Biomass and Soil Carbon Stocks Assessment of Agroforestry Systems and Adjacent Cultivated Land, in Cheha Wereda, Gurage Zone, Ethiopia

Abstract

Abstract The present study examined biomass and soil carbon stock potentials of different AFS (homegarden and woodlot) and cultivated land in Cheha Wereda, Gurage zone, Ethiopia. The sites were selected based on dominance and accessibility through reconnaissance survey prior to sampling. A total of 60 sample plots (20 plots from each land use type) of 20 m x 20 m were randomly selected. Above ground biomass and below ground biomass were calculated by adopting available site and species allometric equations. A total of 120 Soil samples (0–20 and 20-40 cm) were also collected from selected cultivated lands using to determine soil organiccarbon (SOC), pH, texture and bulk density. Additional 120 soil samples were collected to determine soil bulk density. The results showed that the total ecosystem carbon stocks in homegarden and woodlot AFSwere estimated at 100.4 and 72.9 Mg C ha-1 respectively. The SOC stock was significantly different among the studied land uses.The highest SOC stock was recorded in homegarden agroforestry system (94.2 Mg C ha-1) followed by cultivated land (73 Mg C ha-1) and woodlot agroforestry (68 Mg C ha-1). The total ecosystem carbon stock ranged between 55 -140 MgC ha-1. Homegarden holds the highest contribution for both biomass and SOC for total ecosystem carbon accounting 84.3% for total SOC and the remaining for total biomass. Homegarden AFS has the highest SOC stock. Conversion of homegarden Agroforests to cultivated land would decrease SOC stock by 23% and wood lots to cultivated land would increase SOC by 7%. The study also revealed that AFS enhance carbon stocks accumulation both in the biomass and soil besides the socioeconomic benefits over cultivated land. Hence, AFS can be taken as potential climate change mitigation strategy in central highlands of Ethiopia.