Browsing by Author "Maryo, Melesse"

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    Biological and Ecological Studies on Acacia Drepanolobium Harms Ex Sjöstedt in Borana Zone of Oromiya Regional State, Ethiopia
    (Addis Ababa University, 2003-06) Maryo, Melesse; Nemomissa, Sileshi (PhD); Kelbessa, Ensermu (PhD)
    The biological and ecological studies of A. drepanolobium: the floristic composition in A. drepanolobium wooded grassland, soil properties, seed production, seed dispersal, soil seed bank, percent seed germination at different treatments, capacity of coppicing , and its interactions (symbiosis) with ants, insects and microbes were investigated in four A. drepanolobium wooded grassland sites in Negele Borana , Oromiya Regional State, S. Ethiopia. The results indicated that in A. drepanolobium wooded grassland 114 plant species were identified. Of these 70.2 %, 23.7% and 6.1% were herbs, trees/shrubs and climbers respectively. More over, 33.3 % were forage species whereas 14.4% and 2.6% had socioeconomic and medicinal importance respectively. Asteraceae, Fabaceae and Poaceae have constituted 36 % of the total number of species. The number of species was found to be smaller than previous studies on non- A. drepanolobium wooded grassland of the study area. This may suggest the impact of bush encroachment by A. drepanolobium, which had a mean density of 1798 plants/ hectare with a large number of individuals at the younger stage. The soils studied had higher proportion of clay (> 30 %) with properties that favor the growth of most plant species. An average of 2417 ± 23 (X ± SE) seed production per plant was encountered, and only 1 ± 0.4 (X ± SE) trees bore seeds in average per plot. Seeds are mainly dispersed by wind. 267 seeds (8.3 ± 2.6 seeds /m 2) were found only at the litter layer and none in mineral soil layer. There was statistically significant difference in percent germination among treatments [F (5, 17), P < 0.05]. Fast rate and higher percent germination was achieved by scarification treatments whereas dry heat treatment (90 oC) and moist heat (98 oC for greater than 30 minutes) resulted in almost all mold outgrowths after a week’s period. Tukey’s HSD indicated that moist heat treatments didn’t improve the percentage germination. High percent germination of a control experiment within week’s time may suggest the absence of pronounced seed dormancy in the study species. There is no statistically significant difference among stumping treatments both in number and in height of coppice but the coppice number and height increased down to a tree height (soil surface). Four A. drepanolobium occupant ant species (3 Crematogaster and 1 Tetraponera species) were identified. However, a black cotton soil habitat hosted only 2 Crematogaster species. Although each tree was occupied by a single ant species, Crematogaster mimosae occupied the largest proportion (85%) of seed bearing trees. The mutualistic association of Crematogaster nigriceps is doubtful because this species sterilizes flower buds and new shoots. Two seed feeding bruchid beetles (Callosobruchus maculatus and Acanthoscelides obtectus) were identified and found to reduce the reproductive vigor of the study species by mass predation of its seeds. A. drepanolobium was found to be nodulated by slow growing rhizobia called Bradyrhizobium species. There was no statistically significant difference in nodulation status between two soils (t at 24 df = -1.22 and P=0.268). The mean nodule number and weight were 4.93 ± 0.6 and 0.00381 ± 0.0008 (X ± SE) in clay soils respectively. Reduction in nodulation may be due to 1) richness of clay soil in mineral elements including nitrogen 2) absence of adequate aeration 3) missing of some nutrients elements such as molybdenum and 4) Slowness of the fixer species. From the socio-economic view point, 50% of informants declared the importance of A. drepanolobium, and the rest expressed their hatred for its bush encroachment impacts on their surrounding. However, from the present study , it can be suggested that sterilization of flower buds and young shoots by Crematogaster nigriceps ants, low soil seed bank, seed predation by bruchid beetles and low recruitment being the limiting factors, further expansion of bush encroachment by A. drepanolobium can be managed through integrated bush management systems such as reducing cultivation of dry season grazing areas, encouraging traditional rangeland management systems and applying proper land use policy, reducing excess livestock, stumping late in rainy seasons and periodic burning though complete recovery of the previous range condition is a difficult task. Key words: A. drepanolobium, bush encroachment, seed characteristics, Crematogaster, bruchid beetles.
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    Enset- Based Agrobiodiversity in the Agricultural Landscape of Kambatta Tembaro (KT), Southern Ethiopia
    (Addis Ababa, Ethiopia, 2013-06) Maryo, Melesse; Bekele, Tamrat (PhD)
    The managem~nt of agrobiodiversity (AB) by farmers buttresses sustainable food security and continuous ecosystem services against the predicted future global environmental change. However, the loss of traditional knowledge on local landraces. and breeds, inadequate information on AB distribution, and the focus on improved varieties are becoming threats for the long-term conservation of AB. The current study focuses on agrobiodiversity of enset- based agricultural landscape of KT, southern Ethiopia. The agroclimate of the areas was used for selecting a total of 12 study sites (farmscapes). To understand the roles of the socio-economic conditions on AB, 180 households (HHs) were selected based on the wealt~ status. Environmental data such as slope and elevation were recorded for each sampling sites. The area share of the crop as well as woody species was measured, and the species were inventoried. Standard ethnobotanical methods were used to collect information on the uses of these plant species. The data analyses were carried out by Cr4NOCO for Windows ver. 4.52, R program 2.14.0, Minitab ver 15, and SAS ver. 8.02. A total of 371 plant species were recorded whereby crop ' are 92 and woody pecie are 186. A total of 170 medicinal plant species that are helpful in the primary health care of the human and the livestock are reported. Seventeen plant species endemic to Ethiopia were identified, of which thirteen are medicinal plants. Years of farming, livestock holding, and distance to market influenced the number of crop species significantly. There are 111 landraces of enset (Ensete ventricosum) recorded from the study area. The number of landraces increases with increase in the farmland size and the elevation. The slope, age of farmland, area of the woodlot, and available HH labour influence the woody species richness. One exotic tree species, Eucalyptus camaldulensis was identified as the most important woody species. Finally, it is recommendable to train extension agents on the areas of AB maintenance so that they would assist farmers effectively. Moreover, avoiding extensive plaptation of Eucalyptus on crop fields may contribute to the long-term persistence of AB of the study area.