Management of the Mountain Pine Beetle
Measures for controlling the mountain pine beetle occur throughout the year. However, the insect's biology and the local climate determine when specific activities can be implemented. Further, the timing of some activities must coordinate with subsequent activities. For example, probing must precede harvesting but must be carried out early enough that priority stands can be harvested before the next insect flight period.
Setting Management Priorities
Not all forested lands with mountain pine beetles require management. Numerous factors are considered first, including susceptible pine volumes at risk; beetle population size; access for harvesting; slope; other resource values; and, treatment resources.
The land base is divided into smaller “beetle management units" (BMUs), usually along landscape unit boundaries. BMUs are used to set management objectives and treatment targets.
- Suppression BMUs are the most intensively managed; the objective is to treat at least 80 per cent of the known beetle infestations before the next beetle flight period
- Holding Action BMUs have a target of 50 to 80 per cent treated
- Salvage BMUs are primarily for recovering value from recently killed timber
Detection & Survey
Beetle management requires two stages of detection: 1) aerial surveys and 2) ground surveys. Surveillance-level aerial survey information is collected using the provincial aerial overview survey which serves to record the beetle damage at a low resolution and also identify new areas of attack. More detailed heli-GPS aerial surveys provide the spatial accuracy to direct ground crews to newly faded “red attack” trees to be surveyed.
Two types of ground surveys are used: walkthroughs and probes. They differ in intensity, quality and quantity of data collected. Both are necessary to confirm information gathered from aerial surveys.
- Walkthroughs are non-systematic preliminary ground reconnaissance surveys
- Probes are systematic, detailed surveys used to more accurately locate and quantify currently attacked trees for follow up treatments
This can include:
Baiting — the use of aggregating semiochemicals (pheromone baits). Must always be followed by actions to remove or eradicate the concentrated beetle populations. Baiting is used to improve the efficacy of harvesting and single-tree treatments.
Harvesting — the most efficient short-term method of dealing with mountain pine beetle populations where appropriate and practical. In all cases, the intent is to remove as much infested material as possible before the next beetle flight while meeting management objectives.
Single-tree treatment — requires detailed detection surveys. Treatment is intended to destroy beetles in individual infested trees, thereby reducing the beetle population available to infest new trees. Success depends on timing and method of application. Thoroughness is required. Monitoring and possible re-treatments are necessary.
Most treatments will have to be repeated each year that the strategy remains in place. Unless the nature of the forest is changed, the susceptibility, and often the risk of subsequent infestation, will be similar from year to year.
Hazard and risk rating
Hazard rating identifies stands where substantial losses can be expected if an outbreak occurs. For mountain pine beetle it requires forest inventory data and inventory polygon location information. Data are collected from prism plots in the field to calculate the hazard index. Stands should be considered a high priority for hazard rating and management if they contain a high proportion of lodgepole pine 60 years and older and have elevation, latitude and longitude codes equal to high.
Risk rating estimates the probability of an outbreak arising, depending on a stand's proximity to an existing beetle population. It's determined by overlaying detailed sketch mapping and available ground detection results.