BIOGEOGRAPHY AND CHOROLOGY OF THE BRYOPHY TES OF THE SIERRA DE GREDOS

The bryoflora of five valleys in the northern slope of the Sierra de G redos (Spain), ranging from 1300 m to 2000 m, has been studied. The hi ghest species richness has been found between 1700 m and 1800 m, becau se in this interval, the studied localities also showed a larger numbe r of different habitats. The most abundant chorological elements were boreal (35% of the species), temperate (28%) and oceanic (26%). Compar isons with other ranges of the Iberian Peninsula provide some insights about the main factors contributing to this pattern: the atlantic inf luence and the high altitude of the studied mountains. The most releva nt species found are Jungermannia jenseniana, a very rare liverwort in the Iberian Peninsula, and two Iberian endemics: Brachythecium diecki i and Racomitrium hespericum.