The older, the prettier-A A +A
Wednesday, January 29, 2014
“I THINK that I shall never see A poem lovely as a tree,” wrote American poet Joyce Kilmer, mainly remembered for a short poem titled “Trees.”
What could be prettier than an old tree? The bigger and the fatter, the better.
“It also means that big, old trees are better at absorbing carbon from the atmosphere than has been commonly assumed,” wrote forest ecologist Nathan Stephenson of the US Geological Survey in the scientific journal Nature.
In fact, trees do not slow in their growth rate as they get older and larger—instead, their growth keeps accelerating. “This finding contradicts the usual assumption that tree growth eventually declines as trees get older and bigger.”
An international team of researchers compiled growth measurements of 673,046 trees belonging to 403 tree species from tropical, subtropical and temperate regions across six continents, calculating the mass growth rates for each species and then analyzing for trends across the 403 species.
The study was a collaboration of 38 researchers from research universities, government agencies and non-governmental organizations from the United States, Panama, Australia, United Kingdom, Germany, Colombia, Argentina, Thailand, Cameroon, Democratic Republic of Congo, France, China, Taiwan, Malaysia, New Zealand and Spain.
The study was initiated by Stephenson and Das through the USGS Western Mountain Initiative and the USGS John Wesley Powell Center for Analysis and Synthesis.
The results showed that for most tree species, mass growth rate increases continuously with tree size—in some cases, large trees appear to be adding the carbon mass equivalent of an entire smaller tree each year.
Thus, our society loses plenty when centuries-old trees are felled so that poachers can transform them into charcoal.
Or for that matter, when our tropical forests are cleared to make way for sugarcane monoculture. In this era of climate change, land use conversion from forests to sugarcane monocultures is outrageous, if not downright criminal.
The continuous growth rate of centuries-old trees means that on an individual basis, large, old trees are better at absorbing carbon from the atmosphere. Carbon that is absorbed or “sequestered” through natural processes reduces the amount of carbon dioxide in the atmosphere, and can help counter-balance the amount of CO2 people generate.
“Old trees, after all, can die and lose carbon back into the atmosphere as they decompose,” says Adrian Das, a USGS coauthor. “But our findings do suggest that while they are alive, large old trees play a disproportionately important role within a forest’s carbon dynamics. It is as if the star players on your favorite sports team were a bunch of 90-year-olds.”
So tell me again, which would any of us choose? The young and the tender? Or the older and fatter trees?
Reforestation of tender seedlings or the conservation of our tropical forests and their trees? Poems are made by fools like me, but only God can make a tree.
Published in the Sun.Star Bacolod newspaper on January 29, 2014.