Everything about The Mountain Pine Beetle totally explained
The
mountain pine beetle,
Dendroctonus ponderosae, is a species of
bark beetle native to the forests of western
North America from
Mexico to central
British Columbia. It has a hard black shell and measures about 5 millimetres.
Mountain pine
beetles inhabit
pines, particularly the
Ponderosa Pine,
Lodgepole Pine,
Scots Pine and
Limber Pine. The
bristlecone pines and
pinyon pines are less commonly attacked. During early stages of an outbreak, attacks are limited largely to trees under stress from injury, poor site conditions, fire damage, overcrowding, root disease or old age. As beetle populations increase, the beetles attack most large trees in the outbreak area.
Tree infestations
The beetles kill the trees by boring through the bark into the
phloem layer on which they feed and in which eggs are laid. Pioneer female beetles initiate attacks, and produce pheromones which attract other beetles and results in mass attack. The trees respond to attack by increasing their resin output in order to discourage or kill the beetles, but the beetles carry blue stain fungi which, if established, will block the tree resin response. Over time (usually within 2 weeks of attack), the trees are overwhelmed as the phloem layer is damaged enough to cut off the flow of water and nutrients. In the end, the trees starve to death, and the damage can be easily seen even from the air in the form of reddened needles. Entire groves of trees after an outbreak will appear reddish for this reason. Usually older trees die faster. After particularly long and hot summers mountain pine beetle population can get out of hand and that's when there starts to be a problem. There are too many beetles and they start killing off big areas of trees.
Life cycle
Approximately two weeks following
oviposition, pine beetles hatch as white
larvae. They dig into tree bark where they spend the winter, then grow up to 7mm long in the spring. The
pupal stage ends in the late spring or early summer, and from mid-July to mid-August, the beetles leave their tunnels and fly to new trees. Female beetles release
pheromones to attract males and encourage mass attacks. The lifespan of a single pine beetle is about one year.
Temperatures down to −30 °C to −40 °C (−22 °F to −40 °F) for at least several days, or at least twelve hours of −40 or lower, kills most mountain pine beetles.
Current outbreak
The current outbreak of mountain pine beetles is ten times larger than previous outbreaks.
The recently mild winters have
Alberta forestry officials worried because the beetles will have a devastating impact on an ecosystem which may be ill-equipped naturally to deal with it. Fortunately, a
cold snap in early 2008 is hoped to have dropped the pine beetle population to more manageable levels.
Effect on carbon cycle
Researchers from the
Canadian Forest Service have studied the relationship between the
carbon cycle and forest fires, logging and tree deaths. They concluded that by 2020 the pine beetle outbreak will have released 270 megatonnes of
carbon dioxide into the atmosphere.
Further Information
Get more info on 'Mountain Pine Beetle'.
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