This study was conducted on Boda Forest in West Showa Zone, Oromia National Regional State, west Ethiopia with the objective of determining the floristic composition, species diversity and the vegetation structure of the woody plant communities in Boda natural forest. Systematic sampling method was used to collect the vegetation data. Accordingly, 60 plots of 20 x 20 m (400 m 2 ) quadrats were laid at every 50 m along five transect lines from south to north direction using compass. Vegetation parameters such as diameter at breast height (DBH), height and density of the study woody species were recorded, and all the collected vascular plant species were brought to National Herbarium of Ethiopia for identification. Vegetation classification was performed using R program Version 2.15.2 software vegan and labdsv packages. The Sorensens's similarity coefficient and Shannon-Wiener diversity index were also used to detect similarities among communities and to compute species diversity and evenness between the plant communities, respectively. A total of 95 species belonging to 76 genera and 58 families were identified from the forest. The collected species were composed of 34.7% trees, 45.2% shrubs, 13.6% liana, 3% epiphyte, 1% trees/shrubs and 1% tree/liana. Five community types, Galiniera saxifrage-Maesa lanceolata, Juniperus procera-Myrsine Africana, Carissa spinarum-Helichrysum citrispinum, Osyris quadripartite-Rhus ruspolii and Acacia abyssinica-Gomphocarpus fruticosus were recognized from the hierarchical cluster analysis. Generally, the forest was dominated by the small sized trees and shrubs indicating that it is in the stage of secondary regeneration. The presence of strong anthropogenic disturbance in the area necessitates the need for an immediate conservation action in order to ensure the sustainable utilization and management of the forest.

Abbreviation: DBH, diameter at breast height; FAO, food agriculture organization of the united nations; GPS, global positioning system; MASL, meter above sea level IntroductionEthiopia has one of the longest forest plantation histories in Africa. Forest plantations in Ethiopia are mainly monocultures of exotic species, such as Eucalyptus globulus, Eucalyptus camaldulensis, Cupressus lusitanica, Casuarina cunninghamiana, Pinus patula, Pinus radiata, and the native species Juniperus procera. Accordingly, in the end of the 19 th century Eucalyptus species were introduced to satisfy the high demand of firewood.1,2 In addition to this, in the year 2005 it was estimated that Ethiopia had 509000 hectares of plantations, mainly monocultures, of Eucalyptus, Cupressus and Pinus species and 20000 hectares more were expected to be established by the year 2010. Forests provide a habitat for uncounted creatures and microorganisms, and over millions of people also depends on them for timber production, firewood, fruit, resins and other products. Appropriate monoculture plantation of fast-growing species like Eucalyptus species, Acacia, Teak, Poplar, etc., has demonstrated to be one of relevant approach for afforestation programs, both in economic and ecological purposes, particularly, the only effective obtion to initially reforest the degraded areas, then to transform into permanent forest. 4 During recent years, the planting of large areas of fast growing trees species has set off much controversy, especially in the developing world. Critics of these "fast-wood" plantations include environmentalists, who argue that they are substituting natural forests and causing harm to wildlife, water bodies and the soil, and local communities, who complain that plantations are taking over land which previously provided them with the means to feed themselves and earn a living.5 Whereas, plantations have been suggested to promote native plant species understory regeneration, and thus increase biodiversity.6-9 The mechanisms that encourage the understory regeneration involves shading off grasses, enhancing soil nutrients (through uptake by deep roots and litter fall), bettering micro-climate, and in general increasing the chance for seed germination and establishment, which an area of highly degraded sites.8 Furthermore, plantations can also protect sites from further degradation by preventing soil erosion and reducing fire hazard. For these reasons, trees of exotic or native origin are often planted on degraded areas for rehabilitation, in order to preventing further site degradation and catalyzing native plant colonization. Particularly mixed tree plantations are believed to promote the regeneration of a great diversity of species in their understory than pure species of plantation. They could also create a greater variability of habitat conditions that may favor seed dispersal, germination and growth of tree species.10 On the other hand, some believe that the regeneration of indigenous woody species under the canopy of exotic tree planta...

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Clonal propagation enables favourable crop genotypes to be rapidly selected and multiplied. However, the absence of sexual propagation can lead to low genetic diversity and accumulation of deleterious mutations, which may eventually render crops less resilient to pathogens or environmental change. To better understand this trade-off, we characterize the domestication and contemporary genetic diversity of Enset (Ensete ventricosum), an indigenous African relative of bananas (Musa) and a principal starch staple for 20 million Ethiopians. Wild enset reproduction occurs strictly by sexual outcrossing, but for cultivation, it is propagated clonally and associated with diversification and specialization into hundreds of named landraces. We applied tGBS sequencing to generate genome-wide genotypes for 192 accessions from across enset's cultivated distribution, and surveyed 1340 farmers on enset agronomic traits. Overall, reduced heterozygosity in the domesticated lineage was consistent with a domestication bottleneck that retained 37% of wild diversity. However, an excess of putatively deleterious missense mutations at low frequency present as heterozygotes suggested an accumulation of mutational load in clonal domesticated lineages. Our evidence indicates that the major domesticated lineages initially arose through historic sexual recombination associated with a domestication