As part of the provincial Timber Supply Review the B.C. Forest Service has examined the availability of timber in the Kootenay Lake Timber Supply Area (TSA). The analysis assesses how current forest management practices affect the supply of wood available for harvesting over the next 200 years. 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 only indicate the timber supply implications of current practices and their associated uncertainty. The forecasts are to be used for discussion purposes only; they are not intended to imply any particular allowable annual cut (AAC) recommendations.
The Kootenay Lake TSA covers a total of 1.13 million hectares, of which about 297 000 hectares are considered available for timber harvesting under current management practices. The present AAC for the TSA is 900 000 cubic metres per year. The portion of the AAC currently administered in Kootenay Lake is 761 200 cubic metres per year. The remaining 138 800 cubic metres has not been allocated to any licence.
Given current management assumptions, the analysis shows that the current AAC cannot be maintained without causing a sharp drop in future harvest levels. The maximum harvest in the first decade is 803 000 cubic metres per year, 11% below the current AAC. After the second decade, harvests must decrease 10% per decade until the long-term harvest level of 490 000 cubic metres per year is reached 70 years from now.
Initial harvest levels greater than 803 000 cubic metres per year result in a significant timber supply shortfall in the near future.
In most forecasts analyzed, the forest cover guidelines limit the amount of timber available for harvest in all management zones during the third and/or fourth decade. This results in the potential harvest level for the first 2 decades being controlled by the availability of timber in the third and/or fourth decade.
Many of the data and assumptions used in the analysis are subject to varying degrees of uncertainty. The Kootenay Lake Forest District staff are particularly concerned about the volume estimates for existing stands and the forest cover guidelines. Sensitivity analysis was used to determine how uncertainty about these and other data and assumptions affect the results of the timber supply analysis.
In the short-term, timber supply is highly sensitive to (1) lower yield estimates for existing stands and (2) tighter forest cover guidelines. For example, volumes which are 10% lower on existing stands result in a 26% decrease in the starting harvest level. Long-term harvest levels are also affected by these changes, but not to the same degree as short-term results.
Any changes that relax the forest cover guidelines or increase the yields on existing stands have only a low to moderate effect. The reason is that other constraints, such as minimum harvest ages and a desire for a reasonable rate of decline, begin to affect the harvest forecast much more than the forest cover guidelines do. Changes in regenerated yields have no effect on the short-term harvest rates, although the long-term harvest level is affected.
Meeting the management guidelines and constraints
used in the Kootenay Lake TSA requires a high degree of flexibility
in locating and scheduling harvests. Given the sensitivity of
the harvest forecast to changes in these guidelines, any attempts
to keep the harvest level at the base case starting level will
certainly reduce this flexibility and present a risk to the projected
harvest levels.