A preliminary survey of epiphytes in some tree canopies in Zambia and the Democratic Republic of Congo

The vertical distribution of the density and richness of vascular and nonvascular epiphytes on some mature trees was studied in two 1 km² plots in Miombo Woodland in Zambia (n = 20) and the Democratic Republic of Congo (D.R.C.) (n = 20). The aim was to assess the diversity of arboreal epiphytes and to investigate general distribution patterns of epiphytes along some individual mature phorophytes. Species richness was low on both sampling sites (24 in D.R.C. and nineteen in Zambia) with Orchidaceae being the richest family. Epiphyte density for both sampling plots was high with 92% of the available surface area being occupied. Lichens showed the highest density of 67.2% followed by moss 18.4%, orchids 7.9% and ferns 6.5%. Species richness and density showed a clear zonation within the canopy. Richness and density peaked in the upper and mid-canopy and was positively correlated with available surface area, branch aspect and to some extent bark pH, but not with bark texture. This study demonstrated that tree canopies can harbour a diversity of epiphyte species, and the findings constitute baseline information in such environments.