Growth Performance of Three Indigenous and one Endemic Tree Species of Ethiopia on A Degraded Site in Central-West Ethiopia
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Date
2007-03
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Addis Ababa University
Abstract
comparative studies on growth performance of three indigenous and one
endemic tree species of Ethiopia, viz. Cordia africana Lam., Croton
macrostachyus (Hochst Ex Del.), Podocarpus falcatus (Thunb.) Mirb. and
Millettia ferruginea (Hochst.) Baker were conducted over a period of 8
months. The study was carried out within the landholdings of the Center for
Indigenous Trees Propagation and Biodiversity Development at Tulu-Korma,
about 48 km west of Addis Ababa. Tree seedlings of 88 C. africana, 348 C.
macrostachyus, 256 P. falcatus and 303 M. ferruginea were planted on an
area of 7,682 square meters five months before the start of this study. Each
seedling was assigned a random numerical code for further follow-up
studies. Watering, mulching, adding manure, and prevention measures
from herbivore damage and weeding were handled by workers of the Center.
Data on height and survival percentage were collected every 45 days (in 6-
rounds, including data collected at time 0). Root collar diameter
measurements of each coded tree were taken along with the last height
measurements. Analyses of variance and Tukey’s HSD tests were employed
to assess the results at p=0.05. Data taken on young trees height were also
used for plotting the relative growth rate for height measurements following
previously adopted procedures. The analyses showed significant differences
in growth changes of the tree species studied. Overall relative growth rate in
height (RGRH) of M. ferruginea was found to be the highest, attaining a
value of 0.0045. C. macrostachyus and C. africana stood second and third,
with RGRH values of 0.0036 and 0.0035, respectively. There was no
significant difference between the relative growth rates of C. africana and C.
macrostachyus. P. falcatus had the lowest relative growth rate value of,
0.0028. Of the four indigenous tree species, M. ferruginea attained the
maximum overall change in mean height of 35.3 cm. Its root collar diameter
value ranked second (1.44 cm) next to C. africana (2.23 cm). The survival
percentage was very high in all the four species, ranging between 98.86 and
100 %. Comparison of the major soil properties of the study site indicated
that the area is well below the average values, with total nitrogen of 0.1%
compared to the standard average value of 0.2-0.5%; organic carbon of
1.2%, compared to the standard average value of 4-10%; and available
phosphorus of 2.3 ppm, compared to the standard average value of 14-19
ppm. The only soil parameter that fell within the normal range was pH (6.0).
This work concludes that, despite the poor nutrient status of the site,
growth performance and survival percentage of the four indigenous tree
species were reasonably good, indicating the potential of indigenous trees to
grow on degraded sites provided that intensive management, along with
provision of water during the hot, dry season are maintained.
Key words: Tulu-Korma, survival percentage, root collar diameter, growth
performance, degraded site
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Keywords
Tulu-Korma, survival percentage, root collar diameter, growth performance, degraded site