Environmental determinants of tree productivity and biomass carbon stock in semi-arid Ethiopia

Trees are crucial for climate change mitigation and adaptation. Assessing their ability at the individual tree level is effective because it allows precise quantification of carbon storage, which supports better management and conservation strategies for climate change responses. This study quantifies the carbon stock of Dobera glabra and examines how environmental factors such as land-use changes, soil properties, and tree size affect fruit occurrence in Ethiopia. Using a systematic random sampling design, 25 plots (20 m × 20 m) per land use type were established, where presence, tree growth, fruit and soil properties were measured. Logistic regression examined relationships between fruit occurrence and environmental variables, while Kruskal-Wallis tests compared biomass between fruit-bearing and non-fruit-bearing trees. Results showed fruit frequency was 100% in riverine areas but only 26% in grazing lands (p < 0.05). Soil cation exchange capacity, silt content, and slope showed significant effect on fruiting (p < 0.05). The average carbon stock was 7.135 ± 6.277 ton/ha in riverine land and 1.085 ± 1.098 ton/ha in grazing land. Fruit-bearing trees (4.45 ± 2.83 kg) had significantly higher total biomass than non-fruit-bearing (1.03 ± 0.73 kg) (p < 0.001), indicating greater carbon sequestration potential. These findings highlight the importance of assessing carbon stocks and reproductive status at the individual tree level to effectively link climate change mitigation and adaptation efforts. Conservation and restoration of riverbanks with Dobera glabra can enhance ecosystem services and resilience in arid and semi-arid landscapes.