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What are the common causes of forest fires? Analysis of the causes of forest fire

The forest fire in Liangshan, Sichuan Province, has attracted the attention of many Chinese netizens. It is sad that 30 young and fresh lives have left us. Many people, after learning from the bitter experience, want to know what causes such a fire?

How are forest fires caused? What are the causes of forest fires

forest fire

Forest fire refers to the behavior of forest fire which is out of human control, spreads and expands freely in forest land, and brings certain harm and loss to forest, forest ecosystem and human beings. Forest fire is a kind of sudden, destructive and difficult natural disaster.

The necessary conditions for forest fire occurrence are as follows:

1. Fuel (including trees, grasses and shrubs) is the material basis of forest fire;

All organic matter in the forest, such as trees, shrubs, grasses, mosses, lichens, litter, humus and peat, is combustible. Among them, flaming combustibles, also known as open fire, can volatilize combustible gases to produce flames, accounting for 85-90% of the total amount of forest combustibles. It is characterized by fast spreading speed, large burning area and only 2-8% of the total heat consumed. Flameless combustion fuel, also known as dark fire, can not decompose enough combustible gas, no flame, such as peat, rotten wood, etc., accounting for 6-10% of the total amount of forest fuel. It is characterized by slow spreading speed, long duration and high consumption of heat. For example, peat can consume 50% of its total heat, and it can continue to burn in wet conditions.

2. Fire weather is an important condition for fire;

3. Fire source is the main factor of forest fire.

The ignition temperature of the same forest fuel is different. The burning point of dry weeds is 150-200 ℃ and that of wood is 250-300 ℃. In order to reach this temperature, an external fire source is needed. According to the nature of fire sources can be divided into: ① natural fire sources. There are lightning fires, volcanic eruptions and meteorite landing fires, among which the most common are lightning fires. The most common are in Daxinganling of Heilongjiang, huleng of Inner Mongolia and Altay of Xinjiang. ② Man made fire. The vast majority of forest fires are caused by careless use of fire, accounting for more than 95% of the total fire sources. Man made fire sources can also be divided into productive fire sources (such as burning land, burning wasteland, burning charcoal, spraying fire by locomotive, breaking mountains and rocks, grazing, hunting and burning fire prevention wires, etc.) and non productive fire sources (such as cooking in the field, heating, using fire to drive mosquitoes and animals, smoking, children playing with fire and bad people setting fire, etc.).

What season is prone to fire?

When does the forest fire happen

Forest fire is easy to happen in dry seasons of winter, spring and autumn. The forest fire prevention period (including martial law period) is defined according to local natural conditions and fire occurrence rules.

Therefore, in order to remind people to use fire cautiously in the field, it is necessary to specify a period of time with high frequency of fire in the field as the fire prevention period. In fact, it's not difficult to understand when we think about it carefully. For the vast majority of forest fires, it's mostly human factors. As for the fires caused by lightning strike, ground fire and other natural factors, it's very difficult to encounter this problem What happened. Therefore, the period of forest fire prevention is generally stipulated in the period of maximum use of fire in the field, during which the use of fire in the field is strictly controlled.

First of all, in summer, the plant is in the growth period, with high water content and not easy to burn. There are two reasons why forest fire is not easy to happen in summer. The first is that forest branches are tender and leaves are luxuriant, water is more, and rain is more. The dead branches and rotten leaves under the forest also contain a lot of water, and they will not burn if they are not deliberately arson. The second is that there are less outdoor fires in summer, and there are few farming fires or other fire behaviors except some outdoor picnics. So this period is the non forest fire prevention period.

The second is the frequent use of fire in spring. Spring is the season of spring ploughing, and the use of fire for farming is more frequent. Now, in some forest areas, because of the intertwining of woodland and farmland, many people will uproot some weeds and pile them up together as soil fertilizer when they go to the farmland for land preparation. In spring, because of the strong wind, when burning weeds and ash, the wind is very easy to blow some flames into the dry forest. If you don't pay attention, it will lead to fire. It may be that many young people now go out to work and are engaged in agricultural production at home by some elderly people. In the case of limited labor force, they neglect to take care of the farmland, which leads to weeds. Many people do not eradicate weeds when they tidy up the farmland, but burn them by a fire. In this way, they are more likely to have forest fires in the case of wind assisted fire.

The third is the frequent use of fire for ancestor worship. Spring Festival and Qingming Festival are both in winter and spring and summer. During these two festivals, many places have the tradition of offering sacrifices to ancestors, setting off fireworks and burning incense paper candles. In some places, there are many tombs in the forest area. Burning incense paper candles in offering sacrifices to ancestors is easy to cause fire. For the more cautious people, they may burn up these things, and a very small number of people will light the candle and leave. It is because of this very small number of people that the loss caused by the fire is hard to estimate. Therefore, in order to prevent forest fires, don't burn incense and paper during ancestor worship. Flowers can also express one's grief.

Finally, autumn is the harvest season, some agricultural wastes are more, and the situation of burning crop wastes is more. For example, when planting corn in some forest areas, some people will burn the corn stalk after they take the corn home. At this time, it is also in the period of strong wind and strong grass, which is also easy to cause forest fires.