Diversity of Vascular Epiphytes in Chilimo Forest, West Shoa Zone, Ethiopia
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Date
2019-08-07
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Addis Ababa University
Abstract
This study was conducted to investigate the diversity of vascular epiphytes in Chilimo forest, in Dendi woreda, west shoa zone, Ethiopia at altitude of 2000 – 3288m. Systematic sampling method was employed during data collection. Thirty four sample plots (20x20m) were laid and 400m between transect. All vascular epiphyte species found in each plot were recorded, collected, pressed and identified. A total of eighteen species of vascular epiphytes belonging to seven families were recorded from seventeen host (phorophyte) species in the study area. Orchidaceae, Polypodiaceae and Aspleniaceae are dominant from the families of vascular epiphytes in the study area. Each phorophyte zones(classes) harbored considerable number of epiphyte species, 7 species in basal zone, 10 species in trunk zone and 12 species in canopy zone. The diversity of vascular epiphyte was influenced by phorophyte and diversity increases from base to canopy. More DBH host tree carries more epiphyte. Tree bark texture has an effect on diversity of epiphytes (rough bark texture of the phorophytes has more support epiphyte than smooth barked). Rough bark texture of the phorophytes has high water retention capacity and is more convenient for vascular epiphyte species establishment than smooth ones. Increasing altitudes, decrease diversity of epiphyte due to moisture and go from lower altitude to higher altitude sparsely of forest increases. The main reason for decrease in number of epiphytes towards higher altitudes could be attributed to the low density of the forest trees, which resulted in the availability of suitable host trees (phorophyte) on which the epiphytes grew. As a result of this condition of the forest at higher altitudes, the species richness and abundance of associated epiphytes was limited. Most epiphyte was not host specific. The larger and older trees of the same offer more surface than small trees and also have been available for a longer time than younger hosts for epiphyte colonization. The changing forest structure and tree species composition at increasing altitude provide different quantities and qualities of substrate to epiphytes that resulted in decreasing number of epiphyte species with increasing elevation. Generally, the species diversity of vascular epiphytes is greatly influenced by the phorophyte biophysical factors, such as vertical gradient on individual host plants, host size, bark texture and elevation.
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Keywords
Chilimo Forest, Diversity, Phorophyte, Vascular Epiphyte