Plant Biogeography and Vegetation Patterns of the Mediterranean Islands

Abstract

With about 11,100 islands and islets of which ca. 250 are regularly inhabited by human, the Mediterranean Sea represents one of the regions of the world with the most islands and archipelagos. These numerous islands represent a significant component of the Mediterranean biodiversity, notably with the presence of range-restricted species and peculiar vegetation types. The aim of this review is to provide a balanced view of this highly diverse phytoecological heritage, but also taking into account the medium sized islands and the smaller ones that have not been highlighted so far. Mediterranean islands constitute both a museum for ancient lineages (paleoendemic taxa) and cradle for recent plant diversification. The complex historical biogeography (paleogeographical events of the Neogene, Messinian salinity crisis, climatic and eustatic changes of the Pleistocene, influence of glacial events) has profoundly influenced the current patterns of plant diversity. These insular landscapes were also precociously impacted by prehistoric man, possibly by Neanderthals. Among the 157 large Mediterranean islands (i.e. with a surface area exceeding 10 km 2 ), 49 have a surface greater than 100 km 2 .The main patterns anddynamics of vegetationon the largests islands (Balearic Islands, Corsica, Sardinia, Sicily, Croatian islands, Greek islands, Crete, Cyprus) are summarized. Then, the specific ecosystem functioning (disturbance, plant-animal interac-tions) and vegetation structures of the small Mediterranean islands (i.e. a surface area less than 10 km 2 or 1000 ha), are highlighted by evoking successively the small rocky islands, the volcanic ones, and the sandy and flat islands. Owing to their uniqueness and fragility, Mediterranean islands urgently need some integrated and ambitious conservation planning, aiming at the long-term preservation of their outstanding biotic and cultural heritage.

The Endemic Vascular Flora of Sardinia: a Dynamic Checklist with an Overview of Biogeography and Conservation Status

“…Moreover, geographical biases in species discovery and descriptions have been often found [e.g., 61,62] and should always be considered when discussing quantitative features of species checklists. Our results are in accordance with those recently published by Thompson [12] and Médail [28], who reported similar percentages of endemic vascular plants of Sardinia. Furthermore, it is noteworthy that the percentages of endemic vascular plants exhibited by Sardinia are similar or even slightly higher than those of the rest of Mediterranean large islands (see summary presented in Médail [63] and comparable to those showed by some tropical continental islands such as the large island of Hainan, with a size similar to Sardinia (33,210 km 2 [64]), or many small oceanic islands of Eastern Polynesia [65].…”

“…Furthermore, it is noteworthy that the percentages of endemic vascular plants exhibited by Sardinia are similar or even slightly higher than those of the rest of Mediterranean large islands (see summary presented in Médail [63] and comparable to those showed by some tropical continental islands such as the large island of Hainan, with a size similar to Sardinia (33,210 km 2 [64]), or many small oceanic islands of Eastern Polynesia [65]. All these comparative data sustain the inclusion of Sardinia and the other Tyrrhenian islands within the "hottest" global hotspots of plant biodiversity, as already underlined by several authors [12,23,28,63,66,67].…”

“…The distribution of several Tyrrhenian endemic plants shared between these islands reflects this palaeogeographical event. Some examples are Arenaria balearica [115], Arum pictum, Helicodiceros muscivorus [4], Soleirolia soleirolii and Teucrium marum [28,109], or the ancestral to the vicariant species belonging to genera like Cymbalaria or Thymus [6,7]. The Messinian salinity crisis of the Late Miocene is another biogeographical event caused by the closure of the Mediterranean-Atlantic connection.…”

Conservation and Phylogeography of Plants: From the Mediterranean to the Rest of the World

“…The changes caused by anthropogenic habitat destruction and fragmentation can have deleterious demographic and genetic consequences [10]. Conservation biology is essential to preserve the evolutionary and functional heritage of biodiversity by the preservation of current genetic diversity and the diversification processes that are taking place at the species level [11,12]. Phylogeography analyzes colonization and expansion histories based on phylogenies of species and supra-species, which results are relevant for units of conservation [2,13].…”

Niche Differentiation at Multiple Spatial Scales on Large and Small Mediterranean Islands for the Endemic Silene velutina Pourr. ex Loisel. (Caryophyllaceae)

“…Most Mediterranean islands are once-connected continental fragments or land-bridge islands [21] that were historically linked to adjacent continents ("continental islands" sensu [22]). On these islands, species richness is often significantly correlated with both area and elevation, but poorly with distance from continental areas, because their floras were very similar prior to isolation [21,[23][24][25][26]. Of major importance for species diversity on large Mediterranean islands is thus the elevation gradient and habitat diversity [21].…”