Flourishing forests need fires

Attack from the air on a fire in Montana

By environment correspondent Alex Kirby

Forest fires often destroy homes and ravage wildlife.

But the forests will ultimately benefit from the effects of the flames, which are a natural way of clearing old growth.

Some experts even criticise the practice of trying to prevent fires at any cost, saying this means bigger problems when the flames take hold.

And they say policymakers need to accept that they are responsible for the devastation, by stopping smaller fires breaking out in the past.

Fires are often blamed for reducing the fertility of the soil and destroying animals and plants, apart from the damage they do to human interests.

No through road for anyone

But, with one important exception, fire is a natural and vital part of forest life. Although people cause most fires worldwide, the most common natural cause is probably lightning.

The exception is fires in tropical forests, with their high levels of humidity and moisture. They do not normally burn, and can be very badly damaged by fire.

In most other parts of the world, though, the right fire - one that can be controlled - in the right place is a way of letting the forest regenerate itself.

Seeds from fire

Burning causes organic matter to decompose rapidly into mineral components which cause plants to grow fast, and it recycles essential nutrients, especially nitrogen.

Some tree species cannot survive without periodic blazes. Lodgepole and jack pines are serotinous species - their cones open and their seeds germinate only after they have been exposed to fire.

In Australia, the mountain ash, a flowering tree which grows in temperate areas, needs a site to be thoroughly burnt and to be exposed to full sunlight before it can regenerate.

Forests adapt themselves to relatively small intermittent fires. But when policymakers try to suppress fires altogether, they encourage the accumulation of dead growth and allow new species to establish themselves.

Firefighters arrive from afar

When a fire does start, it finds more fuel to sustain itself than would normally be there.

Dr Steve Howard, of WWF's Forests for Life campaign, told BBC News Online: "Many forests have evolved to burn, and fire plays a key role in maintaining a healthy functioning ecosystem.

"This is true of the forests in the 11 US states that are burning now. But people have been interfering there for almost a century, preventing the fires which would have broken out naturally every two to seven years.

"The result is plain - fires 10 times stronger than they would otherwise have been, with 10 times more impact on nature, and 10 times harder to control.

"What we need to do is to get nature back in order by a programme of controlled burning, setting fire to small areas at the start or the end of the growing season.

"These fires are man-made. We've inherited a hundred years of fire suppression."