Rainforest deforestation

Land use changes in the tropics have resulted in a landscape characterized as a mosaic of logged forests, cleared fields, and successional forests. This results in the transformation from extremely fire resistant rainforest ecosystems to anthropogenic landscapes in which fire is a common event (16, 17), Fires occur in disturbed tropical forests because deforestation has a dramatic effect on microclimate. Deforestation results in lower relative humidities, increased wind speeds, and increased air temperatures. In addition, deforestation results in increased quantities of biomass that are susceptible to fire. This biomass may be in the form of forest slash, leaf litter, grasses, lianas or herbaceous species (16, 18). 

Similar results were reported in deforested Amazonian rainforests (66). Within three years following forest clearing and burning, nutrient concentrations of soil leachates had returned to levels typical of primary forests of the area. A combination of high rates of immobilization and storage by successional vegetation, coupled with a decline in easily decomposable substrates, was attributed to the reduction in leaching losses. 

The additional and steadily increasing demand for biofuels could lead to a situation where production of biomass derived fuels finally compete with food production. People who can afford cars can pay more for biomass for fuels than people in non-industrialised countries can pay for food production. Fertile soil in non-industrial countries might then be used for energy crops instead of food. This may eventually lead to a situation where only bad soil is left for food crops and the poor, which in addition would eventually also lead to further deforestation of the World s rainforests. 

In comparison, the average tree consumes only 1 ton of COz in a lifetime, and an acre of rainforest consumes about 500 tons yearly. When agribusiness, the ethylene industry, or pulp and paper corporations turn forests or rainforests into farmland, they also destroy an effective consumer of COz. The world s fastest-disappearing forests are in Indonesia, where they are cut down either to make paper pulp or to be replaced by palm oil plantations. Palm oil is mostly used to make biodiesel fuels. Tropical deforestation not only results in COz emissions (20% of the global total), but it also poisons the rivers. 

Meir, P., J. Grace, A. Miranda, and J. Lloyd. 1996. Soil respiration in a rainforest in Amazonia and in cerrado in central Brazil. Pages 319-329. in J. H. C. Gash, C. A. Nobre, J. M. Roberts, and R. L. Victoria, editors. Amazonian deforestation and climate. Institute of Hydrology, London. 

Forti, M. C., C. Neal, and A. Jenkins. 1995. Modeling perspective of the deforestation impact in stream water quality of small preserved forested areas in the Amazonian rainforest." Water, Air, and Soil Pollution 79 325-337. 

Another approach is to increase carbon dioxide uptake by forests to reverse the effects of severe deforestation of the last 150 years. It has been estimated that a rapidly growing rainforest can remove 4-7kg/m year of carbon dioxide from the atmosphere, as compared to a typical crop uptake of 0.8-1.6kg/m year. Thus, vigorous reforestation could assist in increasing the photosynthetic removal of carbon dioxide from the atmosphere [59]. Annual crops also perform photosynthetic uptake of carbon dioxide, but consumption and metabolism of the product(s) and prompt decomposition of the plant wastes promptly return the fixed carbon dioxide to the atmosphere [60]. 

R. Carrere, Gen. Coordination, The Bitter Fruit of Oil Palm Dispossession and Deforestation, World Rainforest Movement, Montevideo, 2001, www.wrm.org.uy/plantations/material/OilPalm.pdf (retrieved... 

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