The Mannio-Exormothecetum pustulosae ass. nov., a xerophytic bryophyte community from Madeira and the Canary Islands/Macaronesia
Kürschner, Harald; Fontinha, Susana; Sim-Sim, Manuela; Frey, Wolfgang
A phytosociological analysis of the xerophytic bryophyte communities of the Macaronesian Islands (Madeira, Porto Santo, Deserta Grande, Gran Canaria, Tenerife) reveals a distinct community, the Mannio androgynae-Exormothecetum pustulosae new to science. It is typical for the open, seasonally very dry and sunny sites in the understorey of the succulent scrub (Kleinio-Euphorbietea canariensis) of the infracanarian belt. Here it is frequent in temporarily moist depressions and flats, on earthy banks and sites amongst rock boulders where an additional layer of fine earth and surplus water is available. On Madeira Island, a more ruderalized development can be observed under increasing anthropogenic influence, classified as oedipodielletosum australis subassociation.The life form and life strategy analyses show clearly that the new association is composed of mat-forming marchantioid and riccioid liverworts and short turf-forming acrocarpous mosses, following an annual and short-lived shuttle species strategy with a high sexual reproductive effort. Perennial stayers occur, however, are of minor significance. Colonists, which mostly consist of pioneering species, mainly are restricted to the oedipodielletosum australis which grows under more unstable and ruderalized site conditions. Outstanding in the community is Oedipodiella australis. This South African species extends its distribution to Southwest Europe (France, Spain and Macaronesia-Madeira Islands) (Thorvenot 2000, Van Dort & Viewkoop 2003) and is a further example of the geophyte life strategy, characterized by persistent, subterranean, rhizom-like main axis and numerous branches, which are formed during favourable seasons.