Ecological Study of Shrubland Vegetation along the Escarpments between Addis Alem and Wolenkomi, West Shewa, Oromoia National Regional State
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Date
2012-06
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Addis Ababa University
Abstract
The study was conducted in Oromia National Regional State, West Shewa Zone, along
escarpments between Addis Alem and Wolenkomi towns with objective of investigating
ecology of shrubland vegetation of the area. Vegetation data were collected from 50
quadrats which were systematically laid. Quaqrats of 20 m x 20 m (400 m2) were laid for
woody species (shrub/trees). For the collection of herbaceous species, subplots of 1 m x 1
m at the four corners and the center of the large quadrat were established. Cover
abundance value of all the species was estimated in the field, and then later converted to
the Braun-Blanquet 1-9 scale as modified by van der Maarel (1979). One hundred and one
plant species were collected and identified there were grouped into 88 genera and 48
families. Hierarchical cluster analysis was employed to analyze community type. Four plant
community types: Euphorbia ampliphylla -Halleria lucida, Dovyalis abyssinica- Ficus sur,
Caparris tomentosa - Maesa lanceolata and Rubus apetalus - Indigofera spicata were
identified. Shannon - Wiener index of species diversity was applied in order to evaluate
species diversity and richness. Accordingly, community type 2 is the highest in diversity
(3.7 diversity index) while community type 1 is the lowest in diversity (2.88 diversity
index). Height and diameter at breast height (DBH) of all woody species taller than 2 m and
thicker than 2 cm were measured in the field. The overall density of tree or shrub species
which have DBH >2cm was 874 individual/ha. Based on the computation of Importance
Value Index, Croton macrostachyus, Carissa spinarum, Olea europaea subsp. cuspidata,
Pterolobium stellatum and Acacia abyssinica, were identified to be the dominant woody
species of the area.
Key words/phrases: Addis Alem and Wolenkomi, ecological study, plant community,
shrubland vegetation, species richness/diversity
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Key words/phrases: Addis Alem and Wolenkomi, ecological study, plant community, shrubland vegetation, species richness/diversity