WOODY SPECIES DIVERSITY, VEGETATION STRUCTURE AND CARBON STOCK POTENTIALS OF HALLIDEGHIE WILDLIFE RESERVE, ETHIOPIA

Abstract

The study was carried out in Hallideghie Wildlife Reserve, Afar National Regional State, Ethiopia with objectives to assess woody species diversity, vegetation structure and carbon stock potential of the reserve. Woody plant species diversity, vegetation structure and carbon stock potential of the study area undertaken in four vegetation type by using stratified sampling approach. A total of 12 horizontal transect lines were laid out in the four vegetation types and a total of 36 quadrates of 20mx20m size were established for collecting the woody species data. For collecting soil data 180 sub quadrates were set-up in the 36 main quadrates and soil sample was taken from a depth of 0-10, 10-20 and 20-30cm to make one composite sample for each soil depth to be considered for analysis. Bulk density, texture and organic carbon were analyzed in Haramaya University soil chemistry laboratory. The vegetation and soil data were analyzed statically in one-way ANOVA using R statistical software. A total of 40 woody species of 11 families and 23 genera were recorded in the study area. Among which, 17 (42.5%) ,12(30% and 11 (27.5%) were tree, shrub and tree or shrub respectively. The most dominant species was Acacia senegal (80.56 ind. ha-1) and the least dominant species were A. oliveri (5.56 ind. ha-1), Dichrostachys cinerea (5.56 ind. ha-1) and Ricinus communis (5.56 ind. ha-1) were collected. The most ecologically important species with highest IVI were A. senegal (IVI=22.47%), Cordia monoica (IVI=15.21%) and A. tortilis (IVI=15.15%). The species which needs conservation measures with least IVI were Dichrostachys cinerea (IVI=1.15%), Ricinus communis (IVI=1.22%) and A. albida (IVI=1.82%). The average Shannon-wiener diversity index and evenness was recorded as (H’=1.7) and (J=0.97) respectively in the study area. The Shannon-wiener diversity index was significantly varied among vegetation as 1.7±0.22 with F=8.37, p=0. 003. The highest AGC was recorded in bushland (28.31±1.18 t. ha-1) to be followed by wooded grassland (24.44±2.23 t. ha-1), open grassland (20.68±2.65 t. ha-1) and shrubland (10.81±1.6 t. ha-1) in the study area. There was significant variation of AGC among vegetation type. The highest BGC was recorded in bushland (5.66±0.24 t. ha-1) and the lowest was recorded in shrubland (2.16±0.32 t. ha-1) were recorded. The highest soil organic carbon was recorded in bushland (79.14±7.89 t. ha-1) to be followed by wooded grassland (54.96±3.57 t. ha-1), shrubland XIV (51.51±3.01) and open grassland (42.95±2.96). The soil organic carbon was significantly varied among vegetation type p<0.05. The overall total carbon stock sequestrated in Hallidighie Wildlife Reserve was 333.01ton ha- 1and correspondingly 1214.81-ton ha-1 equivalent carbon dioxide was mitigated in the area. The variation of species diversity and carbon stock might come from anthropogenic disturbances and the local community livestock intervention in the study area. Therefore, the concerned bodies should take action towards management of the reserve for sustainability and ecosystem balance of the study area.