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Thursday, October 15, 2009

Climate Change and the Mountain Pine Beetle in Northern British Columbia

Posted by Melanie at 12:22 0 comments

written for the blog action day on climate change

Every year I mentally resist the signs of winter. As the skin baring days of summer get shorter, tree leaves turn yellow and fall off, mornings are white with frost I struggle to come to terms with reality. But, like an early snowfall which melts and snows again, finally sticking around for the duration my mind and body eventually resign themselves for the long haul.

I live in Northern BC. Winter is a full seven months long. Before it is half over I’m fed up. I’ve lived up here for half my life. At first I found the intense cold and the bottomless layer of snow that settled in and stayed till spring unfathomable.

One year, winter arrived and melted in two months. I remember standing outside on Christmas day in a tee shirt, unheard off.

Winter may go on for months but the temperature moves around, from minus forty, or lower, back up to zero and back down again. Spring comes when the days of zero and above zero temperatures become more frequent and stay there. Really low temperatures make getting around difficult. The extreme cold air hits ones nostrils instantly turning to ice and as Environment Canada keeps reminding us- exposed skin can freeze in a ridiculously shot time. We compensate by covering our bodies in layers and layers of wool and down, for the short dash from house to the car.

Scientists have been telling us for two decades that the number of extremely cold days have been getting fewer and fewer. At first glance this may seem like a good thing especially for us fragile humans but it also turns out that warmer winter days are a good thing for the insect population.

during a normal winter a few weeks of extremely cold weather, minus thirty degrees celsius or lower, is enough to kill the Mountain pine beetle, (MPB), Dendroctonus ponderosae, and its larvae but this has not been happening for nearly two decades allowing the pine beetle population to increase to epidemic proportions.

Female beetles bore into a mature pine tree (one that is at least eighty years old) secreting a pheromone that attracts male beetles. The tree responds by secreting a toxic resin in an attempt to kill the beetles however, each beetle carries spores of a blue fungus in its mouth. As they tunnel their way under the bark of the tree they release these spores. As the fungus spreads through the tree it stops the spread of the toxic resin. The beetles lay eggs and the larvae from these eggs feed on the fungus as they develop and in turn carry the fungus spores onto the next tree when the present one is dead.

As well British Columbia’s forest management practises, to limit forest fires, have increased the stands of mature lodgepole pine making it easy for the beetle to eat its way across the northern part of the province.

Usually, without the influence of humans, the mature trees become crowded with other trees and the forest becomes susceptible to fire. As the trees burn the pinecones drop to the forest floor releasing their seeds, which need heat to germinate. A new forest grows up and the cycle continues.

The beetle infestation is devastating for BC’s forest industry. Beetle wood has a characteristic blue stain due to the fungus present inside it. Harvesting this dead wood has to be done quickly, within five to eighteen years before the trees lose their commercial value. Back in 2006 my husband and I built our log house out of beetle killed pine.

A beetle killed pine tree is a characteristic orange easy to spot from a helicopter or when driving down the highway.

The other devastating problem for all this dead pine is the massive forest fire potential. The city of Prince George, where I live, has cut down most of the dead pine within the city and immediate surrounding area.

Private homeowners have been encouraged to do the same. The dead pine is reused as firewood or sold to lumber mills.

Today the only surviving pine trees are those too young for the beetle to bother with. The lack of food has forced the beetle to move on, find another source of food or die. The dead pine trees still left and there are hectares and hectares of them have mostly lost their orange colour because their needles have dropped off. This wood is good for nothing except a giant forest fire.

Photo by D. Huber

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