As part of the provincial Timber Supply Review, the British Columbia Forest Service has examined the availability of timber in the Kamloops Timber Supply Area (TSA). The analysis assesses how current forest management practices affect the supply of wood available for harvesting over the next 250 years. It also examines the potential changes in the 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. This report does not include an analysis of the potential timber supply impacts of timber harvesting requirements under pulpwood agreements in the Kamloops TSA.
The Kamloops TSA consists of approximately 2.12 million hectares of which about 900 000 hectares are considered available for timber harvesting under current management assumptions. The area available for timber harvesting is dominated by stands of lodgepole pine, spruce, and Douglasfir. The current AAC for the Kamloops TSA is 2 393 180 cubic metres per year, which excludes the volume allocated to woodlot licences and volumes currently being harvested in decadent cedar and hemlock stands.
Given current forest management assumptions and timber volume estimates, the analysis results indicate that the current harvest level can be maintained for 20 years. The harvest rate then drops by 9% per decade, reaching the longterm harvest level of 1 958 000 cubic metres per year, 18% below the current harvest level, in 40 years.
Several factors may affect the base case timber supply forecast in the short term. Immediate reductions in the current harvest level may be required if existing stand volumes are lower than was estimated, greenup forest cover requirements are more restrictive, the amount of time trees require to reach greenup heights is longer, or if minimum harvestable ages are longer than in the base case.
While approximately 60% of the Kamloops TSA timber harvesting land base contains stands of mature timber, a significant portion is currently unavailable for harvest because forest cover within the area being managed for visual quality (the landscape management zone) does not currently meet visual quality objectives. This zone comprises 22% of the timber harvesting land base and contains 24% of the mature timber. The first 20 years of harvest, therefore, must come almost entirely from the remaining land base. Increasing the maximum allowable area that does not meet visual greenup requirements within the landscape management zone by 5% would allow the current harvest level to be maintained for an additional 20 years, and increase the longterm harvest level by 7%.
Increases in timber supply over the next few decades that could allow for an extension or increase in the current harvest level may result if, compared to the base case: minimum harvestable ages are shorter; existing stand volumes are greater; the amount of time trees take to reach green-up heights is shorter; the timber harvesting land base is larger; or if decadent, overmature hemlock volumes are included within the existing stand yield curves.
The longterm harvest level is most sensitive to uncertainties about managed-stand volume estimates, the length of time required to reach greenup heights, the amount of area required to meet greenup forest cover requirements, and the amount of area in the timber harvesting land base.
An approximation of the Kamloops Land and Resource
Management Plan (LRMP) of December 1994 planning team recommendations
showed that the initial harvest level could be maintained for
1 decade and that the longterm harvest level would
increase by about 1% compared to the base case.