WOODY SPECIES DIVERSITY AND CARBON STOCK POTENTIAL OF PARKLAND AND COFFEE-BASED AGROFORESTRY SYSTEMS, HABRO DISTRICT, EASTERN ETHIOPIA

Abstract

Agroforestry practice is well known in eastern Ethiopia and multifunctional working landscape and can play in conserving and enhancing biodiversity and carbon sequestration. Despite some studies related with plant species diversity, its contribution and carbon stock potential of agroforestry. But the study on woody species diversity and carbon stock potential of coffee-based and parkland agroforestry systems in a single document is not well studied. The study was carried out to assess woody species composition, diversity, carbon stock and effect of species diversity on carbon stock of parkland and coffee-based agroforestry system. The study was conducted in Habro district eastern Ethiopia. Sixteen study plot representative of each agroforestry system was selected randomly. Inventory of the woody species assessment were employed in the 40×40 and 20m*20-meter plot for parkland and coffee-based agroforestry systems and 5m*5m was laid down for coffee shrub and 1*1 meter for soil sample. For woody species with ≥ 2.5cm DBH, and tree height were taken. soil samples were taken from the four corners and center in two soil depth (0-20 cm and 20-40 cm). Basal area, stem density diameter and height class distribution were computed to characterize structure of woody communities. Species diversity, biomass and soil carbon stock were also determined. Biomass carbon was estimated using allometric equations. A total of 57 woody species belonging to 31 families were recorded. Of all species identified, 38 woody species were recorded in parkland and 43 woody species were recorded in coffee-based agroforestry system. The study indicated that the woody species Shannon and richness were higher at coffee-based than parkland agroforestry. The biomass carbon of coffee-based agroforestry was considerably higher (33.94Mg C ha-1) than the parkland agroforestry (10.28Mg C ha-1). Total C stock (biomass C + soil Carbon) range from 124.72 to 192.64 Mg C ha-1 with average value (158.68 Mg C ha-1), indicating that a major portion of the total amount of C in the system is stored in the soil. However, relationship between woody species diversity and carbon stock of both agroforestry system have almost positive relation but not significant except Shannon diversity significantly positive relation with total carbon stock in parkland agroforestry. Finally, the results provide an input for implication of the future potential of agroforestry management in biodiversity conservation and climate change adaptation and mitigation purpose of national program.