Origin and peculiarities of Mediterranean island floras

Abstract

The countless small to minute islets of the Mediterranean Sea show a surprising floristic originality. They are ideal natural laboratories in which the biogeographer can study questions of long-range dispersal and migration, species turnover, and population dynamics. The larger islands have functioned as conservatories for mid-Tertiary floras to which they have provided shelter from the climatic fluctuations of the Pleistocene era and correlated shifts of vegetation belts. Their native flora was presumably impoverished after long-lasting insular isolation but that deficit has since been replenished by the activity of Man. Their rate of endemism is comparatively high. Vulnerability of island floras, as evidenced by documented cases of extinction, is prominent in the case of small, distant volcanic islets, but on the large islands virtually no loss of endemic species has so far occurred. The same is not true for the non-endemic element of the floras, however. In view of expanding tourism and shifting economy, measures for the conservation of island floras are necessary, but if designed intelligently and taken immediately they can still achieve saving virtually the whole floristic diversity at reasonable cost. It is important that they should include provision for encouraging and supporting research on threatened plants and their natural biota.