Browsing by Author "Asgedom, Yemane"

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    An Ecological Study o,f The Grassland Vegetation in Some Parts of Gojam.
    (Addis Ababa University, 1991-01) Asgedom, Yemane; Woldu, Zerihun (PhD)
    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.