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Federal Research Center 
"Krasnoyarsk Science Center of the Siberian
Branch of the Russian Academy of Sciences"

 Федеральный исследовательский центр «Красноярский научный центр Сибирского отделения Российской академии наук»

Federal Research Center 
"Krasnoyarsk Science Center of the Siberian
Branch of the Russian Academy of Sciences"

How do forest fires affect the environment?

11 July 2019 г.

Как лесные пожары влияют на окружающую среду?
The number of forest fires in Russia is increasing fr om year to year. The damage they cause is difficult to assess. While the price of the dead forest stand, and harvested timber burnt can be calculated, it is almost impossible to estimate the loss of the environmental functions of damaged ecosystems.
Peter Tsvetkov, Doctor of Biological Sciences, Head of the Laboratory of Forest Pyrology of the V.N. Sukachev Institute of Forest  KSC SB RAS, told the RUSBASE publishing house about the main environmental consequences of fires, how fires are extinguished and how long it takes to restore forests.

Damage fr om fires is not only the economy

Forest fires have a huge impact on forest ecosystems across the globe. Almost a third of forest areas per year is caught by fire. Trees die, grass burns out, bushes, mosses and lichens, as well as soil are damaged, including dead microorganisms.
One of the main negative environmental consequences of fires is smoke and air pollution. Animals and people often die not fr om fire, but from smoke poisoning. Smoke from large fires can spread hundreds of kilometers. Smoke in the lower atmosphere negatively affects the people’s health, especially it concerns children, the elderly, pregnant women, and those with cardiovascular diseases.

Strong smoke after fires delays the development of plants, so they emit less oxygen, while the forest is its main supplier. Recently Krasnoyarsk scientists, together with colleagues from the German Max Planck Institute for Chemistry, estimated the emissions of greenhouse gases into the atmosphere during forest fires in Siberia. During intensive burning of the forest, the concentration of carbon monoxide in comparison with the background content in the air increases almost 30 times, that of methane - twice, and that of carbon dioxide - by 8%.

Emissions from fires increase the greenhouse effect, which consists in the fact that the sun rays reflected from the earth are transformed into long-wave thermal radiation, which is absorbed by greenhouse gases. As a result, the air temperature rises. According to the calculations of the Krasnoyarsk scientists, during the combustion of a kilogram of dry matter in the Siberian taiga, slightly more than a kilogram and a half of carbon dioxide, a little more than a hundred grams of carbon monoxide and four grams of methane are emitted into the atmosphere.

Substantial  consequences

Fires can cause changes in the species biodiversity, replacing some organisms with others. According to the estimates by the Krasnoyarsk scientists, about a third of the fires in Russia leads to the change in the type of vegetation. For example, it is well known that, under certain conditions, in the burnt areas instead of the dead coniferous forest there appears aspen. Economically, this tree species is less valuable.

Fires can cause changes in the zoological and microbial world. Having changed after the fire the environment becomes unsuitable for animals that lived there before. Therefore, they have to move to other more suitable conditions while other organisms take their place, for which the environment formed in the burnt areas is more consistent with their requirements. An example of this is cedar forest inhabited by squirrels. After a fire, as the cedar forest dies, the food supply of the animals disappears, and they have to move to other parts of the forest.

Fires can affect the bogging of forest soils and increase the risk of flooding. They can lead to soil erosion, contribute to the formation of landslides and solifluction - slipping of the soil thawed on the slope along the frozen bottom layer together with the vegetation cover. This process is especially characteristic of the northern territories and permafrost zones. The consequences of forest fires are often outbreaks of insect pests and forest diseases, which primarily involve trees weakened by fire.

Another issue to which forest fires contribute is acid rain. During combustion, smoke, soot, and other harmful compounds are formed. Interacting with the air moisture, they form acid precipitation, which adversely affects the soil, plants, and water bodies. For example, in water with a broken acid-alkaline balance, many species of mollusks and other organisms making shells from calcium cannot have their own “houses” - they simply “dissolve”.

Restoration of the lost

After a fire, reforestation may take different time. In the north, this process takes much longer than in the south. The renewal of the living soil cover consisting of grass, shrubs and mosses, proceeds rather quickly and can begin as early as the next year after the fire. For lichens, this process is slower and on average takes up to 60 years. For moss cover, it takes about 30-40 years, depending on the natural conditions.

Restoration of coniferous forests after a fire in the case of the species change proceeds much longer than in the case of their direct renewal. Coniferous trees live long, deciduous ones are less durable, but grow faster.
It is difficult to determine the exact period of forest regeneration, since it depends on particular conditions of growth, strength and types of damage, as well as on the type and form of fire.

Even a weak but prolonged burning can cause significant damage and lead to a long restoration of the forest. Such a factor as the time of year when there occurs a fire affects the restoration as well. The fire could occur in autumn when the foliage has already fallen and the trees are ready for winter and the situation can be much harder in spring when the trees have just “woken up” and are ready to blossom.

What is to be extinguished?

The consequences of fires can be severe, so we must fight fires. But it is difficult to do this, as the forest service lacks funding and experienced staff. Long-term practice shows that a simple increase in financial and material investments in forest protection does not lead to a consistent reduction of fire hazards. Fire has its own ecological role in the forest, it cannot be completely excluded. To solve the problem of fires, it is necessary to create a system to manage them.

In the new economic situation with the lack of funding and a wide variety of natural and economic conditions, it is necessary to pass from the concept of fire fighting, which implies imperative fight against all fires, to the concept of fire management at the level of the entire country. It is based on the principles of prioritized selection of fire extinguishing and suggests the differentiation of forest protection levels. The V.N. Sukachev Institute of Forest KSC SB RAS has developed a system for predicting the behavior of fires, which is the basis for the concept of fire management. It includes the information base on the classification of combustible plant materials and methods of their mapping, a model of the speed of fire propagation, and a method for predicting the behavior of natural fires, their intensity and consequences.

Due to the lack of material and financial resources, in 2015 so-called forest fire control zones were introduced by order of the Russian Ministry of Natural Resources. The control zones are areas wh ere  it is allowed by decision of the state authorities of the constituent entities of the Russian Federation not to extinguish active forest fires. It is admitted to cease fighting operations in the absence of a threat to human settlements or economic facilities in cases wh ere the anticipated firefighting costs exceed the predicted damage from the fire. This decision is made by the Commission for Emergency Management and Fire Safety of the executive authority of the RF constituent entity. It primarily concerns the northern territories and does not apply to suburban areas wh ere fires must be extinguished.