By Victor Miguel Ponce

Through photosynthesis, all forests take carbon dioxide from the air and incorporate the carbon molecule into organic matter. In tropical rainforests such as the Amazon, great quantities of carbon are fixed into cellulose to become part of the biosphere. This has supported the argument that preservation of the Amazon rainforest will ensure the removal of the excess carbon now in the atmosphere due to the burning of fossil fuels.

The fallacy of this argument is apparent when it is realized that photosynthesis never acts alone. In nature, photosynthesis is coupled with the biochemically opposite process of respiration. Photosynthesis reduces the amount of carbon in the air, while respiration increases it. For any ecosystem, a mass balance requires the following:

Net Production = Gross Production - Respiration

In tropical rainforests, gross production (i.e., the amount of photosynthesis) and respiration take place at about the same rate. In many cases, respiration is the same as gross production, resulting in net production being equal to zero. The high rates of respiration are due to the well developed food chains, which promote efficient biodegradation and fast nutrient recycling.

The soils of the Amazon rainforest have been heavily leached through millennia and are, therefore, poor in nutrients. The nutrients that exist are stored in the canopy, with fast nutrient recycling being the rule. Effectively, a rainforest sequesters very little carbon. Through efficient food chains, the organic matter biodegrades quickly, the nutrients are recycled promptly, and the carbon dioxide is released back to the atmosphere almost as fast as it is uptaken. Thus, the Amazon rainforest is not likely to help in removing excess carbon from the air.