Tree diversity and biomass carbon stock analysis along altitudinal gradients in coffee-based agroforestry system of Western Ethiopia

Abstract

Agroforestry systems are thought to reconcile biodiversity protection with food production and as a means of climate change adaptation and mitigation options. The contribution of a coffee-based agroforestry system to tree diversity and carbon stock along altitudinal gradients in Western Ethiopia was assessed. At 500-m intervals, six transect lines were methodically set up throughout the altitudinal gradient. There were made a total of 60 sample plots, each measuring 40 m by 40 m. A total of 34 woody species were identified. Biomass carbon stocks and tree diversity were quantified across altitudinal gradients. In the middle altitude, there were more woody species (28) than in the top altitude, where there were only a few species (16). The tree plants stored around 40.6 t ha⁻¹ of biomass carbon on average. Aboveground biomass had a carbon stock of 32.22 C t ha⁻¹, whereas belowground biomass had a carbon stock of 8.38 C t ha⁻¹. The lower altitude biomass carbon stocks were substantially bigger than the upper altitude, which were 48.4 C t ha⁻¹ and 25.67 C t ha⁻¹, respectively. With increasing altitude, the study found a statistically significant negative link between tree diversity and biomass carbon storage (P < 0.05). The negative link between biomass carbon stock and altitude was that tree parameters that determine the amount of biomass carbon sequestered in a plant, such as basal area, tree diversity, and density, decreased as altitude increased. Despite differences along altitudinal gradients, the systems supported a diverse range of tree species and biomass carbon stocks.

Keywords:

• Agroforestry
• carbon
• coffee
• tree diversity
• altitudinal gradient

Acknowledgements

The authors are thankful to the Center for Environment and Development of Addis Ababa University for providing research funds for Ph.D. students under MoE-Ethiopia. We also thank the CLIFF-GRADS to support “Improving productivity and adaptive capacity of Coffee-based agroforestry systems for enhancing food security in a changing climate in Ethiopia”. Our sincere thanks also go to all workers of Agriculture and Natural Resources, EFCCA, OFWE, and Coffee and Tea offices of Gimbi Zonal and District for their participation in data collection during surveying and interview processes.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Declarations

Beshea Abdissa Chemeda: Conceived and designed the research survey; Performed the data collection; Analyzed and interpreted the data; Contributed materials, analysis tools, or data; Wrote the paper.

Feyera Senbeta Wakjira: Conceived and designed the research survey, Supervised, edited the paper.

Emiru Birhane Hizikias: Supervised, edited the paper.

Additional information

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Additional information

Funding

This work was supported by Addis Ababa University (College of Development Studies, Center for Environment and Development) and the CLIFF-GRADS.