Age class structure
The Forest Service analysis indicates that 77 per cent of the land base is composed of mature forests. Of these mature forests, fifty-two per cent are lodge pole pine forests. The Merritt Forest Licencees assert that the current age class structure and the structure in 50 years are cause for concern.
The Merritt Forest Licencees maintain that the high proportion of mature forests increase the risk of timber volume losses due to insects, disease, fire and windthrow. They suggest the current level of harvest may not accommodate future increases in salvage harvesting.
The Interior Lumber Manufacturers' Association also expresses concern about the number of mature forests in the Merritt Timber Supply Area. They state that the long term sustainability of timber supply is at "significant risk".
Site index estimates
Site index is a measure of the ability of an area to produce trees. The Merritt Forest
Licencees suggest that site indices derived from existing forests underestimate the site indices of future managed forests. The underestimation of replacement forest productivity reduces potential volume and overstates the time required to achieve "green-up" and mature height.
A submission from the Interior Lumber Manufacturers' Association also suggests that the site indices used in the Forest Service analysis underestimate future growth and volumes for areas harvested and reforested.
The Merritt Forest Licencees made a number of other points regarding the analysis of inventory information, including:
• mature volume estimates are reasonable, but could possibly be higher
• the managed forest equations for existing and future regenerated forests are appropriate
• the estimate of 84 years as a minimum harvest age is acceptable. In the future, minimum volume and diameter should be decided in conjunction with the Merritt Forest Licencees
• the operational adjustment factors of 15 per cent and five per cent used in the analysis are conservative
