Insect Infestation: Another Effect of Climate Change

Image via WikipediaThe Death of North American Forests by Marlene Affeld

Although it is sunny, ominous black clouds lay low on the horizon. The day matches my dark mood. I am grieving. A kind neighbor, Lyle, is on his way to come to cut down and remove seven of the magnificent trees on my land. It is painful to fall trees that I have pruned and nurtured for many years. I have no choice, they are infected with the dreaded Mountain Pine Beetle.

Across the western United States and Canada, our majestic pine forests are being destroyed by a massive infestation of an insect pest, the Mountain Pine Beetle or Bark Beetle. In the largest North American insect infestation in recorded history, millions of acres of evergreens are infected; our forests are dying.

The Mountain Pine Beetle, also known as the Rocky Mountain Pine Beetle, Black Hills Beetle or Bark Beetle (Dendroctonus ponderosa), is a nasty pest that is native to the pine forests of western North America. Infestations of the beetle are rampant in wilderness areas as well as suburban back yards. The beetle is not choosy. Trees that are not healthy due to crowding, drought, old age or have been damaged by wind or lightning are most likely to come under attack. However, as beetle infestations spread, MPB attacks may involve the majority of the large trees in the outbreak area. Lodgepole, ponderosa and scotch pine are most susceptible. Once infected, there is nothing that can be done to save the tree. Although it may take several months for the ugly orange colorization to appear, death is inevitable.

The female beetle kills the host tree by burrowing into the bark to lay its eggs. The invasive adult beetle carries spores of a blue-staining fungus (Ceratocysis minor). As the beetles gnaws its way through the bark, the spores of this fungus are dislodged and slowly begin to germinate. Within a matter of weeks the fungus invades and blocks the conductive vessels of the sapwood and inner bark of the tree. As the vessels are constricted, the verdant foliage starts to fade, first to a pale green, then a straw yellow and then, after about a year's time, the needles will turn red brown.

An unprecedented deadly combination of exceptionally warm winters, reduced snow pack, drought and control of forest fire has allowed the pest to flourish.

In Montana the infestation is catastrophic. Over a million acres of pines have succumbed to the deadly blanket of rust that is creeping across our mountain faces. A million acres of trees is over a billion board feet of timber. In Montana, as in many states, much of our local economy relies upon the timber industry. The loss of significant areas of our forests portends the closure of sawmills, post and pole, chip and lumber yards that provide much need employment. In Montana alone, thousands of loggers, drivers and millwrights are looking for work.

In southern Wyoming and northern Colorado, the situation is even worse. Both of these western states lost over a million acres to the beetle in 2006. In 2007 total acreage infested exceeded a million and a half acres in both Wyoming and Colorado. Projections for 2008 are dismal with the range of the beetle expected to top two million acres per state. Forestry experts predict, that within the next three to five years, over five million acres of the forests in Colorado will be dead. Already, in many areas, all the lodgepole pine has been wiped out as far as the eye can see.

Within the United States, California has suffered the greatest damage. Oregon, Idaho and Washington states are not immune. Massive swathes of forest have succumbed to the Mountain Pine Beetle. The infestation has left over 50 or more dead trees per acre around Camel and Deadhorse Lakes and the Gearhart Mountain Wilderness areas of Oregon. Utah, New Mexico, Arizona, western Texas and south across the border into northern Mexico, all have areas of infection. The death of North America's forests is carried on the wind.

Beetle infestations are commonly found in forests with a mid-elevation of 2,000 to 6,000 feet (600 to 1800 m). However, in Canada beetle populations have been found below 1,000 feet (300 m) and in northern Mexico beetles have been identified above 8,000 feet (2,400m).

The Canadian provinces of British Columbia and Alberta have been impacted the most severely with over 33 million acres destroyed in British Columbia and the blight is moving across Alberta. Centuries-old pines at the highest elevations, once seen as impregnable due to extremely cold temperatures that destroy the beetles, are rapidly dying. The devastation of the ecosystem is going to have long-termed damaging effects on wildlife habitat, watersheds and all wildlife that is dependent on pine forests.

Woodpeckers, parasites and predators play an important role in reducing the population of a developing brood within a tree. Although they may help stabilize a tree with a low level of infestation, their actions alone will not contain an outbreak.

Forests that are damaged by beetles are tinder dry and provide abundant fuel for forest fires. Across America conditions are prime for forest fire to sweep across the land. Considered the worst fire disaster in history, the 1910 Fires that ravaged the northwest had far less dry fuel than exists today.

Although I dread the cold, I am praying for a long, hard winter. Frigid winter temperatures below -20F (-27C) that is sustained and lasts for several days is the only way to kill the brood beetle population.

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Marlene Affeld's passion for the environment and all things natural inspire her to write informative and insightful articles to assist others in living a Green Lifestyle. For more Green Living info visit Nandu Green at http://nandugreen.com.

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