BY DR. JOSE PALU-AY DACUDAO
(Why Chernobyl mammalian wildlife survive)
IN THE previous articles, we identified major human-made processes that sequester carbon dioxide away from the atmosphere.
First is responsible forestry. Second is charring.
As an example of responsible forestry in the Philippines, we mentioned falcata plantations in Mindanao island.
Falcata (Falcataria falcata) is a fast-growing tree of the nitrogen-fixing legume family (Fabaceae). Since it is a nitrogen fixer as is most of the rest of its family (with which we are more familiar with as the beans we often eat), it doesn’t need any nitrogenous fertilizer and grows very fast as long as it has access to plenty of water.
In brief, falcata trees are ravenous carbon dioxide gulpers, transforming it massively into lignin. After seven to 10 years, these lignin-rich trees in a plantation are harvested and cut mostly into plywood and other woody stuff that makes up houses and woody infrastructures. Other products from falcata are match-sticks and match boxes, other wooden boxes, furniture, and paper.
As long as these woody infrastructures are not burned down or biologically decay, they represent a carbon sink. (As noted previously, lignin is very difficult to biodegrade.) Therefore, falcata forestry is a process that sequesters carbon away from the air, lessening atmospheric carbon dioxide, as long as the products are not burned or biologically decomposed.
Some trees are commercially planted not for their wood, but for other products. An example is natural rubber. Rubber is made up of polymers of the carbon-rich compound isoprene C5H8. Rubber is hard to biologically decompose because it is insoluble in water. As in the case of lignin, if natural rubber is not burned or does not biologically decay, rubber production by plantation rubber trees acts as a carbon sink.
A basic principle is that commercial trees or plant products that are not burned or decomposed act as carbon sinks.
Note: Synthetic rubber and plastics are made from petroleum. Petroleum is a fossil fuel whose carbon got fixed from ancient atmospheres millions of years ago, and not in a recent geological instant (let us say seconds to a thousand years). Thus, using petroleum (or other fossil fuels) to make products does not sequester carbon dioxide away from the present atmosphere.
How exactly do falcata trees (and other woody plants) sequester carbon dioxide away from the atmosphere?
Strictly speaking, the main organic substance that photosynthesis ultimately produces to make wood woody is lignin, but in past articles, we often took the compound C6H12O6 to represent it for simplicity’s sake.
An oft-quoted formula for lignin is C31H34O11. Lignin is made by plants from the amino acid phenylalanine, which has a closed-ring aromatic benzyl side chain. Phenylalanine is more famous among medical people as an essential amino acid for humans. (To be continued)/PN
