Management of this province?s forest resources must include not only social values such as employment, recreation opportunities and cultural integrity, be ecologically grounded to provide a continued supply of timber without compromising important qualities such as high levels of biodiversity, but also be economically feasible. New policy initiatives require rigorous scientific knowledge to demonstrate they will meet SFM (sustainable forest management) objectives in all forest regions of this province
The project?s objective(s) is to determine the density of broadleaf stems (basal area too) that maximizes complex stand productivity, minimizes costs associated with achieving free-growing objectives, models growth and development of complex stands, and ascertains optimal (cost-benefit) treatment regimes to enhance stand productivity and species and structural diversity. This provides a basis for a more strategic approach to brushing programs: allocating activities to areas where vegetation control is necessary and avoiding treatment of areas where current broadleaf densities will not impact conifer growth or where a mixedwood complex stand is an appropriate and desirable future forest condition. One significant result of this approach is there will be less herbicide usage at the landscape level.
The latest Dawson Creek Timber Supply Review (TSR) of the timber supply area (TSA) (1) identified the need to manage mixedwood stands to maintain their attributes on the landscape ? to stop ?unmixing the mixedwood? forest. It has been suggested that the productivity of mixedwood stands is greater over the long term than single species or conifer regenerated stands (2, 3, 4). It has also been suggested that species mixtures (aspen-spruce, birch-spruce) result in greater merchantable wood volumes than stands with only one of the species and that some benefits of natural stand dynamics may be realized by managing for complex mixtures. However the current operational ?default? of eliminating most or all broadleaf tree species is costly, reduces species and structural diversity, and in many instances may not be needed (5, 6, 7).
The cost of carrying out some brushing treatments to meet free-growing guidelines in much of the province may be unwarranted when treatment benefits are measured. As part of the Adams Lake Interfor Innovative Forest Practices Agreement (6), studies showed the cost of brushing birch from blocks planted to lodgepole pine may be greater than the anticipated increase in crop tree value (incremental growth): a negative investment. Current free-growing guidelines (7) require the removal of deciduous competition despite evidence suggesting that it is not cost-effective, and does not typically result in higher timber volumes or better wood quality. In fact, wood quality may be compromised: slower crown lift and larger branches.
Complex or intimate mixtures are seldom managed for, and when managed, tend to be managed poorly. The 2002 Dawson Creek TSR identified a gap in management of northern complex stands, and the Chief Forester stated that if these stands were not managed, they would be removed from the timber harvesting land base and hence the allowable annual cut (1). The absence of management is probably due to a limited understanding of the dynamic processes in complex stands and a lack of models (growth and yield and successional). There is limited quantitative information available on how complex stands develop during early seral stages and how early stand composition translates to future forest condition, and what the short- to long-term growth and yield implications may be.
A better definition of how biological values and economic considerations interact will lead to reduced brushing costs (manual or chemical treatments), and an increase in stand-level and landscape-level species and structural diversity. However, the impacts of less brushing on growth and yield and future timber supply are not ...