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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/63

Keywords: Disturbance
Bark pH
Humus pH
Date Added: 4-Sep-2007
Abstract: The Ecology and Diversity of vascular epiphytes were studied in Harenna Afromontane Forest in southeastern Ethiopia at an altitude of 2000 -3000m. Fifty-five species of vascular epiphytes (i.e.22 holoeiphytes, 3 hemiepiphytes and 30 opportunistic/humus/ epiphytes) were recorded. At all altitudinal levels, pteridophytes were the species rich group. The Shannon-Weiner index (H/ = 1.62) of alpha diversity of the epiphyte community in the study area is low. The species diversity of vascular epiphyte is greatly influenced by the host tree biophysical factors, such as vertical gradient of host tree and size as well as the altitude. The regression correlation test showed that the number of species of vascular epiphytes and the size of host tree are positively correlated (R2 = 0.34, p = 0.0001) but non-linear correlation exists between the species number and bark and humus pH. The altitudinal distribution of species of epiphytes was higher towards the lower altitudes (for holoepiphytes and hemiepiphytes) but humus/edaphic epiphytes don’t exhibit clear pattern of distribution. The altitudinal distribution of epiphytes may be influenced by altitudinal factors like temperature and moisture. The vertical distribution of vascular epiphytes (holoepiphytes and hemiepiphytes) along the vertical gradient of the host trees indicated that most species were localized at the intermediate height, except humus epiphytes, which are mostly restricted to the base and below first branches of the host trees. The vertical ecological gradients (i.e. solar radiation and humidity differences from the forest floor to the canopy) may be relevant for the distribution of epiphyte floras. Majority of the species of epiphyte occurred in a wider range of both humus and bark pH (pH = 5.0 - 6.0 for bark and pH = 6.0 to 7.0 for humus) but few species were restricted to narrow range of pH. However, the pH values of humus and the barks utilized by specific species of vascular epiphytes were almost corresponds to each other. The host tree preference of vascular epiphytes was exhibited by few species such as Aerangis brachycarpa, hosted on Vernonia amygdalina and Liparis deistelii, on Schefflera volkensii and Erythrina brucei.
Description: A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Requirement for the Degree of Master of Science in Biology
URI: http://hdl.handle.net/123456789/63
Appears in:Thesis - Biology

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