Harvest volumes and carbon stocks in boreal forests of Ontario, Canada

We used models to project forest carbon stocks for a series of harvesting scenarios for 29 boreal forest management units totalling 23.3 million ha in Ontario, Canada. Scenarios evaluated for 2020 to 2050 ranged from a no harvesting option to annual harvesting of 2% of the total merchantable volume present in 2020. For each scenario, we estimated the following carbon quantities: (a) forest ecosystem carbon stocks, (b) sum of carbon stocks in forest ecosystem and harvested wood products (HWP) minus emissions associated with HWP production and decomposition, and (c) net greenhouse gas (GHG) effects of harvesting estimated as (b) combined with emissions avoided by substituting HWP for non-wood materials. The average of each carbon quantity for 2020 to 2050 was linearly dependent on the annual harvest volume. The developed relationships were used to estimate harvest volumes for which the three carbon quantities would equal equilibrium forest ecosystem carbon stocks for a pre-suppression natural disturbance cycle. These estimates indicate the range of harvest volumes for which resulting carbon stocks would equal or exceed those in an unmanaged forest. Also discussed are possible criteria for determining annual harvest volume.