Changes in timber haul emissions in the context of shifting forest management and infrastructure

Transport-related emissions, evaluated as a fraction of transported wood carbon at 4 points in time on a landscape in western Montana (USA), rose from 0.5% in 1988 to 1.7% in 2004 as local mills closed and spatial patterns of harvest shifted due to decreased logging on federal lands.The apparent sensitivity of transport emissions to harvest and infrastructure patterns suggests that timber haul is a dynamic component of forest carbon management that bears further study both across regions and over time. The monitoring approach used here, which draws only from widely available monitoring data, could readily be adapted to provide current and historical estimates of transport emissions in a consistent way across large areas.Significant amounts of carbon may be stored in harvested wood products. In the United States, for example, removals of atmospheric carbon due to changes in forest product pools are currently on the order of 50 Tg C per year [1,2]. However, the management activity needed to transfer ecosystem carbon to product pools usually involves the release of carbon from fossil fuels. The transport of timber from the stand to processing facilities may be a particularly important source of fossil carbon emission. Such transport can represent more than 50% of all fossil carbon emissions related to forest management [3,4]. Sonne [5] estimated that timber transport in 50-year rotation Douglas-fir forests released carbon dioxide equivalent to 4.8% of stand storage. While timber transport may represent a significant "cost" of sequestering carbon in harvested wood products, the magnitude of haul emissions will clearly vary in relation to the distance timber must travel to reach milling facilities.To date, logistical obstacles have prevented comprehensive tracking of timber transport distances and emissions. While average road distances can be tracked by individual drivers and/or mill operators, record-keeping at the landscape level would be onerous. Existing efforts to