PINCHER CREEK, Alta. – The next wildfire to engulf the Okanagan Valley could be far worse than the devastation experienced in 2003 when thousands of acres of trees and 200 Kelowna homes were destroyed.
“The next fire to head toward Kelowna is going to be moving a lot faster and it will be a lot bigger than the last one,” says Bob Gray, a British Columbia fire ecologist.
He studies forest and grassland fires in the northwestern United States, British Columbia and Alberta and is a strong proponent of prescribed fires.He believes that years of litter, dead trees and other fuel need to be removed from the forest floor before a wildfire does serious damage.
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In an interview following a presentation to a meeting of the intermountain division of the Society for Range Management in Pincher Creek, he said the next fire is apt to damage the city of Kelowna even further because of poor municipal planning and a decision not to remove overgrown grass and dead trees.
Many new homes were rebuilt in the same areas with shake shingles, he added, and developments on a mountain surrounded by dry valleys are time bombs.
The loss of natural fires has created problems throughout the western side of the continent. Modern fires tend to burn hotter and produce more smoke because of litter that has accumulated over decades.
There are also changes to forest ecology when fires are suppressed, he told the meeting. Grasslands are lost because a lack of fire encourages tree encroachment. As well, too many trees shade the ground so there is little growth under the forest canopy.
An example is the Williams Lake area in central B.C. Formerly home to Douglas fir, Ponderosa pine, bunch grass and fescue, it is now dominated by Douglas fir, moss and litter.
Fire tolerant species have been replaced and new troublesome species have moved in, choking out natural plants.
“In our dry forest types we are seeing significant changes in fuel,” Gray said. “This is the real consequence because this is what causes all the damage.”
Areas like this have plenty of soil-stored seeds but if fires burn too hot, those seeds are lost.
“Even highly adaptive plant parts that are typically insulated below the soil are just nuked,” he added.
New species such as common juniper move in and cover the ground. Their dry needles accumulate and burn hot, sterilizing the spot. No plants return to these areas, leaving them subject to erosion.
Sagebrush also moves into areas that do not burn frequently.
“In the absence of fire, sagebrush is basically spread all throughout the grasslands,” Gray said.
Soil nutrients can also be lost in fires. Nitrogen disappears if temperatures reach 175 C and organic phosphorus is lost at 350 C.
“The hotter you burn it and the less productive the soils, the harder it is to recover.”
Gray supports controlled burns that can be beneficial when managed properly, especially for grassland restoration.
Ranchers who perform a prescribed burn on rangeland need to be prepared to do without the pasture for three years.
Fire is one way to control encroaching trees but machinery might be needed to knock them down if fire isn’t enough.
Some areas need progressive fires to gradually remove a 100 year buildup of dead fall, plants and needles on the ground. This could take several years of incremental burning, Gray said.
Historically, fires in the Porcupine Hills of southwestern Alberta occurred about every eight years. The Cranbrook area experienced fire every 10 years, Cariboo interior fires occurred every 21 years and Lillooet fires were every six years.
