Growth Performance of two Evergreens and Three Deciduous Indigenous Trees of Ethiopia on Degraded Land at Tulu Korma

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2007-06

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Addis Ababa University

Abstract

A study was conducted on young trees of Prunus africana (Hook. f.) Kalkman, Podocarpus falcatus (Thunb.) Mirb., Millettia ferruginea (Hochst.) Baker, Cordia africana Lam., and Croton macrostachyus Del., planted and maintained within the land holdings of the Center for Indigenous Trees Propagation and Biodiversity Development. The Center is located at 47 Km west of Addis Ababa, along the highway to Ambo. From a mixed stand of young trees planted 5 months before the start of this study, 200 seedlings of P. africana, 185 seedlings of each of P. falcatus, C. africana, and M. ferruginea, and 110 plants of C. macrostachyus were randomly selected and tagged with labeled metal tags. These were followed up for 8 months from October 2005 to May 2006 by assessing parameters such as height, diameter growth, survival, relative growth rate, tip dieback and damage by browsers. During the study period, care and management activities such as watering at intervals of 3 days during the dry months, weeding, hoeing the seedlings, mulching, dung application, fencing and guarding were carried out. Guarding was done regularly, but other activities were done when necessary. Data on plant height were collected every 45 days; root collar diameter measurements were done at the end of the experiment; extent of survival and mortality and damage by browsers were inspected every month. Relative growth rates were calculated for the plant height taking the period of time between two successive measurements. Data were subjected to One Way Analysis of Variance (ANOVA) and Tukey’s Honest Significant Difference Test at P = 0.05. Growth performances of all species varied significantly regardless of the similar treatments administered. Consequently, for variables such as height, survival, relative growth rate in plant height, and tip dieback M. ferruginea performed better compared to all the other species; C. africana was good in root collar diameter increase, but ca 31.4% experienced dieback at the tip. Prunus africana was good in height increment, but ca 14.5% of the seedlings was damaged by browsing animals. C. macrostachyus was good in relative growth rate of seedling height, but 6.4% of the stock was damaged by tip dieback. Podocarpus falcatus was lowest in all the parameters measured, but was very good in terms of percentage survival. Overall, seedlings survival of the studied species wassignificantly higher during the period of rainfall and months of well-watering than during the dry and months less-watering. Soil analysis of the study site yielded a value of 1.3 ppm for available P, 0.071% of total N, and 1.6% of organic C. The values for available P and total N were below the standard minimum values, while that for organic C was somewhat marginal, thus warranting the classification of the site as degraded.

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Biology

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