Identifying the Optimal Season to Harvest Firewood in Interior Alaska to Significantly Reduce Drying Time

Residents in cold climates, such as Fairbanks, Alaska, use firewood to heat homes to reduce energy costs. Many residents burn “green” firewood with moisture content (MC) greater than 20 percent because they burn it too soon after harvest, which results in severe winter pollution from fine particulate matter production. The community would benefit from harvest guidelines that reduce drying times and the burning of green wood. This study identified optimal harvesting times and the roles of live tree MC and climate conditions on the drying process. Spruce and birch trees were harvested to capture the highest variability in seasonal MC before snowmelt (March), 2 weeks after leaf out (May), mid- to late growing season (July), and before freeze-up after autumn (September/October). The wood was split and stacked on load cells under a wood shelter to monitor weight (water) loss to 20 percent MC. Tree MC at harvest had no effect on drying times. Harvesting in late May produced the shortest drying times (2.1 to 2.2 mo), followed by March (3.5 to 4.2 mo) due to overlap with warm, dry conditions early in the drying process. The September/October and July drying times were longer (9.4 to 10.5 mo) due to cold and humid conditions early in the drying process. The large amount of water lost in the first month of warm, dry climate conditions showed the significance of splitting and stacking wood immediately after harvest. The value of this study for informing the region’s public firewood practices is discussed.