Regional carbon dioxide implications of forest bioenergy production

Policies are being developed worldwide to increase bioenergy production as a substitution for fossil fuel to mitigate fossil fuelderived carbon dioxide emissions, the main cause of anthropogenic global climate change4,5. However, the capacity for forest sector bioenergy production to offset carbon dioxide emissions is limited by fossil fuel emissions from this activity (harvest, transport, and manufacturing of wood products) and the lower energy output per unit carbon emitted compared with fossil fuels6. Furthermore, forest carbon sequestration can take from decades to centuries to return to pre-harvest levels, depending on the initial conditions and amount of wood removed7. The effects of changes in management on CO2 emissions need to be evaluated against this baseline. Consequently, energy policy implemented without full carbon accounting and an understanding of the underlying processes risks increasing rather than decreasing emissions4,8. InNorthAmerica, there is increasing interest in partiallymeeting energy demands through large-scale forest thinning5, with the added benefit of preventing catastrophic wildfire and concurrent carbon loss3. Although forest thinning can be economically feasible, sustainable, and an effective strategy for preventing wildfire where risk is high9,10, it remains unresolved whether this type of forest treatment can satisfy both the aims of preventing wildfire and reducing regional greenhouse gas emissions. For both aims to be satisfied, it needs to be shown that: (1) reduction in carbon stocks due to thinning and the associated