Biomass and carbon stock potential of Bauhinia thonningii across different land-use types in the drylands

Land-use systems are a key factor influencing the biomass and carbon sequestration potential of a given plant species. This study aimed to estimate the above- and belowground biomass and carbon sequestration potential of the Bauhinia thonningii tree across different land-use types in northern Ethiopia. Vegetation and soil data were collected from 72 sampling plots (100 m × 50 m) in cultivated and grazing land-use types in the Tselemti district, Tigray region, Ethiopia. Soil organic carbon stocks were calculated from measured carbon contents between 0–15 and 15–30 cm soil depths and bulk density values for cultivated and grazing land-use types. B. thonningii dendrometric parameters showed significant variation among the land-use types. The highest aboveground biomass (16.57 ± 3.64 Mg ha^-1), aboveground carbon (8.28 ± 1.82 Mg C ha^-1), total carbon stock (65.58 ± 3.92 Mg C ha^-1), and CO₂ sequestration (237.52 ± 14.37 Mg C ha^-1) were observed in grazing lands compared to cultivated lands. Dendrometric parameters, above- and belowground biomass, and carbon sequestration were significantly higher in grazing lands than in cultivated lands. Soil organic carbon was higher in the upper surface layer (0–15 cm) than in the sub-surface layer (15–30 cm) for both land-use types. Basal area, aboveground biomass, belowground biomass, above- and belowground carbon stocks, total carbon stock, CO₂, and total biomass carbon stocks exhibited a perfect to moderate range of positive correlation with each other, while showing a low positive correlation with land-use types (p < 0.05). Grazing land with B. thonningii trees possesses a higher carbon stock than cultivated land, showing the potential for increasing biomass and carbon stock in grazing land systems by scaling up similar practices. Improved tree-based farming systems can contribute to mitigate global warming, support carbon financing initiatives, and serve as a benchmark for comparing future changes in biomass and carbon stocks.