Woody vegetation dynamics in the rangelands of lower Omo region, southwestern Ethiopia

• Published in: Journal of arid environments Vol. 89; pp. 94 - 102
• Main Authors: Belay, T.A., Totland, Ø., Moe, S.R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.02.2013; Elsevier
• Subjects: altitude; Animal and plant ecology; Animal mobility; Animal, plant and microbial ecology; Arid and semiarid rangeland; Biological and medical sciences; browsing; Bush encroachment; Demecology; Density; Dynamics; Ecology; ecosystems; Fundamental and applied biological sciences. Psychology; humans; Image classification; land cover; land use; Livestock; Non-equilibrium; Plants and fungi; Rainfall variability; Rangelands; rivers; semiarid zones; Synecology; Terrestrial ecosystems; Towns; Vegetation; vegetation cover; Ethiopia; East Africa; Sub-Saharan Africa; Africa; Animal mobility; Bush encroachment; Arid and semiarid rangeland; Rainfall variability; Image classification; Non-equilibrium; Arid environment; Tropical zone; Mobility; Shrub encroachment; Vegetation dynamics; Image; Rain; Semi arid zone; Classification; Rangeland
• ISSN: 0140-1963; 1095-922X
• DOI: 10.1016/j.jaridenv.2012.10.006

Woody encroachment is one of the several factors aggravating rangeland degradation in arid and semiarid areas. The goal of this study is to improve our understanding about the relationship between woody encroachment and its potential drivers by analyzing the temporal and spatial pattern of land-cover changes in the lower Omo region of southern Ethiopia. We used a combination of multi-temporal images, as well as climatic and demographic data for the analysis. Between 1985 and 2010 woody vegetation cover increased by 30.6% in the pastoral landuse type, while declining by 4.4% in the semipastoral areas. The increment was negatively associated with altitude and browser livestock density. However, contrary to the traditional presumption, it was not associated with grazer livestock density. Moreover, woody encroachment was higher in remote sites, farther from rivers and towns, where there is relatively lower human activities and livestock disturbance. The finding suggests the ecological significance of landuse type and livestock browsing to regulate the dynamics of woody vegetation in disturbance-adapted rangelands. Thus, a careful introduction of native larger browsers into woody encroached pastoral areas may help to facilitate rapid ecosystem recovery. ► We quantified land-cover/landuse changes in a semiarid rangeland, since 1985. ► We related the woody cover change within 25 years with various potential drivers. ► It declined in highland semipastoral areas, while increased in lowland pastorals. ► The increment was related to high rainfall variability and lower browser density. ► Introduction of large browsers into encroached sites may facilitate rapid recovery.