The role of enclosures in the recovery of woody vegetation in degraded hillsides of biyo and tiya, central and northern Ethiopia

Much of the earth degraded, is being degraded or is at risk of degradation. In most of the tropical dry Afromontane forests, deforestation has extended to the form of devegetation of land cover resulting in losses of biodiversity and erosion of soil particles and its organic content. In Ethiopia, Bush and shrub lands, which account for 66% of the countries forest resources, are the ecosystems affected by this phenomenon. Once these lands have been converted in to degraded lands, it is not clear if they will recover in to forest when they are permanently enclosed. this study focuses on the regeneration of dry land forests after enclosure following vegetation destruction. We discussed the fate of dry degraded lands through enclosure practices following human disturbance. Enclosure at Biyo-Kelala and tiya and the corresponding adjacent open areas are used for the study. The study focuses on the assessment of the woody vegetation recovery and the soil seed bank status of dry degraded lands following enclosures including the socio economic setting, which generally will give an overview of the restoration ecology of degraded lands. According to the results of this study, enclosures in both sites have greater woody species diversity than open grazing lands. Dodonaea, Acacia saligna, Grewia, Acacia abyssinica, Acacia seyal. Acacia etbaica and Acacia tortilis are very well represented in biyo enclosure while Echinops, Sida and Dodonaea are well represented in the open area. The density of woody species was greater in the enclosure of Tiya than the open area. But, Acacia etbaica, Euclea and Rhus natalensis are equally important in both sites. Density was even greater in the open area of Biyo-Kelala than the enclosure. but, the majority of the vegetation in the open area (62%) was contributed by one species, Echinops. The population structure show high density at lower DBH classes and lower density at higher ones for most species in the enclosures and for a few species in the open areas. The richness of woody species was substantially higher in enclosures than open areas, indicating the importance of enclosures for the conservation of biological diversity. The woody portion of the soil seed bank is minimal (except the planted Acacia saligna in Biyo enclosure) in most of the study plots. It is asserted that most of the seeds of woody species in the soil might have escaped through germination, thereby contributing to the standing vegetation. The horizontal and vertical distributions of the soil seed bank also show significant differences between the two land uses in both study sites. There is also a difference in seed density per meter square F (1, 68) = 14.8, P = 0.0002 for Biyo-Kelala and F (1, 43) = 4.3, P = 0.04 for Tiya) for the two study sites.The high density of Acacia saligna seeds in the soil seed bank and rarity of some important indigenous species like Olea and Stereospermum in the standing vegetation indicated the importance of planting both exotic and indigenous species for improving the soil seed bank and avoiding local extinction of species respectively.The result of the questionnaire survey also indicate that 93.7% of the respondents have positive attitude towards the practice, the remaining 6.3% are the younger community groups without farmland and also with no benefits from the enclosure. However, a small group (village level) community management system with an efficient benefit sharing mechanism seems to be more practical than parceling enclosures for individuals.From the results of the study, the emergence of enclosure as an alternative strategy is a relatively cheap as well as, convenient management option to mitigate of counteract degradation of the environment in general and natural resources in particular, while at the same time providing economic benefits for the local community. Nevertheless, it is not possible to design national model for the management of enclosures, it is the local people and associated stakeholders that should design local management rules for enclosures.In the end, the practice of enclosures on degraded lands is suggested to be one alternative strategy for domestic wood production and the conservation of the natural resources of a site.