Browsing by Author "Lemenih, M."

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Comparative assessment of soil and nutrient losses from three land uses in the central highlands of Ethiopia
(Academic journals, 2017) Jaleta, D.; Mbilinyi, B. P.; Mahoo, H. F.; Lemenih, M.
Land use/land cover change drive changes in several ecosystem processes over short and long terms. In Ethiopia, the main land use/land cover change involves conversion of natural ecosystem into cultivated land. However, a recent change also involves conversion of cultivated and gra zing land into Eucalyptus woodlots. This study was conducted to analyse the effects of such land use/land cover change on soil and nutrient losses. Three land use/ land cove r types (cultivated land, grassland and Eucalyptus woodlot) were selected for a comparative assessment. A total of twelve runoff plots, each with 43.3 m2 area and with four replications, were installed. Rainfall depth, runoff volume and sediment samples (500 ml) were collected from each plots every morning and evening for 91 days (from 4th July to 2nd October, 2015) in the main rainy season. The sediment samples for ten consecutive days were stored in separate containers and composite sediment concentration samples were weighed after being filtered and oven dried for 24 hours at 105o c. From the samples taken at the end of the rainy season, separate composite a sample before filtration of one litre was analysed in the laboratory for nutrient losses. The effect of land use/land cover on soil and nutrients losses was statistically tested using analysis of variance. The study found that soil loss significantly differed between the land use /land cover types. Soil loss from cultivated land (16.8 ton/ha) was significantly higher than loss from grassland (7 ton/ha) and Eucalyptus stand (8.1 ton/ha). The soil and nutrient losses were positively correlated with runoff volume. There was higher nutrient (N and P) loss from cultivated land than grassland and Eucalyptus. From the results, it can be concluded that soil and nutrients losses are above tolerable limit, and perennial land covers including Eucalyptus stand reduce soil and nutrient losses significantly. This re-affirms the multi-purpose nature of Eucalyptus not only for socioeconomic benefit but also for soil erosion control when planted in appropriate locations
Effect of Eucalyptus expansion on surface runoff in the central highlands of Ethiopia
(SpringerOpen., 2017) Jaleta, D.; Mbilinyi., B. P.; Mahoo, H. F.; Lemenih, M.
Over the last century, Eucalyptus has rapidly expanded across the globe. It has become the most planted tree species. Environmentalists fear this for the perceived negative eco-hydrological impact. Foresters and wood industries support its expansion looking at its socio-economic benefits. Ethiopia is one of the countries where Eucalyptus dominates forest development gains in the last century. The main purpose of this review is to evaluate the expansion, benefit and challenges of Eucalyptus in Ethiopia. Eucalyptus was introduced to Africa, and Ethiopia, around the end of the 19th century, in 1890s. Since then it has continued to expand to cover wider geographic areas within Ethiopia: highland and lowland. It is providing multiple purposes, economic and social, for millions of households in urban and rural areas. It has substituted effectively some of the natural forest’s functions, principally in wood supply; hence this way it has contributed to reducing pressure and in slowing down deforestation. Yet Eucalyptus sustained blame for ecosystem water and soil nutrient drains, and allelopathic effect to suppress native flora growth. Studies on these aspects of the genus are inconclusive. Some argue the extravagant use of water and nutrient, while others argue otherwise. There are studies that show water and nutrient use of Eucalyptus is based on availability: for instance, dry season and wet season uses are not the same. The most known about Eucalyptus is its high nutrient and water use efficiency. Therefore, when evaluated on per volume of water, nutrient and land allocated for biomass production, Eucalyptus will provide the highest biomass return. This may make it the preferred species. The paper concludes that the development of Eucalyptus forestry is crucial in narrowing the gap between forest product demand and supply in the current context of Ethiopia and most African countries, but such development should be managed with proper silviculture: Planted in the right site and tended properly to optimize its positive values and reduce possible negative effects.