However, this is a fallacy. In nature, photosynthesis does not act alone. It is coupled with the biochemically opposite process of respiration. While photosynthesis reduces the amount of carbon in the air, respiration increases it. For any ecosystem, the resulting mass balance is: Net Production = Gross Production - Respiration. In tropical rainforests, both photosynthesis and respiration are taking place at great rates. In many cases, respiration equals gross production, resulting in net production being almost zero. The high rates of respiration are due to well developed food chains, which promote biodegradation. Soils in the Amazon rainforest have been heavily leached by runoff and are, therefore, poor in nutrients. Nutrient recycling tends to be the rule rather than the exception. Thus, the Amazon rainforest is not likely to help in taking up excess carbon from the air.