Clima y alimentos 

Bases

Hoja de ejercicios: Sequía en el Mediterráneo

Hoja 2: Causas de los incendios

El fuego ha sido siempre una parte del ecosistema del bosque, pero en la actualidad la frecuencia de esos incendios aumenta poco a poco.

Cuando las causas de los incendios son naturales, los bosques son capaces de recuperarse después de cada uno y volver a colonizar las zonas dañadas sin problemas. Pero actualmente los incendios son mucho más frecuentes y mucho más intensos, lo que hace imposible que los bosques puedan recuperarse por sí solos. Incluso los bosques tropicales sufren enormes incendios.

Según la organización protectora de la naturaleza WWF (World Wide Forum) y la Organización Mundial de los alimentos y la agricultura FAO (Food and Agriculture Organization) el 95% de los incendios forestales está causado por humanos. 

Cada año más de 50.000 incendios forestales 

WWF pide que se utilicen medidas preventivas para evitar las catástrofes en el Sur de Europa.

Después de los incendios desastrosos de Córcega y la Costa Azul (La costa mediterránea de Francia), se hace obvio el peligro de sufrir grandes pérdidas debidas a los incendios en el área del Mediterráneo.

Incluso ahora, entre 600.000 y 800.000 hectáreas de bosque son arrasadas por las llamas cada año, lo que es equivalente al tamaño de la Isla de Creta.

Más de 50.000 incendios arrasan cada año el 1.5% (como media) de los bosques mediterráneos cada año.

La gran biodiversidad de esta zona disminuye constantemente también como consecuencia de estos incendios provocados por el hombre.

En paises como España, Italia, Portugal o Grecia, el número de incendios se ha multiplicado por cuatro desde los años 60.

Las sequías más largas, la baja humedad y las olas de calor extremas son una mezcla muy peligrosa. Con el aumento de los incendios forestales los ecosistemas mediterráneos son incapaces de regenerarse a la velocidad necesaria.

En muchos lugares puede observarse fácilmente la pérdida de biodiversidad, la escasez de agua, la erosión del suelo y la aparición de zonas desérticas. Aproximadamente unos 300.000 kilómetros cuadrados de costas europeas están en peligro de sufrir estas consecuencias.

La reforestación tampoco es siempre una solución apropiada ya que, muchas veces, seon bosques mucho más tendentes a sufrir incendios que los bosques naturales.

To come up against the increasing danger of fire, strict laws and high penalties must be set up. Many of these 50000 fires of the following year can be prevented, if the governments start to rethink and spend their money for preventive measures instead of only paying for the extinguishing of blazing fires. An improvement of the cooperation of all institutions which are involved in the process of fire extinguishing is a first reasonable step. In many cases big fires could be prevented if the coordination of all had worked better. … (Based on an article by the WWF 2003 – source: http://www.wwf.de/presse/pressearchiv/artikel/01349/index.html)

Exercise:

1. What reasons for forest fires and consequences are mentioned in the text?

2. Aside from the solutions described in the text, all humans can contribute to the protection of forests. Design a danger sign, which points out the danger of forest fires to the visitors and shows the most important behavioural rules (cigarettes, fire…)!

The global view

In Europe the Mediterranean region often makes the haedlines in terms of vegetation fires ... but what importance does Europe have if you see fire events with a global view?

Have a look on the world forest map below. Different type of forests are shown here in different countries. Click also on the thumbnails below, to see different regions in a higher resolution (70 K per image).

The global forest map
from United Nations Environmental Programme - World Conservation Monitoring Centre
http://www.unep-wcmc.org/forest/global_map.htm

Thumbnails:

A

-

B

C

D

Exercise: Fires can be a catastrophy for the Mediterranean region. But of what importance are the Mediterranean fires for the world's climate?
- Compare the numbers in the world map and find out which thumbnail (A, B, C, D) and which of the texts below (a, b, c, d) belongs to which number.
- Read the following texts, compare the areas burned and describe in a few lines what you think, what the relevance of Mediterranean fires for the global climate is and why you think this!

Fires on a global view

a) Every year in many countries of the African continent several million hectars burn, e.g. 7.5 Mio ha in the relatively small country Benin, where vegetation is traditionally burnt in order to transform it into agricultural land, and 60 Mio ha in Sudan with its wide savannahs. Partially such fires are part of a natural cycle (e.g. savannah fires) and the regrewing vegetation takes up again the carbon dioxide emitted from the fires, partially there is a long term damage basically due to human activity and transformation into agricultural lands.

b) In the tropical Indonesia fires are often related to the drought during El Niño events. It is assumed that on Borneo 5 Mio ha of forest have been affected during the El Niño 1982/83, which is more than the area of Switzerland. During the El Niño 1997/1998 the situation was even worse. About 5 Mio ha were burnt only in the province East Kalimantan, 6.5 Mio ha in total Borneo. All the fires of 1997-1998 were human-caused. The majority of the fires were due to land speculation and large-scale forest conversion as a result of inadequate and unenforced land use policies.

c) In Russia more than a quater of the size of whole Europe are covered by forests and partially forested areas (> 2500 Mio ha or 25 Mio km²), most of them boreal forest dominated by conifers. Due to successful fire management the area of burnt and dead land could be reduced from estimated 70 Mio ha in 1991 to about 30 Mio ha in 1991. But the statistics are not complete.

d) The rainforest in Brazil experiences since decades a continuous deforestation by man. Here evergreen forest, which naturally would not burn, is cleared by humans and converted irreversibly into agricultural land. 400,000 km² have been cleared until 1988, about 35,000 km² per year is the estimated rate. In total more than the area of France has been destroyed up to now, releasing huge emissions to the atmosphere, which are not taken up again by regrewing vegetation.

(Data from FAO report 2000)

http://www.fire.uni-freiburg.de/programmes/un/fao/Wp55_eng.pdf  (6 MB)

Sobre esta página:

- Autor: S. Ancot - University of Nürnberg - Germany, Elmar Uherek - MPI Mainz - Germany
- revisión científica:
- revisión pedagógica: Dr. Schrettenbrunner / J. Heres
- última actualización: 2004-01-13