Biomass and Carbon Sequestration Potential of Oxytenanthera abyssinica in the Homestead Agroforestry System of Tigray, Ethiopia

Abstract

Oxytenanthera abyssinica forms an important constituent in the homestead agroforestry system of Tselemti district of Northern Ethiopia. Biomass and carbon sequestration potential of O. abyssinica in the land managed by farmers was studied from November to January 2013/14 in Serako kebele. Samples of six culms per age classes in three replications, 18 culms in total were harvested for biomass analysis. Allometric equations were then developed relating to leaf, branch and culm biomass with breast height diameter (DBH) and Age as independent variables. To evaluate the effect of Age and DBH on total biomass of O. abyssinica, 9 different treatments with three replications were used. In total, 27 culms were randomly selected for biomass and carbon stock determination based on the developed allometric equation. Samples were then collected from three levels of age, i.e. less than one year, one to three years and greater than three years at three DBH levels of 2.55 – 3.18 cm, 3.19 – 3.82 cm and 3.83 – 4.46 cm. Carbon fraction of O. abyssinica was determined using destructive ashing method by taking sample specimens both from the above ground and below ground biomass. Carbon stock was significantly higher in one to three and greater than three years than less than one year culm age (P<0.001). Older culms were capable to sequester more carbon than younger culms with 3.8, 3.9 and 3.5 kg culm^-1for the three age classes respectively. O. abyssinica has a significant effect on climate change mitigation through carbon sequestration.

Key - words: allometric equation, carbon sequestration, Oxytenanthera abyssinica