B.C. forest industry starts to look at commercial thinning—by necessity

By Jim Stirling

British Columbia’s forest industry tends to apply silvicultural techniques only when forced. Now is one of those times.

The wood supply issues are critical enough to persuade forest companies to take a serious look at the implications of commercial thinning in newer generations of merchantable trees contained within their forest licences. Thinning a maturing forest stand is viewed as one way of accessing additional fibre. Commercial thinning techniques might also help mitigate the mid-term fibre supply challenges.

The reasons for the shrinking wood supply have been well documented. The most obvious recent ones being fibre losses from the prolonged mountain pine beetle epidemic in the B.C. Interior and fibre losses to wild fires, both phenomena exacerbated by the warming climate. The effects of the diminishing wood supply have been similarly well documented: permanent closures of sawmills and other wood processing plants; shift reductions and temporary closures in those that remain and the residents in many communities worried about their immediate futures.

Canfor, West Fraser and Carrier Lumber are among the growing number of companies taking a serious look at applying commercial thinning techniques on appropriate stands in B.C.

They are following a route well travelled. Back in the early-1970s, Sweden used its Elmia wood exhibition as an international exchange of information to help explore commercial thinning issues and generate solutions to problems. The Swedes, like forest companies operating now in B.C., began investigating thinning methods because the Swedish forest industry also needed the wood fibre source potential offered by commercial thinning, albeit for different reasons.

It was no surprise to the Swedes to confirm commercial thinning harvesting costs are considerably higher than those associated with clearcutting. They also quickly discovered that selective thinning techniques were more advantageous to the remaining stand from a biological point of view than geometrical thinning, where the process follows corridors or rows. But the flip side was selective thinning cost more to design and implement.

The main issue with selective thinning techniques is removing the desired stems while minimizing damage to the remaining stand. The working environment is narrow and restrictive. The standing stems get in the way, reducing sight lines and limiting machine boom movements. Winching out stems selected for removal demands more labour, and its effectiveness is influenced by snow conditions. The Swedish research concluded a new approach was required to commercially thin a stand most effectively, one specifically designed for operating in the restricted environment.

It’s interesting because the basic elements are the same as in a clearcut scenario. Trees need to be felled, delimbed and processed and the stems removed. It’s the scale that’s different. The trees are smaller than in a typical clearcut situation, affecting processing efficiency—and the working environment tighter. And add in, of course, the need to avoid damaging the residual stand and its root systems while keeping operating costs within limits.

The Swedish researchers began looking at different designs and configurations of smaller, purpose-built and multi-function machines. Some resembled a combination of a wheeled forwarder with on-board harvesting and processing capabilities.

Much has changed since the 1970s, of course. The knowledge and data gathering about the effects and costs of varying thinning systems on the remaining environment have been collected and analyzed. The experience with thinning systems in Scandinavia and other European countries with forest industries can only help Canadian forest companies. Conditions might vary considerably but the basic premises surrounding commercial thinning systems are as applicable to southern Sweden as they are to central B.C.

It all means entering the higher cost world of mechanized commercial thinning is much easier today for Canadian forest companies. It’s akin to when mechanized harvesting machines were introduced to North America. Most of them had a purpose-built European pedigree. In many cases, a period of machine reconfiguration and adjustment was needed to fit Canadian operating conditions. But the transitions were successfully made.

Selecting the most appropriate sites for commercial thinning will be an early and essential part of the learning curve for B.C. companies. Which stands will prove the best candidates for commercial thinning? How can they best be laid out and designed to contain costs as much as possible while meeting the forest company’s expectations for the amounts and quality of the wood extracted?

Today’s designers of commercial thinning machines have a sound idea of the machines’ operational requirements—there is already equipment out there, harvesting machines and heads, designed for small diameter stems. The demand side of the equation might prove to be a bit more of an unknown. Manufacturers can only make educated projections about the demand for commercial thinning equipment. It also seems likely that during the initial period of commercial thinning in B.C., the equipment manufacturing maestros will test some prototype versions. They have proved very adept at the process as other generations of forest harvesting machines have matured.

Although unusual circumstances have combined to create the necessity of interest in commercial thinning techniques, they may well prove to have an accepted role in forest management. In Finland, for example, thinnings are considered an unavoidable part of the silvicultural care of a stand during its rotation period. Therefore, thinnings are not a separate problem but part of the system of growing stands and logging.