Abstract
Bush encroachment is reducing rangeland productivity in Borana rangelands. This study was conducted in Teltele Woreda of Borana zone, to evaluate the effects of bush encroachment on plant species composition, diversity and its contribution to carbon stock. Bush encroached, non-encroached and bush thinned rangeland types were selected for the study. Nested plots for collecting tree, shrub, herbaceous and soil data were placed systematically along the geographic gradient within each of the rangeland types. Herbaceous plants were clipped to the ground, collected, oven dried, and their carbon stock was estimated. The tree/shrub biomass was estimated using allometric models, and converted to per hectare. A total of 53 vascular plant species belonging to 19 families were identified. Poaceae and Fabaceae families dominated the site. Bush encroachment had reduced diversity and species richness of herbaceous plants, but did not affect other tree/shrub plant diversity and richness. Although bush thinning improved herbaceous diversity and richness, it reduced tree/shrub richness. The tree/shrub aboveground carbon stock in bush encroached areas is greater than non-encroached rangeland types. Soil carbon stock is highest in bush thinned locales. Total organic carbon stock is ranked from largest to least as follows: Bush encroached, >Bush thinned, and >non-encroached. Generally, bush encroachment increased the rangeland carbon stock, but reduced herbaceous plant biomass and density. Key words: Biomass, bush thinned, encroachment, herbaceous, rangeland type, soil carbon stock, climate change.
Highlights
IntroductionEncroachment of woody plants into grasslands, and the conversion of savannas and open woodlands into shrublands, has been widely reported during the past decade (Auken 2000, 2009; Maestre et al, 2009; Eldridge et al, 2011), and this phenomenon has been observed across much of the world’s arid and semi-arid biomes (Andela et al, 2013)
Of the total species encountered in the study area, 12 species (Brachiaria eruciformis, Chlorosis roxburhiana, Cyprus obtusiflorus, Dactyloctenium aegyptium, Doberaglabra, Echinochloa colony, Indigofera arrecta, Endostemon Keller, Justicia calyculata, S. mellifera, Sporobolus pyramidalis and Volkensinia prostrata) were found on all three rangeland types
The results revealed that tree/shrub aboveground and roots biomass and carbon stock was highly affected by the rangeland types
Summary
Encroachment of woody plants into grasslands, and the conversion of savannas and open woodlands into shrublands, has been widely reported during the past decade (Auken 2000, 2009; Maestre et al, 2009; Eldridge et al, 2011), and this phenomenon has been observed across much of the world’s arid and semi-arid biomes (Andela et al, 2013). It is visible in African savannas and grasslands (Mitchard and Flintrop, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International Journal of Biodiversity and Conservation
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
