Monday, 16 November 2009

Forest Fire Suppression

Traditionally during the twentieth century, forest fires have been viewed primarily as a negative which humans should always attempt to suppress as fully as possible where the capability exists. That is the strategy we have followed, and unfortunately, in many cases, this has caused more harm than good. Forest fires are a natural occurrence that species and ecosystems have evolved to deal with over millennia. In recent years, scientists and fire fighters have begun to reconsider this approach.

Historically, there has been a wide variety in forest conditions in large regions of boreal and temperate deciduous forest, as found in the western and northern US, Canada and Russia. Over thousands of years, forest fires have happened regularly, in different areas, at different intensities, and at different times. This means that at any given time there are recently burned areas, alongside young forest and old growth forest areas, and everything in between.

In areas of a recent burn, while the trees may be dead, their remains and the lack of shade, provide a very hospitable environment for a different variety of species. Only the outside of the trees, the bark, is burned, inside is fresh wood. Many types of beetles will come from as far as hundreds of kilometres away to eat the unprotected wood and lay their larvae. Birds especially adapted to eat this larvae will also seek out recently burned areas in order to burrow into the dead trees and eat the grubs.

Many plant seeds remain dormant in the ground for years, or even decades, and begin to sprout after a forest fire, taking advantage of the access to sunlight and the rich soil left behind from the fire. Smaller trees that require more sunlight, and are resistant to the beetles, such as spruce or fir, will begin to grow in place of the original trees, such as pines. Eventually the pines will regrow as well, but it will take a long time before they are large and tall enough to dominate, creating an intermediate ecosystem.

This is a natural lifecycle of growth, death and re-growth that creates a patchwork throughout a forest region. This provides several advantages. First, areas of different ages can support dramatically different ecosystems, and are home to different numbers and types of plants, animals and insects. This allows for a large amount of biological diversity. As this patchwork evolves, different species will migrate to different areas, and different plants will sprout or die, in a continual cycle.

Another great advantage to this diversity in forest growth is that it provides natural firebreaks. Any new forest fire is naturally contained by other areas that have recently burned, which it cannot cross. Contrast this to many forests today. In many cases active firefighting over decades or longer has created vast areas of homogeneity. When a fire breaks out in an area like this, it may spread much further and cause much more damage than was historically possible. This is similar to the creation of monocrops in agriculture where vast areas are at risk from a single disease or pest.

Also, because of extensive forest fire suppression, there are fewer habitats for the plants and animals that thrive in recently burned forest areas, or in areas of young forest growth. Without a sufficient number of these areas for animals to migrate to, or for plants to grow in, many species are seeing large reductions in number and may be subject to extinction down the road.

Fortunately many scientists and fire fighters are now pushing for changes in forest fire management. This is important not just for protecting the environment, but also for saving lives and reducing costs. The costs of firefighting have rising dramatically as humans have expanded housing to areas that are greatly at risk of fires. A large percentage of the expense often comes from protecting a small number of homes. This often leads to a higher loss of life by firefighters as well.

Today firefighters are often taking a different approach. They will sometimes allow fires to burn in areas that are unpopulated, though they will still try to limit the size of the area. This will hopefully lead to a greater variety in ecosystems in the future, which could reduce the costs and risk of firefighting. Also, the goal is no longer to protect all homes. A risk and cost assessment is now often done, and in some cases where the risk or cost is too high, people will be evacuated, and the homes allowed to burn. Hopefully this will lead to a realization by local governments that some areas are just too risky to allow for the construction of large expensive houses, and the infrastructure needed to support them.

The lesson here is that forest fires are a natural event that have been part of the ecosystem for thousands, or even millions of years. Not only has life adapted to this, in many cases life depends on a regular cycle of burning and regrowth. We must protect areas where there is a high population density, but in other cases, it makes more sense to allow nature to take its course. In the long term, this will help to naturally limit forest fires, save money and lives, and contribute to a healthier environment with greater biodiversity.

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