A forest fire is an uncontrolled fire occurring in nature. it is a large, destructive fire that spreads over a forest or area of woodland consuming all the natural fuel of the forest. Sometimes, it is so massive that it takes a long time for the fire-fighting crews to gain control over the situation leading to massive destruction.
Forest fires take place all over the world. Major fires happen every few years in the forests of the United States, Indonesia, Australia, India also in Nepal( in 75 districts out of 77 in 2021). Forest fires happen mainly in the summer and autumn.
Types of Fires Based on The Place of Action
Ground fire burns the herbaceous growth on the forest floor together with the layer of organic matter in various stages of decay, which covers the soil. Consequently, it burns very slowly but persistently with instant heat and rather uniform destructiveness. Such a fire may burn over several acres in a day. There may or may not be much smoke, but there are practically no flames consequently it becomes difficult to find the area affected and to take control sooner.
Surface fires are those which burn on or near the ground in the litter, ground cover, underbrush, and reproduction. They are the commonest kind of fire and occur in all parts of the country.
It is fire which not merely burns the ground cover but also the under growth and middle storey of the forest.It causes considerable damage to the forest by destroying the young generation,wildlife and even the pole crop of the favoured species.
Plain fire is mostly surface fire and it is so located as to be strongly affected by surface winds and there is a plentiful supply of oxygen for purpose of combustion. It is the main trouble in Nepal.
Hence surface fires are characterized by relatively rapid spread, an abundance of flame, and heat, but soon die out.
It is a forest fire that spreads through the crowns of the trees and consumes all or part of the upper branches and foliage. It is the most devastating type of fire. This type of fire causes immense loss of life and property. The foliage at least is consumed and the tree usually is killed through overheating of the cambium. It is the major issue of the foreign countries having coniferous forests. It’s hard to take control over crown fire.
Causes of Forest Fire
After deforestation “forest Fire” is the major reason for forest destruction. A single uncontrolled fire can ruin extensive areas.
- Lightening, alone causes around 30 % of the forest fires in western countries.
- Rolling of stones.
- Rubbing of bamboos/trees with each other.
- Volcanic eruptions lead to forest fires.
- Increasing drought period(climate change).
Man-made (Anthropogenic) causes:
- Throwing of a burning match stick, Bidi, or Cigarette stumps in the forest by grazers or other travelers.
- Throwing of fire carelessly after illicit collection of honey.
- Burning of grasslands in the villages carelessly which spread to the forest area.
- Accidental spread of fires while burning fire lines departmentally
- Leaving the fire used by travelers for picnics, tours etc
- To destroy the stumps of illicitly cut trees in the forest areas.
- Carelessly burning fields for increasing the production of agricultural products.
Effects of Forest Fire
An average of 19.8 million ha of forest are reported to be significantly affected annually by forest fire according to FAO. Their area almost every sector which get affected directly or indirectly due to uncontrolled forest fire some are listed below:
- Damage to tree
- The damage may range from small scar to complete combustion of the tree.
- Fires occurring early in the growing season are likely to kill a large percentage of the trees in a stand.
- Death of tree caused by overheating of cambium.
- Trees with shallow root systems suffer more than the deep-rooted species because roots are not covered by a protective layer as bark in the upper portion.
- The broad-leaved trees are less affected by forest fires than the conifers.
- Damage to regeneration:
- Fire damages the regeneration completely as most of the regeneration is completely wiped out in ordinary ground or surface fire
- Repeated fires may kill the small seedlings and then the regeneration may be lost completely.
- Increases the chance of insects and pathogens entering through scars created after the fire, makes trees, and poles more vulnerable to disease, and reduces their economic value to it.
- Damage to soil:
- Affects soil physically, more than chemical, by changing the amount and condition of organic content in the soil.
- Increases the chance of soil erosion by exposing it to direct sunlight when trees, litter, and saplings are burnt away.
- Destruction of soil organic matter affects the soil structure adversely. Nitrogen reserves of the soil are depleted.
- Affects soil microflora and fauna which in turn affects the forest growth
- Fire makes soil compact and impervious affecting its regeneration.
- It invites undesirable, invasive species and creates unfavorable environmental conditions for the target species.