An Ecological Study o,f The Grassland Vegetation in Some Parts of Gojam.
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Date
1991-01
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Addis Ababa University
Abstract
A study of the grassland vegetation in Gojam was made in October, 1989. 148
stands from 30 sites, were systematically sampled. A total of 115 species of
vascular plants were recorded and cover-abundance for each species was
estimated. The most commonly encountered species are members of the families
Poaceae, Asteraceae, Cyperaceae and Fabaceae in that order. The vegetation
data matrix was summarized by minimum variance and complete-linkage clustering
techniques. Two major groups were identified by minimum variance clustering,
i.e., one containing most of the quadrats from the wet sites and the other
consisting most quadrats from the drier sites. Nine groups were identified by
complete-linkage. These groups show some variations in management and drainage
conditions and also show variability in species composition and diversity. In
the protected and enclosed sites for afforestation, the dominant grasses are
Andropogon abyss in icus R.Br ex Fresen and Hyparrhenia spp. while in the grazed
sites Pennisetum sphacelatum Th. Dar and Schinz, Eleusfne floccifolia (Forsk.)
Spreng., Plantago lanceolata L., Eragrostis tenuifolia A. Rich and Cynodon
dactylon (L.) Pers. are the species which have higher cover abundance values.
In the wet sites which are protected during the rainy season Andropogon
chrysostachys Steud, Pennisetum glabrum Steud., Eragrostis botryodes Clayton.,
Uebelinia sp. Pycreus atronervatus (BoCk) C.B.Cl and P. flavesence L. are the
dominant species. In the wet and grazed sites the common species are
Echinocloa haploclada Stapf. , Arthraxon micans (Nees) Hochst, Paspallum
commersonii Lam. and Hygrophilla auriculata (Schum) Heine. The clusters
obtained were compared based on the mean values of the environmental factors
using analysis of variance and t-test. The intensively grazed and protected
sites show differences in the mean values of per cent organic carbon and total
nitrogen content. PH, conduct i v ity and cat i on content of the so il showed
positive correlation between them selves.
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Biology