Assessment of the impact of woody species encroachment on plant species diversity and the livelihood of pastoralists in southeastern Ethiopia

Abstract

The study aimed to assess the encroachment of woody plants on the rangelands of the Dallo Manna district of Bale Zone, and their impact on plant species diversity and pastoral livelihoods. Plant data were collected from 45 plots at encroaching sites and 4 plots at non-encroached sites, with a size of 20 m × 20 m for comparison. Data on pastoral perceptions were collected through questionnaires, interviews with key informants, and focus group discussions. A total of 62 woody species were recorded at both non-encroached and encroached sites, of which 58 species (93.5%) were recorded at non-encroached sites and 24 (38.7%) at encroached sites. Dichrostachys cinerea (L.) Wight and Arn. was the most abundant and dominant invasive woody species, followed by Senegalia mellifera (Vahl) Siegler and Ebinger, and Dalbergia microphylla Chiov. Overall, our results indicated that the effects of woody species encroachment significantly affected rangeland vegetation conditions and livelihoods. The major drivers for the encroachment were found to be fire suppression, overgrazing, and dispersal syndromes. However, in order to understand the exact causes of the woody plant encroachment, multiple variables should be considered in future research. For the successful control of encroachment, insights from an integrated approach will benefit from both local traditional and scientific knowledge of the ecology.