Friday, April 20, 2007

Guest blog: Wildfires in the Kootenay National Park (Canada)

In support of Project Canada this blog will now from time to time feature small articles written by Arthur Sevestre about environmental and conservational issues in Canada. This is the first one. If you are interested in the goals of this project, please check out the website.

Kootenay National Park has suffered much under wildfires in the past decade or two, as this picture shows. Many square kilometers of forest have been burned, especially during the extremely hot and dry summer of 2003 and much of that area's 'cover of vegetation' still consists only of blackened dead trunks of burned trees. The ground is still barren, nothing grows there, wildlife finds nothing to eat there and that will remain so for years...

Ironically, forest fires are part of the natural processes in these forests. The species are adapted to them and for some of them regular fires are even vital for their survival. But there are roughly two kinds of fires. Under normal natural circumstances, the first kind only burns the surface and what is above it, leaving the seedbank deeper down in the soil intact. The dying of the trees and other older plants gives the seeds in the ground the space and light that they need to develop. Some seedpods that accumulate on or just underneath the surface actually only open to release their seeds when they are burned. And so, not long after the fire, there will be a whole fresh cover of young plants that will eventually grow out into a forest again. This fresh cover is a very important foodsource for many species that cannot find enough food in older forests, which typically offer less of the easy to digest and easy to reach young vegetation. These herbivores then serve as food for predators and so the circle of life runs its course. The size of these fires is usually relatively small and only occurs where enough flammable material has accumulated, which is often only in mature forests where old dry leaves, needles and bark pile up. The relatively low temperatures of this fire makes it burn slowly and when it reaches a place with less highly flammable material, like a recent burn with young vegetation, it will simply go out. In this way, only small patches here and there are rejuvenated, which helps to keep the natural system dynamic and diverse.

Unfortunately, management has suppressed these natural forest fires for many years because they were deemed destructive and harmful instead of rejuvenating and necessary (interestingly, many native people knew about the beneficial powers of wildfires long before 'the white man' even arrived in the Americas). This led to two important results and eventually to the second kind of fire. The first result was that there was no more rejuvenating. The whole area kept on developing into mature forest, and the young vegetation typical for recent burns disappeared. This disturbed the circle of life, because animals that needed the fresh greens to survive were going hungry, and their predators awaited the same fate. The second result was that the heaps of dry leaves, bark and moss that under normal circumstances would have ignited a 'rejuvenating' fire, were kept from doing so and thus only grew higher. The suppression of fires went as planned for a certain period, but with more and more flammable material it kept getting harder and harder to keep it from igniting. In the extremely hot and dry summer of 2003 especially, suppression was no longer possible and many areas of British Columbia and some in Alberta finally caught fire. But this fire had a completely different result compared to the first one. The abundance of food for the flames made them much hotter and they did not only burn the surface, but also the seedbank. Moreover, the uniformity of the forests meant that the fires found food everywhere and were not stopped by areas with less flammable material. Therefore, much larger areas burned in one time. These fires were not rejuvenating, they were sterelizing! And instead of bringing diversity and dynamics, diversity took a deep dive and the area will not be dynamic anymore for a long time. It will take many years for seeds to arrive in the area again and for nature to restore itself again.

Since the last decade of the 20th century, realisation is growing that wildfires will have to keep occuring. Fortunately, management is adapting to that knowledge and now sometimes intentionally sets fire to certain areas before there will be enough food for the flames to make them too hot. The fires are still more or less controlled in that way, so that human activities in the area are less affected by unpredicted fires. It is a step in the right direction, but much research is still needed to find the best ways to manage this phenomenon.

written by Arthur Sevestre

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