If you take a look at this picture, you will notice that the majority of the trees are their natural, beautiful and healthy green colour. However, there are a few trees on the left that are brown. They look dead. This, ladies and gentlemen, is what tree looks like after it has been infested with the Mountain Pine Beetle. If you have traveled, well, anywhere in BC, you will have seen trees ravaged by this beetle. Here are some facts, courtesy of the BC Ministry of Forests and Range:
Beetle Biology
- The Latin name for the
mountain pine beetle is Dendroctonus ponderosae.
- The life span of an individual mountain pine beetle is about one year.
- Pine beetle larvae spend the winter under bark. They continue to feed in the spring and transform into pupae in June and July.
- Adult mountain pine beetles emerge from an infested tree over the course of the summer and into early fall.
- The mountain pine beetle transmits a fungus that stains a tree's sapwood blue.
- Comprehensive testing has confirmed that the blue stain caused by the beetle has no effect on wood's strength properties.
Contributing Factors
- The mountain pine beetle prefers mature timber. After 80 years, lodgepole pine trees are generally classed as being mature.
- B.C. is believed to have three times more mature lodgepole pine than it did over 90 years ago, mainly because equipment and techniques for protecting forests against wildfire have greatly improved over time
- Hot and dry summers leave pine drought-stressed and more susceptible to attack by the mountain pine beetle.
Beetles and Cold Weather
- Cold weather kills the mountain pine beetle. Mountain pine beetle eggs, pupae and young larvae are the most susceptible to freezing temperatures.
- In the winter, temperatures must consistently be below -35 Celsius or -40 Celsius for several straight days to kill off large portions of mountain pine beetle populations.
- In the early fall or late spring, sustained temperatures of -25 Celsius can freeze mountain pine beetle populations to death.
- A sudden cold snap is more lethal in the fall, before the mountain pine beetles are able to build up their natural anti-freeze (glycerol) levels.
- Cold weather is also more effective before it snows. A deep layer of snow on the ground can help insulate mountain pine beetles in the lower part of the tree against outside temperatures.
- Wind chill affects mountain pine beetles, but is usually not sustained long enough to significantly increase winter mortality.
Infestation Information
- The Ministry of Forests and Range estimates that the mountain pine beetle has now killed a cumulative total of 620 million cubic metres of timber since the current infestation began.
- The cumulative area of B.C. affected to some degree (red-attack and grey-attack) is estimated at 14.5 million hectares.
- 14.5 million hectares is more than four times the size of Vancouver Island.
- Newly attacked trees turn red about one year after infestation. Trees can stay in the red-attack stage for two to four years before turning grey as they lose their needles.
- On a provincial level, the infestation has peaked and is now slowing down.
- 7.8 million hectares of red-attack were surveyed in 2008.
- This is compared to 10.1 million hectares the year before. This is the first decrease in red-attack since the current infestation began.
- The amount of habitat available to the beetle has begun to diminish as the beetle has already attacked most of the mature lodgepole pine in the Central Plateau region.
- The rate of spread in other areas of the Interior has been slowed by more diverse terrain and forests with a greater diversity of timber species.
- The mountain pine beetle in B.C. is as far-ranging as Fort St. John to the north, the Alberta border to the east, Terrace to the west, and the United States border to the south.
On my last two trips up the Coquihalls highway and heading down into Merritt it absolutely breaks my heart to see a sea of red rolling over the hills, as opposed to the traditional stunning forest green. I remember over four years ago first really noticing the effect that the pine beetle was taking on a trip up to the Skeena region. Each year it has gotten worse and worse, especially through the Kamloops and Cariboo regions, and the landscapes around our favoured lakes has been scoured from dead tree removal, with the stumpy carcasses of once majestic trees dotting the shorelines. Click on this map to see the extent of the damage in BC:
The David Suzuki Foundation also has some good information on the Mountain Pine Beetle, with a slightly more positive take on the effects of the infestation. Good food for thought.
2 comments:
Very interesting story. At the first glance I thought this is another victim of invasive species... but after reading some related information, it appears this is a native species with a side effect of climate change. Interesting read! I found the following info from the website convey some important message....we got to watch out those logging intended people to use the beetle as an excuse...
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" A paper published by University of Oregon scientists in 2001 suggests that the productivity and health of forests actually benefit in the long-term from the impact of insect outbreaks. Ecosystem-based management, which would selectively remove trees if any logging was deemed beneficial, keeps the beetle population at its natural level and helps prevent epidemic levels.
It is important to understand that mountain pine beetle, and other bark beetles, are native species and a ubiquitous feature of many forests, including those in the BC interior. These beetles are present everywhere lodgepole pine is a significant component of the forest, and they are a natural and essential elements of the forests. Beetle-killed trees provide vital ecological services and functions even when they are dead, such as nesting and roosting habitat for woodland birds, food sources for beetle predators, and nutrient cycling.
Given these important functions, the current rhetoric in British Columbia about the "war against the beetle" is inappropriate. Extensive clearcutting in affected forests will not control the present outbreak. The purpose of any 'salvage' logging is to remove and process dead timber before the wood is so degraded that it has no market value. This differs from logging affected forests in an effort to reduce beetle abundance where broods are still present. "
Nice blog. Well done.
Doug in Memphis
http://dougsbugblog.blogspot.com
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