The investigation results of Xichang 33 forest fire were announced. What are the causes of forest fire?

Forest fire is a worldwide problem. Because it often occurs in dense forests, it is difficult to put out the fire. The main causes of fire are natural fire and man-made fire. Natural fire sources mainly include volcanic eruption, meteorite landing, lightning fire, rolling stone sparks, etc. Man-made fire sources include burning reclamation, burning wasteland and burning charcoal. More than 9% of the fires in the world are caused by people.

One of the conditions for forest fires is to have flammable materials, and the litter accumulated on the surface is a good match. The previous Liangshan forest fire was related to surface deposits. After long-term accumulation, ground vegetation and undergrowth combustible materials rot and deteriorate, producing a large number of combustible gases. When the decomposed combustible materials are mixed, they will burn or even deflagrate when they meet an open flame. The occurrence of forest fires is also related to the climate. Under the dry climate conditions where fires often occur, high temperature and low humidity are the best environment, which is generally common in spring and autumn, and also occurs when rain is scarce in summer. Gale weather is also an important condition for mountain fires. Wind can change the thermal convection and provide oxygen for combustion, which makes the wind direction of the ignition point changeable and makes the fire fighting more difficult.

In p>219, the mountain fires in Australia burned for more than half a year, which caused great ecological damage. The forest density in Australia itself is very high, and there are local regulations, and it is not allowed to cut down indiscriminately, even cutting the isolation belt should not be allowed. In addition, the trees at the fire point are all eucalyptus trees with grease, so it is difficult to put out a fire, and it will spread in a concentrated way. In addition to the serious damage to trees, the animals in the forest have almost suffered extinction. For example, koalas are small in size, slow in movement, and used to move to the canopy when they escape, so they will be swallowed up by fire.

It has to be said that Australian residents' ability to respond to fires is indeed a little slow, and the number of firefighters is insufficient, so the fire fighting work is progressing very slowly. Because Australian mountain fires have also brought great influence to the global climate. The smoke from the fire even drifted to South America along the west wind.