Canadian Forest Service Publications

Risk assessment of the threat of mountain pine beetle to Canada’s boreal and eastern pine resources. 2008. Nealis, V.G.; Peter, B., compilers. Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Victoria, British Columbia. Information Report BC-X-417. 38 p.

Year: 2008

Available from: Pacific Forestry Centre

Catalog ID: 28891

Language: English

Series: Information Report (PFC - Victoria)

CFS Availability: Order paper copy (free), PDF (download)

Abstract

This report assesses the threat of mountain pine beetle (Dendroctonus ponderosae Hopkins) to Canada's boreal and eastern pine forests. It is based on available evidence and expert advice provided by researchers and forest managers at two workshops held in Edmonton, Alberta and Victoria, British Columbia during August and September of 2007.

The main findings include:

Recent spread of the mountain pine beetle outside its historical range is a consequence of both persistent short-distance diffusion and occasional long-distance dispersal of adult beetles from epidemic populations in British Columbia. These immigrants have successfully reproduced and thus are in the early stages of range extension.

There are no evident host-related impediments to the spread of mountain pine beetle further east or north through the boreal zone as dominant boreal and eastern pine species are suitable hosts for both the mountain pine beetle and associated blue-stain fungi.

Forest structure (e.g., age-class distribution, size and spatial distribution of host trees) in the boreal forest is less likely to favour the same high rates of spread and severe levels of damage observed in the denser, older and larger pine forests of the interior of British Columbia.

Weather conditions of the past decade have facilitated the survival of mountain pine beetle in its expanded range but climate conditions in these regions are still relatively unfavourable, reducing the short-term risks of mountain pine beetle epidemics spreading rapidly across the boreal region. In the near future, the area of climatic suitability is expected to increase in British Columbia and northwest Alberta, especially toward the Yukon and Northwest Territories. In the more easterly portions of the boreal zone, the area of climatic suitability will decrease slightly and shift northward.

Natural extinction of the mountain pine beetle in its expanded range is unlikely. More likely is persistence of populations outside the historical range. Even if population levels remain low, the expanded range of the beetle could create an ecological pathway across the prairie region that allows for continuing spread of the insect further east into more susceptible pine forests. Wherever suitable conditions exist within this expanded range, there is the potential for damaging outbreaks and accelerated spread.

If mountain pine beetle outbreaks occur in the boreal zone, a reduction of timber supply from affected regions will result. Stand-level losses in terms of absolute volumes are unlikely to be as severe as those experienced in British Columbia but could still render some stands inoperable. Net economic impacts will depend heavily on the extent and timing of tree mortality and the concurrent demand for timber by the forest sector. Regulatory impacts (e.g., log transport restrictions) and changes to fibre flows may reduce operational efficiency. Trends in other resource and industry sectors will affect the capacity for communities to adapt to mountain pine beetle-related impacts on the forest sector.

Boreal and eastern pine forests provide non-timber benefits to society. As a result of the relatively smaller scale of the forest sector in the prairie region, impacts of mountain pine beetle damage on these non-timber values may have greater significance in this region than in British Columbia. Forest management interventions may come into conflict with these non-timber values in some locations. The cost of disposing of dead-standing pine where its presence is incompatible with other values (e.g., safety concerns in public campgrounds) may also create financial impacts.

Additional fire risks and increased uncertainty of future fire behaviour will result from damage.

Doing nothing in response to the incursion of mountain pine beetle would exceed the risk tolerance of stakeholders in the regions under threat. A response based on current information and knowledge should include both short-term direct control and longer-term preventative management. A comprehensive response will require a variety of management actions based on objectives specific to local outbreak conditions, stand vulnerability, values at risk, and operational feasibility.

Uncertainty over the effectiveness of management responses to the risks posed by mountain pine beetle may be reduced by addressing the information gaps identified in this report. These include refining methods used in mountain pine beetle monitoring and detection and improving information on current forest cover in areas without a forest management inventory. The most critical immediate information need is for effective mountain pine beetle monitoring and detection in areas vulnerable to the current infestation. Research priorities include enhancing knowledge of suitability of other pine species to mountain pine beetle and associated fungi, climatic suitability, and models and tools to predict mountain pine beetle dispersal, fire behaviour, economic impacts, and community adaptation strategies.

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