Operational adjustment factors (OAF) are used to account for gaps or holes within stands as well as the effects of volume loss on older stands. What is commonly referred to as OAF 1 is the percentage of the land base that can be assumed to be made up of unproductive gaps in the canopy within stands. Its effect is a decrease in the magnitude of the yield curve, not the shape of the yield curve. On the other hand, OAF 2 is the gradual percentage reduction in yield due to mortality caused by biotic and abiotic damage, waste and breakage, as well as the effects of species mixes. Its effect is a change in the shape of the yield curve; essentially a lowering of the tail end of the curve. Operational adjustment factors play an important role in timber supply analysis. Since they account for a land base net-down of up to 15% (provincial guideline for OAF 1) when local information is not available, it is important to determine an OAF value that is truly representative to a specific land base. Depending on the leading species, growth characteristics, and forest health conditions, localized OAF 1 values can either be close to the provincial applied average value, or significantly lower or higher. Localized OAF 1 values are often influenced by the ITG (inventory type groups) and their typical stand characteristics present across a land base.
Timberline Forest Inventory Consultants.
Timberline Forest Inventory Consultants Ltd.. 2004. Vanderhoof IFPA operational adjustment factor (OAF 1): localization final report -- revised. Forest Investment Account (FIA) - Land Base Investment Program - Innovative. Forest Investment Account Report