Flora and Biogeography

Abstract

In the first part of this chapter, the history of botanical exploration is explored. The most important floristic work to appear in recent times is the Ethnoflora of the Soqotra Archipelago, outlining 828 species of vascular plants that have been recorded from the area. A striking feature is the high proportion (37%) of endemics. Palaeoendemics appear to be rather poorly represented, and recent molecular phylogenetic studies are beginning to emphasise the role of neoendemism in shaping the flora. The vascular flora has its closest affinities to the adjacent regions of the Horn of Africa and southern Arabia, but distinct links exist to other geographical areas much further afield. Recent evidence also suggests that long-distance dispersal of ancestral species has contributed substantially to the development of the present-day flora, as demonstrated by various examples. It can be assumed that with the arrival of the first settlers on the islands, many native plant communities have been subject to pronounced changes in species composition, and examples of the two major groups that have benefited from human impact, “invaders” and “colonisers”, are given. Twenty-six species of fern are known from the archipelago, with only one endemic. Fairly detailed overviews now exist of the bryophyte and lichen flora. The biogeography of these two groups is of considerable interest, as they are quite ancient in geological terms and occur in comparable habitats throughout the world.