This forest burning contributes about one third of all carbon dioxide emissions causing global warming processes. It is estimated that these slash-and-burners account for at least 60% of all tropical deforestation. It is believed that their numbers continue to rise rapidly with the possibility that their number will reach one billion within two decades.
In 1993, the best estimates are that this could have increased to 500 million. In 1970 it was estimated that the number of small-scale farmers living within or on the fringes of tropical forests numbered at least 200 million. The fate of the former is more complicated and little understood. Eventually part of the latter will enter the drainage system and be lost. Burning also releases nutrients, especially nitrogen, into the atmosphere and into the soil water. The net effect of smoke pollution at ground surface may be cooling or warming depending on the direction of changes of the surface albedo and on the absorption coefficient of the particles in the atmosphere. Extensive savanna fires during the dry season lead to heavy dust concentrations in the atmosphere which may even spread into the region of the perhumid equatorial forest. Small particles remain for periods which may be as long as several weeks or even years in the upper troposphere. Large aerosol particles from burning vegetation spend a short time in the atmosphere but may effectively increase the infra-red re-radiation from the lower atmosphere. Burning is a simple and effective method of land clearing but it has serious consequences for the ecosystem which is being burnt and for its surroundings.īurning emits large amounts of matter into the atmosphere. The objectives of burning are site clearing for shifting cultivation, bush and weed control, hunting, grazing, and often simply for fun. Fire is used extensively in the tropics for the destruction of forests.
0 kommentar(er)
