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Ethiopian Highlands (ethiopian + highland)

Distribution by Scientific Domains

Earth and Environmental Science	77%

Selected Abstracts

Species and structural diversity of church forests in a fragmented Ethiopian Highland landscape

JOURNAL OF VEGETATION SCIENCE, Issue 5 2010
Alemayehu Wassie
Abstract Question: Thousands of small isolated forest fragments remain around churches ("church forests") in the almost completely deforested Ethiopian Highlands. We questioned how the forest structure and composition varied with altitude, forest area and human influence. Location: South Gondar, Amhara National Regional State, Northern Ethiopia. Methods: The structure and species composition was assessed for 810 plots in 28 church forests. All woody plants were inventoried, identified and measured (stem diameter) in seven to 56 10 m x 10-m plots per forest. Results: In total, 168 woody species were recorded, of which 160 were indigeneous. The basal area decreased with tree harvest intensity; understorey and middle-storey density (<5 cm DBH trees) decreased with grazing; overstorey density (>5 cm DBH trees) increased with altitude. The dominance of a small set of species increased with altitude and grazing intensity. Species richness decreased with altitude, mainly due to variation in the richness of the overstorey community. Moreover, species richness in the understorey decreased with grazing intensity. Conclusions: We show how tree harvesting intensity, grazing intensity and altitude contribute to observed variations in forest structure, composition and species richness. Species richness was, however, not related to forest area. Our study emphasizes the significant role played by the remaining church forests for conservation of woody plant species in North Ethiopian Highlands, and the need to protect these forests for plant species conservation purposes. [source]

Dynamics of soil erosion rates and controlling factors in the Northern Ethiopian Highlands , towards a sediment budget

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2008
Jan Nyssen
Abstract This paper analyses the factors that control rates and extent of soil erosion processes in the 199 ha May Zegzeg catchment near Hagere Selam in the Tigray Highlands (Northern Ethiopia). This catchment, characterized by high elevations (2100,2650 m a.s.l.) and a subhorizontal structural relief, is typical for the Northern Ethiopian Highlands. Soil loss rates due to various erosion processes, as well as sediment yield rates and rates of sediment deposition within the catchment (essentially induced by recent soil conservation activities), were measured using a range of geomorphological methods. The area-weighted average rate of soil erosion by water in the catchment, measured over four years (1998,2001), is 14·8 t ha,1 y,1, which accounts for 98% of the change in potential energy of the landscape. Considering these soil loss rates by water, 28% is due to gully erosion. Other geomorphic processes, such as tillage erosion and rock fragment displacement by gravity and livestock trampling, are also important, either within certain land units, or for their impact on agricultural productivity. Estimated mean sediment deposition rate within the catchment equals 9·2 t ha,1 y,1. Calculated sediment yield (5·6 t ha,1 y,1) is similar to sediment yield measured in nearby catchments. Seventy-four percent of total soil loss by sheet and rill erosion is trapped in exclosures and behind stone bunds. The anthropogenic factor is dominant in controlling present-day erosion processes in the Northern Ethiopian Highlands. Human activities have led to an overall increase in erosion process intensities, but, through targeted interventions, rural society is now well on the way to control and reverse the degradation processes, as can be demonstrated through the sediment budget. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Species and structural diversity of church forests in a fragmented Ethiopian Highland landscape

Rainfall-discharge relationships for a monsoonal climate in the Ethiopian highlands

HYDROLOGICAL PROCESSES, Issue 7 2008
Ben M. Liu
Abstract This study presents a simple rainfall-discharge analysis for the Andit Tid, Anjeni, and Maybar watersheds of northern Ethiopia. The Soil Conservation Research Programme (SCRP) established monitoring stations in each of these sites during the 1980s, with climate and stream flow measurements being recorded up to the present. To show how these data could be used to provide insight into catchment-level runoff mechanisms, simple linear relationships between effective precipitation and runoff are developed for each watershed, with the conclusion that all three watersheds exhibit consistent hydrologic behaviour after approximately 500 mm of cumulative effective seasonal rainfall has fallen since the beginning of season. After the 500 mm rainfall threshold is reached, approximately 50% of any further precipitation on these watersheds will directly contribute to catchment runoff. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Dietary specialization and climatic-linked variations in extant populations of Ethiopian wolves

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2010
Jorgelina Marino
Abstract Understanding of the biology of rarity is central to the conservation of some endangered species. Rare taxa are often reported to be specialized, but they are usually poorly studied. The Ethiopian wolf (Canis simensis) is endemic to the Ethiopian highlands and in two major populations, Bale and Arsi in the southern range of the species, it preys almost exclusively upon diurnal rodents all year round, mainly molerats Tachyoryctes macrocephalus and common molerats T. splendens, respectively. Where these large rodents are absent or rare, wolves are expected to rely more heavily on nocturnal rats or livestock. Prey remains in 161 scats from five newly studied populations confirmed that wolves are indeed specialist rodent hunters elsewhere, and that their narrow diets are dominated by diurnal Murinae rats (60,83% of prey occurrences). Swamp rats Otomys typus were the main prey, followed by grass rats Arvicanthis abyssinicus. Common molerats, Lophuromys rats and nocturnal Stenocephalemys spp. constituted the variable portion of the diets, and their proportional contributions varied across populations in relation to elevation and latitude. Towards the north, where the climate is drier and human populations more dense, wolves predate more frequently on rat-sized prey, including nocturnal species, with implications for the survival of small populations in the Northern Highlands. Résumé Pour la conservation de certaines espèces en danger, il est essentiel de bien comprendre la biologie de la rareté. On rapporte souvent que des taxons rares sont spécialisés, mais ils sont généralement peu étudiés. Le loup d'Ethiopie Canis simensis est endémique des hauts plateaux éthiopiens et deux populations majeures, Bale et Arsi, dans la partie sud de leur aire de répartition, se nourrissent toute l'année presque exclusivement de petits rongeurs diurnes, surtout des rats-taupes géants Tachyoryctes macrocephalus et, plus communs, des rats taupes des montagnes T. splendens. Là où ces rongeurs sont absents ou rares, on s'attend à ce que les loups se nourrissent davantage de rats nocturnes ou de bétail. Des restes de proies identifiées dans 161 crottes de cinq nouvelles populations étudiées récemment ont confirmé que les loups sont bien, ailleurs, des chasseurs spécialisés en rongeurs et que leur régime alimentaire peu varié est dominé par des Murinae diurnes (60,83% des proies observées). Les rats des marais Otomys typusétaient les proies principales, suivis par les rats des herbes Arvicanthis abyssinicus. Les rats-taupes communs, les rats Lophuromys et les nocturnes Stenocephalemys spp. constituaient des portions variables du menu, et la proportion de leur contribution variait pour les populations en fonction de l'elevation et de la latitude. Vers le nord, là où le climat est plus sec et où la population humaine est plus dense, les loups s'attaquent plus souvent à des proies de la taille des rats, y compris des espèces nocturnes, ce qui a des implications pour la survie des petites populations des hauts plateaux du nord. [source]

Plant species and growth form richness along altitudinal gradients in the southwest Ethiopian highlands

JOURNAL OF VEGETATION SCIENCE, Issue 4 2010
Wana Desalegn
Abstract Questions: Do growth forms and vascular plant richness follow similar patterns along an altitudinal gradient? What are the driving mechanisms that structure richness patterns at the landscape scale? Location: Southwest Ethiopian highlands. Methods: Floristic and environmental data were collected from 74 plots, each covering 400 m2. The plots were distributed along altitudinal gradients. Boosted regression trees were used to derive the patterns of richness distribution along altitudinal gradients. Results: Total vascular plant richness did not show any strong response to altitude. Contrasting patterns of richness were observed for several growth forms. Woody, graminoid and climber species richness showed a unimodal structure. However, each of these morphological groups had a peak of richness at different altitudes: graminoid species attained maximum importance at a lower elevations, followed by climbers and finally woody species at higher elevations. Fern species richness increased monotonically towards higher altitudes, but herbaceous richness had a dented structure at mid-altitudes. Soil sand fraction, silt, slope and organic matter were found to contribute a considerable amount of the predicted variance of richness for total vascular plants and growth forms. Main Conclusions: Hump-shaped species richness patterns were observed for several growth forms. A mid-altitudinal richness peak was the result of a combination of climate-related water,energy dynamics, species,area relationships and local environmental factors, which have direct effects on plant physiological performance. However, altitude represents the composite gradient of several environmental variables that were interrelated. Thus, considering multiple gradients would provide a better picture of richness and the potential mechanisms responsible for the distribution of biodiversity in high-mountain regions of the tropics. [source]