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Figure 7. Blister-like structures on the stem of a white pine infected with blister rust. (Photo: S. Greifenhagen)
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| Figure 8. White pine weevil larvae. (Photo: S. McPherson) |
Challenges to increasing the abundance of white pine in the Lake Abitibi and Lake Temagami ecoregions include:
- Reduced seed sources: The historical depletion of white pine on the landscape has reduced its abundance. Fewer white pine trees means fewer white pine seeds, both for natural regeneration and for producing white pine seedlings in nurseries to plant on harvested sites.
- Diseases and insects: White pine blister rust remains a major obstacle to restoring white pine on the landscape. White pine blister rust infects white pine trees of any age, but it is most damaging to young seedlings growing in the open. Infection of white pine by the rust causes lesions to form (Figure 7) and can potentially kill young white pine trees. The cool and moist late summer climate in northern Ontario favours white pine blister rust on most sites.
- White pine weevil is a native insect that feeds on and kills the terminal shoots of young white pines, especially those growing in full sunlight (Figure 8). A prominent stem crook forms as one of the living side branches takes over to become the main stem. Damage by weevil rarely results in mortality but can reduce tree growth and future wood quality.
- Fire suppression and competing vegetation: If not adequately controlled, competing vegetation can strongly limit the survival and growth of young white pine. Without fire, early and effective silvicultural treatments to control competing vegetation are essential for the successful regeneration of white pine after harvesting, particularly on more fertile sites.
- Economics of white pine silviculture: Timely silvicultural treatments can overcome the factors mentioned above. However, these treatments can be expensive. Appropriate site selection and good planning are essential for regeneration to be economically feasible. As well, forest managers may be reluctant to invest in white pine silviculture when the probability of the success of silvicultural treatments is uncertain or where local demand for its wood is low. However, by 70 years of age, white pine stands on favourable sites will out-produce all other commercial tree species in Ontario, both in wood volume and economic value. Investment in white pine silviculture therefore has long-term economic benefits.
Silviculture is applied forest ecology. It is the art and science of regenerating, tending, and maintaining forest stands. The cost of silviculture is weighed against the potential economic return from the many forest products produced.
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Current management of the resource
