Large, devastating forest fires are now occurring in many regions of the world. In Australia, “controlled” fires are regularly set to prevent uncontrollable fire rollers in the summer months. The US states rely on high-tech fire fighting and firefighters. There are worries about the many coniferous forests, whose resinous needles give off excellent fuel after a long dry period. In apparently less endangered regions of Germany, the forest is observed primarily in order to be able to counter emerging forest fires.
Small cause, big effect
A lightning bolt, a campfire, a carelessly thrown away cigarette or deliberate arson: there are many causes of forest fires. Only in a few cases are they actually triggered by natural forces such as a lightning strike.
For example, after a large fire in the forest of the US state of Colorado in June 2002, a forest department employee confessed to having burned a letter from her husband out of anger at a remote campsite. In March 2003, she was sentenced to twelve years in prison for this.
An arsonist was also responsible for a raging forest fire in the US state of Arizona: a firefighter who had become unemployed had set fire to it to get his job back.
No matter why – if the forest burns once, the fire can spread rapidly to grass, bushes, undergrowth and trees in extreme drought due to heat transfer. Water alone, used with sprayers and fire-fighting planes, is not enough to fight a major forest fire.
Fire-fighting teams cut wide aisles in the forest or set controlled counterfire to prevent the fire from jumping over and spreading or at least to divert the fire so that people and buildings are protected. Flame retardant chemicals are also used.
Controlled fire management
For thousands of years, the native people of Australia, the Aborigines, used to set fires in the forest in spring when the ground was still damp from winter. These “cleansing” fires burned the tall grass of summer and the layers of shed tree bark, but not the still damp trees.
On the one hand, the Aborigines gained valuable fertilizer and at the same time prevented catastrophic forest fires because they had already removed the combustible material on the ground.
The Aborigines did what became known as “fire management” in the 1970s. Until then, forest fires were generally considered harmful, and the Americans in particular did everything they can to put out all fires – even small ones – in fire-prone areas as quickly as possible. But with every success, the risk of fire increased because year after year more and more dry wood and leaves accumulated in the forests.
The point of controlled fires became apparent in 1994 with large bushfires in Australia: The government of New South Wales, where the fires broke out, had banned the deliberate burning of bushes and undergrowth. This enabled the flames to spread rapidly to the gates of the metropolis of Sydney.
Man is to blame
The fact that more fires tend to break out today and cause greater damage is largely to blame for the people. Large cities in California or Australia, but also holiday homes in the Mediterranean region, are expanding into forest and scrublands that are at risk of fire.
The idyllic living in the middle of the lonely nature brings power lines, electrical appliances and possibly careless people into the wilderness as potential causes of fire. In California in particular, more and more people are settling in areas at risk of forest fires, putting themselves at risk.
On the other hand, the rural exodus of people from remote areas is also an important factor in the development of vegetation fires. In some areas of Russia, so many people have emigrated that agriculture is no longer practiced and forests are no longer being managed.
As a result, the regions are increasingly overgrown and more and more dead biomass collects on the ground, which – once dried out – quickly becomes excellent fuel.
And last but not least, people are fueling climate change by slash and burn in rainforest areas. Higher temperatures around the globe allow regions to wither more quickly and more extensively, thereby increasing the risk of fire.
Be it the bush fire in Australia in 1994 or the devastating fire in the American Yellowstone National Park in 1988 – foresters always complained that it would take decades for nature to recover. And they were always taught otherwise by nature. Just five months after the fires in Australia, plant shoots were sprouting from the charred remains of the famous “Royal National Park”.
The adaptation of the vegetation to the fire continues to surprise even experts. With many representatives of the genus Banksie, an Australian steppe plant, the cone-like fruits only fall out after a fire to germinate in the extremely fertile ash.
Fireweed, a North American fireweed, also needs the heat so that its seeds can germinate at all. After a fire, shoots shoot out of charred eucalyptus trees under the protective bark. Because of its thick, protective bark, the North American Douglas fir survives many fires unscathed.
Because more light reaches the forest floor after a fire, many plants such as the Australian acacia take advantage of the opportunity to prevail against otherwise dense treetops. There are also animals that literally “fly” to forest fires: For the family of the “Pyrochroidae”, also called fire beetles, fires are the only chance of reproduction. The beetle’s larvae only develop in freshly burned wood.
Forest fires are therefore, on the one hand, dangerous catastrophes, but at the same time enable ecological renovation. The natural selection during fires creates new living space in partly overaged or diseased trees. The forest fire in Yellowstone Park, where pine trees had formed dense monocultures, also proved to be a successful rejuvenation cure for the forest in retrospect.
Whole animal and plant species are also threatened by forest fires. For example, fires in Australia could lead to the extinction of the koala in the long term. According to estimates by the “Australian Koala Foundation” from 2007, fewer than 100,000 animals live in the wild. With every fire, not only do numerous koalas die – above all the eucalyptus trees, which are essential for the animals’ survival, are destroyed.