HYDROLOGIC EFFECTS OF BURNING AND FOREST FIRES:
Wildfires are a regular periodic phenomenon in many parts of the world, esp so in arid regions. In humid temperate climates, such fires have become rare and are usu confined to exceptional drought in summer.
The fires are either accidental caused by lightning, neglecting, or sparks; more often they are intended as a sort of tool in land mgt.
- Rangelands in many regions are regularly burned at the end of the dry season for the purpose of removing the unpalatable old growth and stimulating fresh growth/ feed.
- Forest burning may be practiced as a Silvicultural measure to stimulate regeneration (prescribed burning) or for the purpose of land clearing.
- Protective burning is a preventive means of fire control whereby inflammable dry fuel accumulated on the ground is destroyed at the beginning of the drought season to prevent accidental and catastrophic fires during this season.
TYPES OF WILDFIRES:
- Ground Fires: Small fire starts from the ground and can be controlled.
- Stem Fire: Effect individual trees cause damage to stem but could be controlled.
- Crown Fire: Caused by the spark or jumping over via dry under shrubs. Causes severe damages.
SUSCEPTIBILITY OF TREE SPECIES TO FIRES:
- Eucalyptus are particularly inflammable perhaps because or aromatic oils they evaporate, but most species have a remarkable potential for recovery from fires
- Conifers esp Chir pine is also much endangered to fire due to the presence of resin which is highly inflammable and dry needles; such forests may be completely destroyed as most spp do not sprout.
- Susceptibility is in the following sequences: pine, spruce, fir, larch, and pole crops are endangered to fire.
- Thin bark hardwood like oak, eucalyptus, beech, etc is easily damaged than thick bark.
CONSEQUENCES OF WILDFIRE:
- These may be permanent or temporary. Even temporary effects last many years.
- Affected is always vegetation, but also soil structure, depending on the intensity of burn which in turn influenced by the weather situations.
These are rarely hot, they traverse the land rather quickly and heat does not penetrate much into the soil. Humus is usu conserved, but plant cover and litter can be consumed entirely. Fires of this nature leave behind exposed soil and ash beds. Since root tops of perennial grasses are fairly well protected in the soil. They can sprout vigorously as soon as weather situation is favorable. Seeds in soil do not necessarily loose viability, hard-coated seeds, such as legumes, can even be stimulated by heat while fine seeds on the soil may be destroyed. As a result, the spp composition may be changed.
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