Causes and Types of Forest Fires
Forest fires are a common problem across the world posing significant threats to terrestrial, aquatic and atmospheric systems also. Every year, extreme wild fires lead to loss of forest wealth, biodiversity, ecosystem functioning and landscape stability.
Causes of Forest Fire
Forest fires can be caused by natural as well as manmade causes.
The natural causes mainly include lightening, volcanic eruption, sparks from rock falls, and spontaneous combustion. Each of them is a source of ignition which sets on fire in forests. Favourable circumstances for spread of forest fire are provided by high temperature, low humidity, abundance of combustible material etc.
As for manmade causes, forest fire can break out when a source of fire such as a flame, cigarette, electric spark or any other source of iginition comes in contact with some inflammable material in forests due to human neglect or intention.
Since forest fires can be caused by both natural and human causes, they are treated as ‘quasi-natural’ hazards. This means that they are not entirely natural hazards akin to volcanoes, earthquakes and tropical storms.
Types of Forest Fire
Forest Fires can be broadly divided into two categories viz. Surface Fire and Crown Fire. A surface fire begins at surface and spreads along the ground with surface litter (dry leaves, twigs and grasses) on the forest floor. In Crown fire, the crown of shrubs and trees burn. The crown fire is generally sustained by the surface fire. We note here that crown fire in coniferous forests is most dangerous because of the resinous material given off vigorously by the burning trees. However, it also helps the ecosystem there because once the canopy is burnt away; sun light is able to reach to the ground supporting life in the aftermath of fire. In Savannahs, the forest fire is usually surface fire and results in longer term damage because it kills or suppresses the seedlings and prevents further growth.
Forest Fires in Different Regions
Forest fires are common phenomena in the forests rich in grasses, woods, bushes, scrubs or peat. The reasons and implications of forest fires vary from region to region. For instance, in Canada and North West China boreal forests, lightening is major cause of forest fires. In other parts, forest fires are generally man made. Further, human neglect is also one of the major reasons of forest fires in China, US etc.
Forest fires in Taiga
Forest fires are important feature of the Taiga biome and it is generally caused by lightening. Due to frequent forest fires, the Taiga plant communities have special ecological features to make them more resistant / adapted to fire. For example, the older trees of Taiga biome have thicker bark. In some plants such as Jack Pine, the seed cones open up immediately after a wild fire and these seeds work as pioneers of development of new trees.
Forest Fires in Savannahs
Akin to Taiga, forest fires are common in Savannahs also. However, most forest fires in Savannah are caused by human interference or neglect. One more difference between fires in Taiga and Savannah is that, while Crown fires are common in Taiga, Surface fire is common in Savannah.
Topics: World Geography