Browsing by Author "Tafa, Abuna"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Diversity of Vascular Epiphytes Along Disturbance Gradient in Yayu Forest, Southwest Oromia, Ethiopia
    (Addis Ababa University, 2010-07) Tafa, Abuna; Nemomissa, Sileshi (Professor); Woldemariam, Tadesse (PhD)
    The change in species diversity and composition of vascular epiphytes along disturbance gradient was studied in Yayu forest of southwest Ethiopia. Systematic sampling method was employed in data collection with a line transect was laid out along disturbance gradient of the forest. Based on their increasing level of disturbance, the forest was divided into three management zones: natural forest (core zone), semi-forest coffee production system (buffer zone) and agricultural matrices (transition zone) respectively. A total of thirty-six species of vascular epiphytes were recorded from thirty-five host (phorophyte) species in the study area. Each forest zone harbored considerable number of epiphyte species, 31 species in core zone, 32 species in buffer zone and 24 species in transition zone. This indicates the existence of changes of species diversity along disturbance gradient of the forest due to anthropogenic disturbance. The species diversity of vascular epiphytes is also greatly influenced by the phorophyte biophysical factors, such as vertical gradient on individual host plants, host size, bark texture and elevation. Thus, vertical distribution of vascular epiphytes indicated that species diversity increases from phorophyte base to the canopy. 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. Rough bark texture of the phorophytes has high water retention capacity and is more convenient for vascular epiphyte species establishment than smooth ones. 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. Furthermore, host preference of vascular epiphytes was apparently exhibited by few species such as: Angraecopsis infundibulum, Polystachya cultriformis, Vittaria volkensii, Chlorophytum comosum and Coleochloa abyssinica. Key words: Disturbance Gradient, Diversity, Phorophyte, Species composition, Species turnover, Vascular Epiphyte, Yayu Forest.