Forest Fires

Seeing the trail of devastation and destruction in Victoria, Australia this week (February 2009) it is hard to imagine that anything good can come of a forest fire. Wild fires like this are relatively common in many of the warmer, forested parts of the world: the Australian bush, as we have seen, the United States, Indonesia and parts of southern Europe are frequently affected.

Forest fires usually occur in the summer, autumn or during periods of drought, when the wood and foliage of the trees, as well as the low shrubs and ground cover of the under-storey, have been dried out by the heat. It only takes a spark from a bonfire, a discarded cigarette or even a bolt of lightening to set light to this dry tinder, and in these conditions fire spreads rapidly, leaping from tree to tree, and destroying everything in its path. In the Australian fires things were made worse by the high oil content of the eucalyptus trees. Wind is a major factor in the direction and spread of fires, thousands of acres of forest can be burnt to the ground, as sparks and burning leaves are blown ahead to start new fires. The human cost is evident when we look at what happens as these ferocious fires sweep through inhabited areas, and the destruction of the habitat and the species that are lost seem to imply that forest fires have only a negative effect.

There is a more positive side to all this, however, but you have to be able to see the bigger picture. Fires are a natural part of the development of forest ecosystems, and the plants and wildlife that thrive there do so partly because of the fires. The deadwood and debris that litter the forest floor are cleared away by fire, as are some of the large mature trees, allowing sunlight to reach the ground once more, feeding the soil with the nutrient-rich ash, and making room for the growth of new saplings. Some species do not regenerate unless there is a fire, the giant sequoia in the western United States, is a good example. At one time firefighters routinely put out the fires in the forests where these majestic trees grew, but it was soon realised that no new trees were growing, because these trees rely on the heat of fires to open up their fir cones to release the seeds. Now controlled fires are allowed under managed conditions and the trees are thriving once more.

In the past, when the land was less cultivated, naturally occurring fires would have happened more frequently, clearing the accumulation of debris more often, and would therefore have been less severe. Early farmers made use of these fires to clear land for agriculture, utilising the rich soil that was left behind. Today population growth, land use, deforestation and intensive farming are all having an impact on the environment and natural cycles, and it is inevitable that the conflicting agendas of man and nature will clash now and again.