ECOLOGY OF FOLIICOLOUS LICHENS AT THE BOTARRAMA TRAIL (COSTA-RICA), ANEOTROPICAL RAIN-FOREST - III - PHOROPHYTE RANGES AND PATTERNS OF PHOROPHYTE PREFERENCES

Phorophyte ranges and patterns of phorophyte preferences in foliicolou s lichens were studied by clustering of individual phorophytes on the basis of their lichen species composition. Foliicolous Lichens exhibit broad phorophyte ranges and low specifity. Phorophytes of the same sp ecies only cluster together as long as their leaf characters are suffi ciently different from each other, but the number of discriminating fo liicolous lichens is low. A distinct grouping effect of phorophytes wi th similar foliicolous lichen diversity indicates that phorophyte pref erences are quantitative rather than qualitative, resulting in differe nt diversity stages rather than different species composition. These d iversity stages can be interpreted as different stages of succession. Species composition is strongly affected by microclimatic conditions, in particular relative light intensity. Two large groups of foliicolou s lichen species can be found discriminating between shady understory and Light gap phorophytes, with Arthoniaceae, Opegraphaceae and Tricho theliaceae being typical for shady understory phorophytes, and Gomphil laceae and Ectolechiaceae dominant on Light gap phorophytes.