Large, old trees grow fastest

Alan McNeil passed on this very interesting item. Think tree growth slows with maturity? Not according to a recent article in Nature.

The USGS, which had a lot to do with this study, put out a press release. Here’s the lead-in . . . .

Trees do not slow in their growth rate as they get older and larger — instead, their growth keeps accelerating, according to a study published today in the journal Nature.

“This finding contradicts the usual assumption that tree growth eventually declines as trees get older and bigger,” says Nate Stephenson, the study’s lead author and a forest ecologist with the U.S. Geological Survey. “It also means that big, old trees are better at absorbing carbon from the atmosphere than has been commonly assumed.”

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 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.

“In human terms, it is as if our growth just keeps accelerating after adolescence, instead of slowing down,” explains Stephenson. “By that measure, humans could weigh half a ton by middle age, and well over a ton at retirement.”

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