Diversity, life strategies, origins and distribution of tropical inserlberg bryophytes

Abstract

THE BRYOPHYTE FLORA OF INSELBERGS IN IVORY COAST AND ZIMBALWE CONSISTS OF 31 AND 25 SPECIES, RESPECTIVELY. EIGHT SPECIES, SEVEN GENERA AND THREE FAMILIES ARE COMMON ON INSELBERGS IN BOTH COUNTRIES. THE NUMBER OF SPECIES OF BRYOPHYTES ON INSELBERGS IS NOT CORRELATED WITH THEIR SIZE OR THEIR ELEVATION. IN IVORY COAST, MORE BRYOPHYTE SPECIES ARE FOUND ON INSELBERGS IN SAVANNA REGIONS THAN IN RAIN FOREST REGIONS. IN IVORY COAST AND ZIMBABWE, ROUGHLY 30% OF THE BRYOPHYTES ARE PANTROPICAL, TROPICAL AFRICAN AND SUDANO-ZAMBESIAN IN DISTRIBUTION; 12-13% ARE COSMOPOLITAN SPECIES. THE APPARENT LACK OF SEXUAL AND VEGETATIVE PROPAGATION IS CONSPICUOUS IN INSELBERG MOSSES AS IS THE SMALL PERCENTAGE OF SPECIES THAT SHOW SPECIALIZED ANATOMICAL OR MORPHOLOGIC ADAPTTIONS TO THIS EXTREME HABITAT. COMPARED TO FLOWERING PLANTS, INSELBERG BRYOPHYTES BELONG TO LARGER PHYTOGEOGRAPHICAL ELEMENT AND HAVE NO ENDEMIC SPECIES. IN FLOWERING PLANTS AND IN BRYOPHYTES MOST SPECIES BELONG TO A FEW FAMILIES AND INSELBERGS IN SAVANNA REGIONS ARE RICHER IN SPECIES THAN THOSE IN RAIN FOREST REGIONS. WHEREAS INSELBERG PHANEROGAMS ARE MOSTLY ANEMO OR ZOOCHORUS, INSELBERG MOSSES ARE "ACHOR" SHOWING PREDOMINANTLY NEITHER SEXUAL NOR VEGETATIVE MEANS OF PROPAGATION.