The distribution of epiphyte growth-forms in the canopy of a Colombian cloud-forest

Cloud forests are known for their abundance in epiphytes. The growth-form composition of the epiphytic vegetation in the crowns of two tree-species in an upper-andean forest in Colombia is described. Bryophytes formed the bulk of the living epiphytic biomass, with tall turfs and smooth mats (sensu Richards 1984) as commonest growth-forms. Vascular plants and lichens were subordinate to bryophytes. Along the canopy-branches a clear sequence of growth-forms could be demonstrated. Analysis of this gradient by Detrended Correspondence Analysis (DCA), Two Way Indicator Species Analysis (TWINSPAN) and calculation of association-indices between growth-forms revealed two basic groups. One group is typical for the inner canopy, another for the outer canopy. An important determinant of the growth-form composition was the phorophyte species. The vegetational gradient was interpreted in terms of gradual changes in microclimatological factors, water- and nutrient availability and substratumage.