Preliminary estimate of carbon sequestration potential of Faidherbia albida (Delile) A.Chev in an agroforestry parkland in the Central Rift Valley of Ethiopia

Agroforestry parklands are a common land-use in Ethiopia and many parts of the tropics. These systems play an important role in climate change mitigation and adaptation, through carbon (C) sequestration. However, C sequestration in both tree biomass and soil has not been extensively studied for parklands of the Central Rift Valley (CRV), Ethiopia. Therefore, here we sampled a small number of F. albida trees and soil from the Adulala watershed, CRV, to provide a preliminary estimate of the C sequestration potential of these systems. Mean above-ground total dry biomass of trees was estimated at 844 kg tree^-1. Tree density was 5.80 ha^-1, which corresponded to 2.45 t C ha^-1 in above-ground biomass and 0.76 t C ha^-1 below-ground; and 118 t C ha^-1 in soil (0–80 cm depth) under trees, compared to 84 t C ha^-1 in the soil of crop-only areas. We speculate that if tree density was increased to 100 trees ha^-1, the rate of soil C sequestration could be estimated as 0.48 t C ha^-1 year^-1 for 42 years. Faidherbia albida tree density is sparse in the study area, but could be increased by encouraging farmers to protect planted seedlings or natural regeneration.