VEGETATION COMPOSITION OF RANGE LAND AND ITS EFFECT ON LIVESTOCK AND SOCIO-ECONOMICS STATUS OF THE PASTORALISTS IN EWA DISTRICT, AFAR REGIONAL STATE, ETHIOPIA

Abstract

This study was conducted on the range land of Ewa district, Afar regional state, Ethiopia with the objective to analyse the current vegetation composition of the range land and its effect on the livestock and socioeconomics of the pastoralists of the study area. Stratified sampling design was used for this study to collect vegetation data. The comprehensive vegetation data were collected from 72 sample plots laid on the four transects. The size of the main plot was 20mx20m for tree species, with in this plot five sub-plots of 5 m x 5 m were set-up within each 400m2 of the main plot, to collect data on shrubs. Within each 5mx5m sub-plots another 1m x 1m sub-plots were set-up to collect data on the herbs and grass species along the line transects approximately at 400m intervals along north-south directions. Socio-economic data were analyzed using descriptive statistics by SPSS version 20 software packages. A total of 75 species of vascular plants belonging to 60 genera and 26 Families were identified from 72 plots examined from the study area. Out of these plant species, 15 (20%) were trees, 23 (30.67%) were shrubs, 25 (33.33%) were herbs, and 12 (16%) were grasses. Fabaceae and Poaceae were found to the dominant families in the study area. The Shannon diversity index of the woody and herbaceous species was 2.10, and evenness index was 0.50 in the study area. Three plant communities were identified from hierarchical cluster analysis using R 3.3. Software packages i.e. community I was Parthenium hysterophorus-Tribulis terrestris, community II was Acacia oerfota-Salvadora persica and community III was Enteropogon species- Andropogon canaliculatus which were the dominant communities in the site. The density of woody species had DBH > 2.5cm and were 149 per ha for tree and 173 per ha for shrub species. The total basal area calculated was about 3.25 m2/ha for tree plants species > 2.5 cm in DBH and shrub plant species were 0.12 m2/ha. The tree species like, Acacia tortilis, A. nilotica and Dobera glabra had high IVI value, and the shrub species like, Grewia feruginea and Acacia oerfota had high IVI value. The study indicated that the population structure of the most tree species was identified to have poor regeneration status while shrub species were found to have good regeneration status which means expansion of low desirable (unpalatable) shrub species, which could be an indicator on the beginning of bush encroachment in the study area. The most dominant and frequently herbaceous species occurred in the rangeland were Parthenium hysterophorus, Andropogon canaliculatus, Pennisetum polystachion, Enteropogon species and higher density of the herbaceous species were Andropogon canaliculatus, Pennisetum polystachion, Enteropogon species grass and Parthenium hysterophorus, Tribulis terrestris and Celosia trigyna in the study area. Based on the Ecological Index Method (EIM), most of the transect study areas were characterized poor condition of the rangeland. Most of the pastoralists in of the study district believed that the rangeland vegetation composition was dramatically changed from grassland to bushland within the past two decades, Due to this major reason the pastoralist tended to change their livestock herd structure into small ruminant (goats and sheep) that required affordable feed resource and browser animal (camel). Due to the change of livestock population (herd structure) which had been affected by the vegetation trend, the pastoralist livelihood has been changed that means economically very poor and socially disturbed.