Abstract:
Rapidly increasing population, deforestation, over cultivation, expansion of cultivation at the expense of lands under communal use rights (grazing and woody biomass resources), and several other factors have led to ecosystem degradation in the Central Rift Valley region. Conscious of this fact government and other stakeholders have initiated and led number of interventions including Ecosystem Rehabilitation programmes. However, not many studies have been conducted towards enhancing the understanding of the impacts of these ecosystem rehabilitation projects on the cover and structure of vegetation and soil chemical properties. The current study was undertaken in Kelala Dalacha Conservation and research site in Ada’a District, East Shoa Zone, Oromia where an ecosystem rehabilitation project has been undertaken. Apart from studying the impacts of ecosystem rehabilitation on the cover and structure of vegetation, its impact on soil chemical properties was also studied. Determining plant community types and floristic composition were also the focus of this study. Random sampling method was used to collect vegetation data. All wood species encountered in the quadrants established randomly were recorded. Four satellite images of the study area, distributed between 1988 and 2018 were analyzed using Arc GIS software to assess the Land Use Land Cover (LULC) changes of the area. Composite sampling was used in soil sample collection and soil was analyzed for selected chemical properties. Data was analyzed using both descriptive and inferential statistics. Cluster analysis was used for vegetation classification into different community types using the statistical software R-package for windows version 3.3.2. The plant community types were named after two dominant species were selected. Species diversity and evenness was calculated using Shannon-Wiener diversity index. Soil chemical properties were analyzed in the National Soil Test Laboratory following standard procedures. The data from soil laboratory were subjected to one-way analysis of variance (ANOVA). A total of 53 vascular plants belonging to 46 genera and 25 families were recorded from the area. The general pattern of distributions of woody species in the area across the DBH classes displayed inverted J-shaped pattern of distribution. The lower DBH classes were found to have relatively higher number of individuals than that of the middle and the top classes; indicating the use of enclosure for rehabilitation of the vegetation. Vegetation cover was 58.1%, 64.47%, 80.32% and 88.43% in 1988, 1998, 2008 and 2018, respectively, showing the positive contribution of area enclosure in ecosystem rehabilitation. The bare land in 1988 was changed to either woody species or Grasses nowadays. A strong correlation coefficient of soil parameters was seen among the soil samples collected in the area. It was concluded that area enclosure had positive impact in vegetation cover and soil chemical properties. Therefore, using area enclosure for restoration of ecosystem function and biodiversity conservation was recommended as a result of this study.