Biomass and soil carbon stocks under different coffee agroforestry systems in Hurumu District, southwest Ethiopia

Understanding the carbon storage capacity of coffee agroforestry systems is essential for promoting sustainable land use and addressing climate change. However, there is a lack of scientific data on biomass and soil carbon stocks in Ethiopia's coffee-growing regions. This study estimated biomass and soil carbon stocks in garden, semi-forest, and forest coffee production systems in Hurumu District, southwestern Ethiopia. Data were collected from 24 plots measuring 20 m × 20 m, with soil samples (0–30 cm) analyzed for organic carbon and biomass carbon estimated using allometric equations. One-way ANOVA was used to compare the mean carbon stocks among the systems. The results showed that the forest coffee system had the highest mean total carbon stock (635.12 ton/ha), followed by the semi-forest (450.87 ton/ha), and the garden system (294.39 ton/ha). These variations were statistically significant at the 5% level (p < 0.05). The study identified the key shade tree species that contribute to carbon storage in each system: Podocarpus falcatus in the forest (45.73 ton/ha), Cordia africana in the semi-forest (35.74 ton/ha), and Prunus africana in the garden system (29.98 ton/ha). The results suggest that promoting these species enhances carbon storage and supports climate resilience.