Biggest Trees Sequester the Most Carbon, Study Reveals

Findings contradict years of speculation that young trees gain mass faster than older ones—a common excuse for clear-cutting.

Large trees gain mass—and sequester carbon—at a much higher rate than small trees, a new study from the U.S. Geological Survey (USGS) reveals. Scientists took their own measurements but also used large amounts of existing data from other research to learn more about the growth rates of more than 400 species of trees. Almost all of the species (97%) saw faster growth rates among their largest trees, according to Nathan Stephenson at USGS.

The findings run counter to what Stephenson calls a myth about older trees—that they store huge amounts of carbon but don’t continue to sequester more carbon at a very high rate. On the contrary, he told Nature reporter Jeff Tollefson, “Trees have the equivalent of an adolescent growth spurt, but it just keeps going.”

Some logging companies have used this “myth” as a reason to harvest old-growth trees.

The practical implications of the findings are not yet clear, however. Stephenson says that young forests as a whole do sequester carbon at higher rates than old forests, simply because there are so many more trees. But, writes Tollefson, “the research could help scientists to develop better models of how forests function and their role in regulating the climate.”

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Nature News

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