El Nino with its large ecological consequences. The case of fires in Borneo

Résumé du document

El Niño is a climatic phenomenon that arrives approximately during the period of Christmas in the east part of the Pacific Ocean near the west coast of South America. It involves elements from both, the Tropical Ocean and the Global Atmosphere. From a climatic point of view, El Niño is an extensive warming of the upper ocean in the tropical Eastern Pacific region and lasts for more than 5 months. This phenomenon has strong ecological consequences all over the world such as the increase in the number of tornadoes in North America, the decrease of the stream flow of a river in China or even a reduction in the Galapagos penguin populations. Nevertheless, the biggest ecological consequences are those occurring in South America and Indonesia. In Peru, El Niño causes very heavy rainfalls that lead to dangerous floods. On the contrary, there are timely droughts that lead to dramatic fires on the other side of the ocean especially in the Borneo area. These fires have a very noticeable impact on the general forest ecosystem and are the prime causes of strong haze and smoke pollution. More specifically, the wild fire that occurred in 1997-1998 caused big ecological disturbances in Borneo forests. It affected different trophic levels, more particularly the interaction of the animal population and vegetation. From the first example it can be inferred that the trees species providing fruits for sun bears had decreased a lot and therefore there was a drastic decline in the sun bear population. Next, a riverine bird saw a decrease in its population because of a disturbance in his habitat following the wild fire. Finally, the change in the vegetation after the fire had consequences on the assemblage of a particular species of butterfly. It can be inferred that, the humankind, through bad land use management techniques (which has resulted in an increase of the global warming) has been strongly responsible for these fires.

Extraits

[...] Nowadays the studies are more pointed the ecological and environmental consequences. Nevertheless, Rodriguez, Mabres et al.(2005) in their paper on the consequences of El Niño on dry forest species in Peru, still remind that the climate here is usually characterized by a warm and dry weather because of a cool current along the Peruvian coast. But during el Niño, “this arid climate is replaced by a humid tropical climate rainfall in the coastal region [ (Rodriguez, Mabres et al. 2005). [...]

[...] But, Zhang, Xu et al.(2007) go further and wonder to what degree the ENSO influences the annual maximum streamflow of the river. To this question they finally answer that there are so many other factors to take into consideration like human activities or like other climate patterns as Indian summer monsoon or East Asian monsoon. However it still remains that ENSO has a strong influence since it affects moonson circulation. Impacts on Galapagos Penguin After having considered North America and China, some studies have been done on the archipelago of Galapagos situated 1000 km Eastward from Ecuador. [...]

[...] 2002) report that these last amounts are equivalent to 13-14% of the means annual global carbon emissions from fossil fuels” Examples of specific ecological disturbances at different trophic levels, following the 1997-1998 wild fire. After having reviewed the general ecological consequences of the fire on rainforest in Borneo, this part aims to show how the wild fires, partly caused by the drought following El 1997-1998 Niño events, have had big specific ecological disturbances on communities of the rain forest ecosystem at different trophics levels. Actually, the following parts are dealing with three specific cases, firstly the impact on the sun bear fruit trees (Fredriksson, Danielsen et al. [...]

[...] 2005) of the area was subsequently affected by the fires (Fedriksson (2002) as quoted by Fredriksson, Danielsen et al., (2005). A mortality rate was then estimated for sample from half in burned forest and half in unburned forest, and this for all the tree species even those not fed upon by bears. Fredriksson, Danielsen et al.(2005) found that overall tree mortality in burned forest was extremely high, with 77,5% [more or less] 10,8% trees dead 33 months after the fore event”. [...]

[...] Nevertheless, one thing is sure; it has so many economic, social and ecological consequences. The ecological consequences are something which, as far as I am concerned, are very important and interesting to study. As a consequence, after having explained the phenomenon and its ecological consequences all over the world, we will focus on the fires that occur in Borneo and the specific ecological disturbances that it brings about. Finally, we will also provide a discussion that involved the human kind responsibilities in those fires EXPLANATION OF EL NIÑO AND ITS NUMEROUS CONSEQUENCES 1.1 A climatic phenomenon Definition First of all, the origin of the word comes from the Spanish. [...]