A Life Cycle Analysis of Forest Carbon Balance and Carbon Emissions of Timber Harvesting in West Virginia

A life cycle inventory framework of "cradle to gate" combined with Monte Carlo stochastic simulation was used to analyze the forest carbon balance and emissions from mechanized and manual harvesting operations from 2000 to 2009 in West Virginia. Mechanized and manual harvesting operations were compared on the slope of the sites ranging from 10 to 35% where average diameter at breast height of harvested trees was 40.64 cm. The results showed that the annual carbon balance of the forests per hectare was not significantly affected by carbon loss from the removal of sawlog volume (or timber), fire, and limited dead trees, until tree mortality and/or harvesting intensity reached a high level. Additionally, it was found that average carbon emission from fossil fuel consumption was 5.06 ± 0.90 metric tons per thousand cubic meters (Mg/TCM) of timber produced for a manual harvesting system and 6.84 ± 1.22 Mg/TCM for a mechanized harvesting system. Approximately 1.71 and 2.31% of the stored carbon in processed lumber would be displaced by harvesting emissions, respectively, for manual and mechanized systems. The forest carbon displacement rate during timber harvesting was affected largely by hauling process, while felling, processing, skidding, and loading processes had smaller impacts. Among the harvest processes studied, uncertainty of carbon emissions from fuel consumption and forest carbon displacement rate could be attributed to hauling distance, payload size, forest type, and machine productivity.