As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Kingcome Timber Supply Area (TSA). The analysis assesses how current forest management practices affect the supply of wood available for harvesting over the both the short (next 20 years) and long (next 250 years) term. It also examines the potential changes in timber supply stemming from uncertainties about forest growth and management actions. It is important to note that the various harvest forecasts included in the report indicate only the timber supply implications of current practices and uncertainty. As such, the forecasts should be used for discussion purposes only; they are not allowable annual cut (AAC) recommendations.
The Kingcome TSA consists of a total of about 1.13 million hectares of land on both northern Vancouver Island and the mainland coastal area between the Mid Coast, Strathcona and Sunshine Coast TSAs. About 178 000 hectares of the Kingcome TSA is considered available for timber harvesting and production under current management practices. The area is dominated by hemlock, balsam and cedar forests, with a small amount of Douglasfir and Sitka spruce.
The AAC for the Kingcome TSA totals 1 798 270 cubic metres per year, which includes an allocation of 139 500 cubic metres per year for harvesting of deciduous stands, low quality sites and woodlots. For the timber supply review only conventional conifer harvesting was assessed. Therefore the AAC used for this analysis is 1 658 770 cubic metres per year.
The results of this timber supply analysis suggest that the current AAC in the Kingcome TSA cannot be maintained for even one more decade without causing severe timber supply shortfalls in the future. Using current forest inventory and timber growth information, and assuming continuation of current forest management practices, an initial harvest of 1 068 600 cubic metres per year can be attained. This is 35% below the current AAC used for this analysis. After the first decade the harvest decreases 10% per decade until decade 4 when it reaches its lowest point of 779 000 cubic metres per year. This level is maintained until decade 15 when the harvest level begins to rise toward the longterm harvest level. The harvest level that is sustainable over the long term 902 600 cubic metres per year is reached in 160 years.
The shortterm harvest levels are significantly impacted by the forest cover guidelines for visual quality and adjacency. However, it is important to note that even if the forest cover guidelines were not in place the initial harvest level would still be lower than the present AAC and the decline to the longterm harvest level would have to start immediately after the first decade. In fact, harvesting history combined with the current forest cover guidelines and management regime result in a maximum initial harvest level of 1 496 300 cubic metres per year. However, if this level is harvested, the second decade harvest falls to 610 500 cubic metres per year.
It was not possible, given current management
assumptions, to develop a harvest forecast that does not fall
below the longterm harvest level. Three main factors contribute
to the projected trough and the initial harvest level. First,
insufficient mature inventory exists to maintain harvests above
the longterm level. The maximum longterm harvest
level is attained after currently young stands reach a harvestable
size. In addition the forest cover guidelines for visual quality
and adjacency are a recent change in management practices which
contribute to the decline in timber supply. Past harvesting history
and patterns have resulted in a large amount of forest initially
younger than the greenup ages in all management zones.
In fact, currently the retention visual quality objective (VQO)
and the modification VQO areas have more than double the maximum
area allowed below the required greenup age. The third
cause of the trough during decades 4 to 16 is the expectation
that managed stands will produce higher volumes per hectare than
the present natural stands; this increases the apparent shortfall
by raising the longterm harvest level.