Wolde Mekuria

Carbon Changes Following the Establishment of Exclosure on Communal Grazing Lands in the Semi-Arid Lowlands of Tigray, Ethiopia

Most dryland ecosystems are degraded and are currently far from saturated with carbon. This indicates their potential to sequester a significant amount of carbon through sequestration measures. In this study, we: (1) investigated changes in ecosystem carbon stocks following establishment of exclosure on communal grazing lands, and (2) identified easily measurable biophysical and management-related variables which can be used to predict ecosystem carbon stocks restoration in the semi-arid lowlands of northern Ethiopia. We measured above-ground and soil carbon stocks, determined soil characteristics and collected climatic data and management information from replicated (n = 3) exclosures of 5, 10 and 15 years old which were paired with grazing lands. All exclosures displayed higher ecosystem carbon stocks than the adjacent grazing lands. Differences in ecosystem carbon stocks between exclosures and grazing lands varied between 18 (±2.8) and 40 (±6.3) Mg C ha−1 and increased with exclosure age. In exclosures and in communal grazing lands, much of the variability in ecosystem carbon stocks was explained by a combination of precipitation, silt and clay content, woody biomass, vegetation canopy cover and exclosure age. Our results help to establish baseline information for carbon sequestration projects such as the establishment of exclosures on communal grazing lands, and to predict the expected ecosystem carbon storage under exclosures.

Assessment of bacterial wilt (Xanthomonas campestris pv. musacearum) of enset in Southern Ethiopia

Enset (Ensete ventricosum) production and productivity is threatened by many biotic and abiotic factors among which bacterial wilt of enset (BWE), caused by Xanthomonas campestris pv. musacearum is one of the major factors. There were no reports on the intensity and distribution of bacterial wilt of enset in South Nation Nationalities and Peoples’ Regional State (SNNPRS). Hence, the objective of this study was to determine the distribution and incidence of bacterial wilt of enset in relation to age, altitude and clonal variation in major enset growing districts of South Nation Nationalities and Peoples’ Regional State (SNNPRS). Three major enset growing Zones namely Gurage, Hadiya and Sidama were included in the survey. In each Zone, three Districts were selected based on enset production status and altitudinal variation. The disease was detected in all agro ecologies and districts, but in varying extent. Bacterial wilt prevalence and incidence was highest in Hadiya and estimated at 42.22 and 5.56%, respectively, while both disease prevalence and incidence were the lowest (26.67 and 2.86%, respectively) in Sidama. At District level wilt prevalence varied from 6.67% at Aletachiko District to 76.67% at Lemo District. Bacterial wilt incidence also ranged from 0.74% at Aletachiko District to 10.31% at Lemo District. Wilt prevalence and incidence were at the highest (50% and 5.81%, respectively) in the altitude range of 2000-2500 masl. The disease varied according to the crop growth stage, with severe (4.75%) in Cycle 4 (an age greater than 4) and less severe (0.2%) at Cycle 1 (age of less than one year). Highest disease incidence and prevalence (30 and 6.65%) were noted with a plant age of 4-5 years. The disease was highly associated with administrative Zone, District, altitude, number of clones and spacing in a logistic regression model.