Diesel Consumption and Carbon Balance in South African Pine Clear-Felling CTL Operations: a Preliminary Case Study

Recent and increasing use of mechanized cut-to-length (CTL) operations in South Africa has been associated with greater diesel and lubricant requirements than was previously the case with motor-manual or semi-mechanized activities, placing a strain on the environmental and economic sustainability of operations. This case study explores diesel and lubricant consump- tion of a typical CTL pine saw timber operation, taking into account the stand and terrain factors, with the aim of setting baselines for these consumption rates as well as carbon emis- sions. Data analyzed was provided by Bosbok Ontginning, a contractor based in Mpumu- langa, throughout their clear-fell operations over the 49 compartments from May 2014 to June 2015. The mean diesel consumption rate was found to be 0.64 l m-3 and 0.38 l m-3, while the lubricant consumption was 0.08 l m-3 and 0.03 l m-3 for the harvester and the forwarder, re- spectively. Carbon emissions from diesel were found to account for less than 1% of the carbon stored in the harvested timber. Statistical analysis showed that tree size, stand density and ground condition were not significant predictors of either diesel or lubricant consumption. Prior research suggests that other factors not included in this study (i.e. machine character- istics, operator habits and productivity) may have a more pronounced effect on diesel consump- tion. Future studies should therefore be conducted to analyze these factors within South Afri- can conditions as well as explore stand and terrain conditions more specifically and over more diverse stand and terrain conditions as well as machine types.