Area ex-closure has recently become a promising option to reverse ever increasing land degradation in Ethiopia. However, comprehensive empirical evidences about the role of ex-closure are just building up. The study was conducted in 10 and 24 year old ex-closures paired with adjacent open grazing land in Haise kebele, Lemo district, southern Ethiopia. The main aim was to assess biodiversity, soil quality and biomass and carbon stock changes due to the impact of the ex-closures. Systematic transect sampling technique was applied to collect data. A quadrat plot size of 20m ×20m and 1m×1m sub-quadrant (nested in the 20m× 20m) was used along transect line for vegetation data collection and harvesting herb and grasses biomass, respectively. Soil at a depth of 20cm and 30cm from five sampling point inside the 20m ×20m at each corner and center were sampled and composite soil were taken and analyzed following standard procedures. Species composition, diversity and density were computed using standard procedures and indices DBH and height were used to describe the structural pattern of the species. Published allometric equations and the loss on ignition method were used to estimate tree and herb carbon stock, respectively. Accordingly, the result showed that vegetation compositions significantly varied with land use types. Sorensen’s similarity coefficient indicated considerable species dissimilarity in the land use types varying between 0.41-0.73. Higher total stand densities of all woody species were observed in ex-closures than open grazing lands. Significantly higher species diversity, richness and evenness were also observed in ex-closures. The overall structure of plant species in ex-closures exhibited an inverted “J” shape pattern of DBH and height class distribution, showing a stable and good regeneration status unlike open grazing lands. Bulk density increased under open grazing land while soil moisture increased significantly in ex-closures. The result also revealed that soil organic matter, total nitrogen, K+, Ca+2 and CEC significantly (p<0.05) increased in ex-closures and positively correlated with duration whereas available phosphorous, Na+ and Mg+2 did no significantly varied. Higher vegetation biomass and carbon stock were observed in ex-closures than in the open areas. A positive significant correlation was observed with ex-closure duration. Species diversity, soil quality and carbon storage were relatively improved due to the practice.