make an assessment of plant diversity, plant community types, structural analysis of woody plant species and quantify the amount of carbon stock and its relation with environmental gradients. A systematic sampling technique was used and a total of 102 and 30 sample plots each with 20 x 20 m were laid along the altitudinal gradient for Gergeda and Anbessa forests, respectively. From Gergeda forest a total of 178 plant species that belong to 150 genera in 71 families were identified, out of which 45.5%, 12.92%, 11.23% and 30.33% were trees, shrubs, climbers and herbs, respectively. Fabaceae was the most abundant family followed by Asteraceae, Acanthaceae, Celastraceae and Poaceae. From Anbessa forest a total of 118 plant species were identified which belong to 93 genera in 46 families. Out of these, the percentage of trees, shrubs, climbers and herbs were 33.05%, 11.86%, 11.86% and 43.22%, respectively. Fabaceae was the most abundant family followed by Asteraceae, Poaceae and Lamiaceae. The present study reported 13 and nine endemic plant species are present in Gergeda and Anbessa forests, respectively. Moreover, 44 and 29 plant species were recorded as new records for Wellega floristic region from Gergeda and Anbessa forests, respectively. The structures of woody plant species in the two forests were also computed and six general population structure patterns were recorded from each forest. Four plant communities from each Gergeda and Anbessa forests were identified. In Gergeda, Pouteria adolfi-friedericii – Syzygium guineense community was both the most diverse (Hʹ=4.43) and species rich community with 87 species; whereas Arundinaria alpina dominated community was the least diverse (Hʹ=0.15) and the least species rich community with five species. In Anbessa forest Combretum collinum - Dombeya quinqueseta -Securidaca longepedunculata community was the most diverse community while it has 12 species. Whereas, Oxytenanthera abyssinica - Combretum molle - Syzygium guineense subsp. macrocarpum community was the lease diverse with Hʹ 0.16, while it was the most species rich community with 30 species. The mean total carbon stock density of Gergeda forest was found to be 717 tons Carbon ha-1, out of which 466, 93, 2.5 and 155 tons Carbon ha-1 were stored in the above ground, below ground, litter and as soil organic carbon, respectively. The mean total carbon stock density of Anbessa forest was also found to be 353 tons ha-1 Carbon, out of which 169, 34, 1.15 and 149 tons of Carbon were stored in the above ground, below ground, litter and as soil organic carbon, respectively. The one way analysis of variance showed that, there is a significant diiference between different carbon pools at both forests. Environmental gradients also showed a significant influence on the amount of carbon stored in the different pools. Altitude and aspect strongly influences the amount of carbon stored in plants. Visualization model of Altitude verses carbon stock showed a bell shaped structure, which implies that carbon stock increases as altitude increases and then reaches to its peak around 2250 m.a.s.l. and turns down while altitude increases beyond this. The two forests can play a significant role in biodiversity conservation as well as climate change mitigation, since they can sink 35,612,861 and 5,329,610 tons of Carbon, respectively. Key words/phrases: Plant diversity, floristic composition, forest structure, carbon sequestration and environmental gradients.