Species richness and origin of the bryophyte flora of the Colombian Andes

Based on data from the ECOANDES project, a phytogeographical analysis has been made of the bryophyte flora along the wet, foggy western slope (1000-4500 m) and the drier eastern slope (500-4500 m) of the Colombian Central Cordillera at the ‘Barque de los Nevados’. Species richness increases with altitude to the upper montane forest, which holds the largest diversity. Liverworts outnumber mosses in the upper submontane and montane forests on the western slope, but elsewhere, in drier environments, their number is lower and falls to below that of mosses. Furthermore, it appears that at lower altitudes, below 3000 m, wide-ranging tropical species prevail whereas narrowranging tropical species (andean and endemic element) and species of temperate origin are more common at higher altitudes. Temperate species are relatively few, however, and attain less than 10% in the upper montane forest and about 20% in the paramo. They should have arrived in Colombia in the last 5 million years after the upheaval of the cordilleras.