Effects of Deforestation in Amazonia

Climatic changes caused by deforestation can be a global problem as well as local. These changes can be measured in precipitation, evapotranspiration and cloud cover. The total amount of deforestation in 1988 was 1.5x104 km2/yr (Werth and Avisser, 2002). This caused a reduction in annual precipitation (between 220-640 mm/yr), a reduction in evaporation (between 164-500 mm/yr) and an increase in surface temperatures (between 0°C-3°C) (Werth and Avisser, 2002). Figure 2 shows the “significant decrease in rainy season precipitation” and little change in the dry season after an area as been deforested. This decrease in precipitation during the rainy seasons directly affects the

Hydrological System

rainforest as it will inhibit the growth of the next generation of flora in the Amazon. Deforestation also causes a reduction in the “vertical average moisture convergence” (Werth and Avisser, 2002) which implies that there is a connection between deforestation in the Amazon and global atmospheric flow. This has been shown to cause large reductions in the total amount of water in the global hydrological cycle and cloud cover. Deforestation effects are highest at a localised scale and decrease further away from the source.

Biodiversity and Soil Degradation

When forests are cut down into smaller blocks the “edge effects alter flora and fauna within rainforests” (Butler, 2006). Fragmented patches are exposed to dry winds which cause the number of tree falls to increase. These gaps in the canopy effect the ability of the rainforest to maintain humidity, temperature and heat of the forest floor. These effects then influence the species living there and cause a reduction in diversity. Many rare species living deep in the rainforest are unable to cope with the new environmental conditions and are eventually replaced by more common species. Scientists also suggest that continued rainforest loss could turn the Amazon into a savannah landscape through processes such as sandification and soil degradation in deforested areas. Amazonian soils “consist of up to 80 per cent or even more of fine quartz” and do not retain nutrients well. This is because the only clay mineral present is kaolinite which has a low absorption capacity. The forest has a dense mat of roots above the ground which filters nutrients before they can enter the soil. Deforestation interrupts this closed system of recycling nutrients and exposes the soil to rain and erosion. The soil is heated and desiccated in the dry season which transforms it into a nonporous “dust bowl”. The finer clay particles are washed away in the rainy season, leaving coarser and heavier sand particles behind which reduces the soil’s water retention. Tree seedlings cannot develop in the new sandy soil conditions which prevents the growth of the forest.

had no immunity to and it was estimated that 20% of the Yanomami population, around 1500, died in the following epidemic (Bier ,2005).

The construction of the road allowed mining and timber companies deeper access into the jungle and this brought with it its own unique troubles. During the 1980-90s heavily armed Brazilian gold miners (‘garimpeiros’ in Portugese) and lumbermen went deep into Yanomami and fought with their resistance. A study conducted by researchers at the University of Maryland estimates that over 100 Yanomami have been murdered since the discovery of oil in indigenous lands (MAR)

The Yanomami Tribe

In 1973 construction began on the Northern Circumferential Highway as part of the National Integration Plan (OoAS, 1985). This involved cutting down large swathes of the rainforest to build the new expressway, much of which fell inside Yanomami territory. This influx of ‘foreign’ invaders brought with it a wave of violence and disease to the previously self sustaining Yanomami people. The new workers carried malaria infections that the indigenous tribes

The Amazon rainforest is, according to Greenpeace International, the most diverse ecosystem on earth with “more than 60,000 plant species, 1,000 bird species, and more than 300 mammal species” that are

known to the scientific world. There are, however, most definitely countless more undiscovered species deeper in the rainforest. For decades the Amazon has been affected by concentrated logging, mining and construction, cutting huge swathes through the jungle. This poster aims to shed light on the main

effects deforestation causes in the Amazon .

Carbon Emissions Deforestation in the Amazon accounts for “15-35% of annual fossil fuel emissions” (Houghton, 2005). The total amount of emissions are dependent on the rate of deforestation (see Figure 4) occurring and the biomass. It has been calculated that “the amount of carbon held in trees is 20-50 times higher in forests than in cleared lands” (Houghton, 2005). Deforestation causes carbon, originally held in forests, to be released into the atmosphere. This is either immediately through the burning of vegetation or slowly through the decomposition of soil and cleared vegetation. It has been found that greenhouse gas emissions from deforestation add up to 25% of the global anthropogenic greenhouse emissions. If the trend continues, tropical deforestation will eventually

contribute to “50% of total anthropogenic greenhouse emissions” (Houghton, 2005). Along with carbon release, deforestation also releases methane, nitrous oxide and other chemically reactive gasses. These extra gases are indirectly released from deforestation through the conversion of forests to agricultural land, ranching and mining.

Figure 2: This graph shows deforestation against carbon emissions. A correlation can be seen http://www.grida.no/graphicslib/detail/annual-deforestation-in-the-amazon-and-resulting-co2-emissions_0d8b#

Figure 1: Shows precipitation before (blue) and after (red) deforestation. A notable decrease is seen in the summer months. http://lba.cptec.inpe.br/publications/LBA_JGR_Special_Issue_Oct_2002/Local_and_global_effects_Amazon_deforestation_Roni_Avissar_JGR_LBA_Oct2002.pdf

Sandification and soil degradation in the Amazon http://earthcool.com/deforestation.htm

Members of the Yanomami tribe preparing food. http://edubuzz.org/laurensblog/yanomami-tribe/

A large rural population in the Amazon relies on forest products such as Brazil nuts, rubber, oils, subsistence agriculture and fishing for survival (UNRISD, 1992). One such population is the Seringueiros (‘rubber tappers’). Deforestation often had devastating consequences on the Seringueiros, such as the destruction of rubber trees, the source of their livelihood. State policies encouraged cattle ranching with incentives and land ownership changes which deprived the Seringueiros of access to the rubber trees and often resulted in the people’s expulsion. Similarly, pollution and restricted access to rivers and game created a decrease in the availability of fish and meat which was often their only source of protein. Many Seringueiros had to move to cities after being expelled in land conflicts and often ended up in the slums of cities such and Rio Blanco and Porto Velho. The registered population increase in these cities was reportedly “over 10 per cent annually between 1970 and 1980” (UNRISD, 1992). The slums often lacked health, education and employment facilities which was due to the rapid urbanisation. Most of the Seringueiros lacked urban skills so unemployment was common.

References Bier, S. 2005. Conflict and Human Rights in the Amazon: The Yanomami Available from http://www1.american.edu/ted/ice/yanomami.htm [accessed 26/04/2012] Butler, R. 2006. Fragmentation reduces biodiversity in the Amazon rainforest and worsens global warming. Available from: http://news.mongabay.com/2006/1127-stri.html [accessed 30/04/2012] Houghton, R. 2005. The Woods Hole Research Center In: P. Moutinho and S. Schwartzman (eds), Tropical Deforestation Climate Change, Washington: Instituto de Pesquisa Ambiental da Amazônia, pp. 13 The Minorities at Risk (MAR), http://www.cidcm.umd.edu/mar/ [accessed 26/4/2012] Organization of American States (OoAS). 1985. Available from http://www1.american.edu/ted/ice/yanomami.htm [accessed 26/04/2012] Sioli, H. 1985. Effects of Deforestation in Amazonia. The Geographical Journal. 151, pp. 197-203. The United Nations Research Institute for Social Development (UNRISD). 1992. The Social Dynamics of Deforestation in the Brazilian Amazon: An Overview. Geneva :UNRISD publications, 23-26 pp. Werth, D. and Avisser, R. 2002. The local and global effects of Amazon deforestation. Journal of geophysical research, 107, pp. 1-7.

The Seringueiros

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