. Though it probably does not represent the same past vegetational composition, the current pollen rain is the only basic reference on which our comparative approach can rely. Present trends are interpreted and future scenarios can be hypothesized just using a combination of aero-and archaeo-/palaeo-palynological approaches.

Light and shadows in the evolution of South European stenonoid horses

“…A gradual renovation of large mammal communities occurred in a period recording the fi rst evidence of the incoming marked climatic upsetting known as the Mid-Pleistocene Revolution/Transition (see e.g. Magri and Palombo 2013, Sadori et al 2013, Palombo 2014, 2017, and references therein). A few anagenetic processes within already present phyletic lineages, and discrete dispersal bioevents of taxa originally coming from both Asia and Africa led to the appearance of new taxa and triggered new faunal dynamics.…”

“…Together with the environmental changes, the increase in aridity and some spread of savanna-like environments and grasslands (e.g. Pons et al 1995, Tzedakis et al 2006, Joannin et al 2007, Magri and Palombo 2013, Sadori et al 2013, a shift towards smaller size, with some oscillations, and slender limb proportions is traceable in the E. major-E. suessenbornensis lineage. Climate and environmental changes most likely also led to the disappearance of E. stenonis and horses of the E. senezensis group.…”

Biogeografía analítica de la pteridoflora del Arco de Alborán: Consecuencias para su status de protección

“…Su origen geológico surge por la aproximación de la placa tectónica africana y la microplaca ibérica durante el terciario (65 Ma) (Flinch, 1993). Tal aproximación jugó un papel fundamental para el intercambio biológico entre los dos continentes durante el Messiniense (5 Ma) al establecerse puentes de comunicación por la desecación del Mediterráneo, hito de excepcional importancia por el cambio profundo de la composición florística y de vegetación (Sadori et al, 2013). Estos eventos geológicos, y sus consecuencias climáticas, han sido los responsables de la importante diversidad florística y fitocenológica del Arco Alboránico (Medail & Quézel, 1999), con un alto número de relictos, desde los paleotropicales lauroides cuya presencia es previa a la crisis messiniense, a los iranoturanianos incorporados durante esa crisis o a los acantonamientos glaciales (Pichi-Sermolli, 1979, Allen, 2003.…”

Habitat turnover in Iberian and Italian lizards: Is it climatically, spatially, or phylogenetically determined?

“…This diversity is generated by the presence of taxa of different origins, due to the position of the Mediterranean Basin as a biogeographical crossroad (Médail & Diadema, 2009). Climate undoubtedly plays an important role in determining this diversity, given that the relatively warm and humid conditions of the Mediterranean region are suitable for subtropical and temperate boreal taxa (Sadori et al, 2013). However, within homogeneous climate belts, the composition of these communities can show important variation, depending on local factors more related to the specific nature of habitats and the interactions (competition or predation) established with syntopic species (Lloret et al, 2005; Silvestre et al, 2021).…”