Environmental sustainability of short-rotation Eucalyptus poles in Uganda

Abstract

Growing short-rotation forests with fast-growing tree species is rising in Uganda to match the ever-increasing demand for wood and wood products. This increasing demand in turn has birthed various short-rotation wood products on the markets like Eucalyptus scaffoldings. Despite this increasing trend of short rotation wood products on the market, the environmental effects associated with these products have neither been studied nor profiled. Using life cycle analysis, the study assessed the environmental sustainability of different product categories of short rotation Eucalyptus poles in Uganda. The study compared the amount of different product categories produced from Eucalyptus plantations, the carbon sequestered by them and the corresponding carbon dioxide emissions generated along the different stages of value chains of Eucalyptus poles. Data were collected over two months using cross-sectional survey of trucks transporting Eucalyptus poles to Kampala City along the two major supply routes. A total of 737 trucks were systematically sampled from four study sessions. The net calorific value of Eucalyptus poles was determined using a bomb calorimeter. Data was analyzed descriptively for product categories, also adopting the carbon equation, transport emission equation, combustion equation, ANOVA tests and a regression analysis between distance travelled and net carbon dioxide emissions for all product categories. From the results, small-sized poles were the most harvested Eucalyptus wood product entering the KMA wood markets. Of the 14,108 m3 inventoried, 68% were small-size poles (=13-15cm diameter) category. Construction poles had the highest volume of 4,142 m3 of the small-size products. Furthermore, small-size categories sequestered the highest amount of carbon (23,881 tCO2e) and lowest for medium-size products (622 tCO2e). Besides, transport emissions were the highest (255 tCO2e) for small-sized poles and lowest (6 tCO2e) for medium sized poles. The end-use emissions were 67,456 tCO2e for the small-size category while medium- and large-size categories had none. Small-size products had positive net emissions (43,830 tCO2e) and yet net negative (-10,293 tCO2e) for large product categories. In conclusion, it was evident that small sized product category contributed the highest inflows of wood volume entering into the market, indicating how much poles for construction are highly demanded. There is a need for bulk hauling means of the short-rotation Eucalyptus poles into the markets to reduce the transportation emissions and development of green end-use options for the short-rotation Eucalyptus poles to reduce end-use emissions.