Browsing by Author "Nigatu, Lisanework"

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    An Ecological Study of The Vegetation of the Ravenna Forest
    (Addis Ababa University, 1987-06) Nigatu, Lisanework; Tadesse, Kesfin (PhD)
    An ecological study of the vegetation of the Harenna forest was performed from April 1986 to October 1986. Data on the vegetation and environmental factos were collected, i.e. enumeration of tree and shrub species, an estimate of cover abundance value for herbs, epiphytes and lianes, alti~ tude, edaphic factors and topography. The program GROUPAGE \'las used to summarlze -the vef,eta-tion data. The program CHECK \'las employed to analyse species diversity. Five homogeneous clusters of vegetation were re~ cognized using the presence-absence and quantitative data. The clusters obtained were compared for the mean values of the environmental factors using the statistic t-test. The highest number of significant contrasts among the clusters were observed to result from variation in altitude. Analysis of species diversity showed that with increasing al ti tude, tree and shUl'b species decrease \>I11ile herbaceous species, epiphytes and lianes increase in number. As a result, in the area of the Harenna forest, the main vegetation gradient is caused by differences in altitude associated \'lith variation in moisture. The moisture gradient is accompanied by gradients in soil physical and chemical properties and topography.
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    Ecological Studies of Plantations In Some Parts of Ethiopia, With Special Regard to Ecological Effects of the Use of Eucalyptus SPP.
    (Addis Ababa, Ethiopia, 1994-04) Nigatu, Lisanework; Friis, Ib. (Professor)
    Ethiopia has a long trad ition of es ta blishing planl31ion trees. EllcalYPlllS plantatio ns. especially. ha ve been developed in Ih is country si n ce Ihe beginning of th is ce ntu r y. This stud y presents inf ormati on on thc undergrowth vegc tatio n cha ra cte ri s ti cs. soil co ndit io ns l nd nutrient cycling in established plantati o ns and n:ltural fo rests in Ethi opia. combined with bioassays o f ge rmin atio n, g rowth a nd nutri ent uptake o f pla n ts. Vegctat ion and environmen tal dlt3 we rc collec ted fr om ninet y-two p l::tnt3ti on and natural fo rest sites in wC51. nonh-cast. sou th. lnd ccn n31 regions of Ethio pia. Fou r permanent pl o ts werc cSllblishcd in three planl:lIion lnd l n:lIur:.ll mo nl:lnc forest stands fo r long term 3ssessments of nutrient cycling 3nd soi l fertility. So ils collected f rom under plant3tions and 3 n3 tu ell f o rcs!, a nd aqueous 1e3 f e: