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Title: Assessment on the Recent Drying-Up of Eucalyptus Species in Selected Areas of the Highland of Arsi and Wollo, Ethiopia
Authors: Demelash, Bekele
Advisors: Mekuria Argaw(Dr.)
Keywords: Arsi
Wollo
Copyright: Oct-2010
Date Added: 12-Jul-2012
Publisher: Addis Ababa University
Abstract: Drying-up of Eucalyptus species is not a common phenomenan in Ethiopia. The objective of this study was to assess the possible causes of the drying-up of the trees of major Eucalyptus plantations in two selected case areas and to make a recommendation for remedial measures. Systematic sampling was employed and 20m×20m quadrats at 100m interval were laid out along transect. In each quadrat vegetation and soil were assessed for biotic & abiotic factors. Among the abiotic factors soil depth, soil texture, bulk density, water holding capacity of the soil, slope, and aspect were assessed. Among the biotic factors soil and root pathology and stand density were assessed. Pearson correlation coefficient was used to compare the strength of the relationship of the parameters with mortality rate of the trees. ANOVA was also used to compare rooting depth of the live and dried trees. Mortality rate of Eucalyptus camaldulensis is negatively correlated with soil depth with a correlation coefficient ( pearson coeff.= -0.8507, P=0.0157) and (Pearson coeff.=-0.9393, P=0.0175) for both case area I and case area II, respectively. There were no correlation between all other soil physical factors and mortality. The rainfall was very much below the average or complete failure of rain (i.e., 0 mm in the months of February & March and 18.1mm in April of 2008) and the temprature went above the average, i.e, 270c for 6 consecutive months. According to litreature such climatic pattern resulted in drying-up in the following year. Root and soil samples test for phytophtora, which is known to cause root rot were assessed and found negative for both the healthy and dried sample trees. On the other hand a comparative disease symptom assessment of the stems of the live and dried trees were made and the result showed that there was no indication of disease. Among the parameters taken only soil depth found to be the likely cause of Eucalyptus drying-up. All the other possible causes assessed didnt correlated significantly. As the result indicated from this study, it can be concluded that shallow soil depth through its effect on moisture availability resulted in Eucalyptus dry-up in the long term.
Description: A thesis submitted to the partial fulfilment of the Msc. degree in Environmental Science
URI: http://hdl.handle.net/123456789/3337
Appears in:Thesis - Environmental Sciences

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