The Timber Harvesting Land Base (THLB) is an estimate of the land where timber harvesting is considered both acceptable and economically feasible, given the objectives for all relevant forest values, existing timber quality, market values and applicable technology. It is a theoretical, strategic-level estimate used for timber supply analysis and could include areas that may never be harvested or may exclude areas that will be harvested.

A timber supply review (TSR) determines the Timber Harvesting Land Base. The last full timber supply review (TSR 3) for the Soo Timber Supply Area was completed in 2011.

The 2021 THLB data is a modified version of TSR3, updated to reflect changes to the landbase since the last TSR. The most significant change is the removal of large area-based tenures, specifically the Lilwat Woodland Licence (N2V) and Pemberton community forest (K5X).

When the next TSR occurs, a new THLB will be established based on the most current land management regime and legislation.