Epiphyte communities of tropical montane rain forests in the northern Andes I. Lower montane communities
Wolf, Jan H. D.
The climate of forests along an altitudinal transect in the Central Cordillera of Colombia has been documented and their epiphytic vegetation described, using the Braun-Blanquet approach in phytosociology. With help of the classification computer program TWINSPAN, 528 relevés have been grouped in 22 communities. Despite a considerable amount of heterogeneity between relevés, the computer analysis revealed 4 main groups of communities, which proved to be altitudinally separated. In this paper, the first out of a series of two, the communities of a lowland forest and of the Lower Montane Rain forest are described. The recognized communities could be related to position within the host tree. It appeared that several cryptogamic epiphytic species of the Colombian Lower Montane Rain forests occur in the warmer Lowland Rain forest of Guyana in more exposed habitats which receive more radiation energy. These field observations corroborate the results of experimental laboratory studies on the tropical lichen Dictyonema glabratum and suggest that these species require more radiation energy at higher temperatures to attain a positive net photosynthesis.