BY DR. JOSE PALU-AY DACUDAO
HERE IS another simplified formula (the processes are quite complicated, so we give only the end result) for anaerobic decomposition involving only glucose in which carbon dioxide and methane are produced.
C6H12O6 → 3 CO2 + 3 CH4
Taken to the extreme, in conditions where there are little or no living organisms at all, what happens? A process chemically the same as charring ultimately occurs (carbonization).
C6H12O6 → 6 H2O + 6 C
This is what essentially happens in anoxic sea bottoms and acidic anoxic peat bogs, under high temperature and pressure. Essentially, volatile water gets squeezed out, leaving solid elemental carbon behind. The end result of the above process is coal (or other carbon-rich compounds such as petroleum).
The process is facilitated if the organic material involved is already carbon-rich and hard-to-decompose by living organisms, such as lignin, which is made up (by atoms) of almost equal parts of carbon and hydrogen, with oxygen just one third of the carbon. Note that glucose only has equal parts of carbon and oxygen atoms, and with hydrogen atoms double the number of carbon atoms. Moreover, lignin is composed of aromatic (close-ring) carbon chains, stacked in layers. This makes it particularly hard for the enzymes of decomposers to get into its basic structure, thus making it highly resistant to decomposition. (That’s why wood stays as wood for a long time, compared to leaves which decompose quickly.)
We can conclude that sea bottoms and peat bogs (and other anoxic marshy places) are indeed genuine carbon sinks, just on basic biological and chemical fundamental principles.
What about the tropical forests of the equatorial regions? Mass media often portrays them as legendary giant ravenous carbon dioxide gulpers.
Indeed, they are. The caveat is that they are essentially climax communities (do not change much over time), and thus do not make much wood (lignin) anymore. The leaves they produce massively fall down and decompose. So whatever carbon dioxide the forests took from the atmosphere is returned via the decomposition of their leaves and other soft parts (cellulose and hemicellulose).
We can conclude that primary tropical forests are poor carbon dioxide net fixers, compared to anoxic peat bogs and sea bottoms.
It may come as a surprise to many people, but if one takes the chemical equations above as fundamental, young secondary forests are more massive carbon dioxide fixers than primary forests. These secondary forests are growing fast. That means they are taking carbon dioxide from the atmosphere and turning it into woody lignin, in massive amounts. Secondary growths always do. They are genuine giant ravenous carbon dioxide gulpers.
I am certainly NOT advocating for cutting down primary forests. But preserving them for being massive carbon dioxide net fixers is not a reason for their preservation, because they are not. Their importance is due to their being a genuine part of nature, and they represent biodiversity at its best. (Tropical rainforests are the most bio-diversified ecologies in the biosphere, with more species than other regions on the planet.) That is why they should be preserved. (For comments and suggestions please email to mabuhibisaya2017@gmail.com)/PN
