WOODY SPECIES DIVERSITY, COMPOSITION AND CARBON STOCK OF OBI FOREST IN DEDER DISTRICT OF EAST HARARGHE, E

Abstract

The study was conducted in Deder District of Obi forest, with the objectives of assessing the woody species diversity, composition and estimating of the carbon stock of the forest. A systematic sampling method was used to conduct the vegetation sampling. In order to collect vegetation data, a total of 36 quadrats, each with the size of 20 m x 20 m for tree, 5 m x 5 m for shrubs at an interval of 100 m, were laid along altitudinal variation. Aboveground biomass was estimated by using allometric models while belowground biomass was determined based on the ratio of belowground biomass to aboveground biomass factors. For litter and soil sample collection, five sub-quadrats each with the size of 1 m x 1 m were established at four corners and center of every quadrat. Plant Species Diversity analysis was carried out by using Shannon Weiner index. SPSS software version 20 was used to analyze the data. The study of woody plant species in Obi forest shows a total of 22 species from 16 families and 20 genera were identified in this study. Juniperus procera was the dominant species counting 243 trees, and Cupressus lucitanica and Olea africana were the second and third dominant species recorded with 207 and 99 trees respectively. The value of Shannon –Wiener Diversity Index (H’) of the whole vegetation of this study area was 2.29 with the evenness or equitability value (J= 0.74). From the analysis of dif erent carbon pool, the total mean carbon stock of the forest was 232.935 t ha  1 whereas aboveground carbon stock share 60.82 t ha  1 , belowground carbon stock 15.814 t ha  1 , litter carbon stock was 2.49 t ha  1 and soil organic carbon (SOC) 153.8 t ha  1 . Carbon stocks variation along altitude showed that all carbon pools were not significant at (p<0.05) along altitudinal gradient. Analysis of correlation of carbon stock with species diversity was done using linear regression. Accordingly, aboveground biomass carbon stock and species diversity had weak positive correlation (R = 0.049). Similarly, the below ground, litter and soil carbon stock had also weak correlation with species diversity (R = 0.049 R =0.006, R = 0.052 respectively). So as to improve the ecological function of the forest, the community, government of ices and non-governmental organization should jointly work in forest conservation and management. People around the forest is still cutting tree for fire wood and putting the forest in danger, the introduction of alternative energy sources is recommended to the area to reduce impact on the forest as well as to increases the diversity of the forest and its carbon stock potential