Rising CO2 levels could be making trees grow like crazy

Washington, December 5 (ANI): A new study has suggested that the rising level of atmospheric carbon dioxide (CO2) may be fueling more than climate change, as it could also be making some trees grow like crazy.

The study, by scientists from the University of Wisconsin-Madison and the University of Minnesota at Morris (UMM), took quaking aspen, one of North America's most important and widespread deciduous trees, as its case subject.

The study shows that elevated levels of atmospheric CO2 during the past 50 years have boosted aspen growth rates by an astonishing 50 percent.

"Trees are already responding to a relatively nominal increase in atmospheric carbon dioxide over the past 50 years," said Rick Lindroth, a UW-Madison professor of ecology and an expert on plant responses to climate change.

According to the study's authors, the accelerated growth rates of aspen could have widespread unknown ecological consequences.

Aspen is a dominant tree in mountainous and northern forested regions of North America, including 42 million acres of Canadian forest and up to 6.5 million acres in Wisconsin and Minnesota.

Aspen and their poplar cousins are considered "foundation species," meaning they exert a strong influence on the plant and animal communities and dynamics of the forest ecosystems where they reside.

"We can't forecast ecological change. It's a complicated business," explained Don Waller, a UW-Madison professor of botany.

"For all we know, this could have very serious effects on slower growing plants and their ability to persist," he added.

The new study is the first to show that aspen in their native forest environments are already growing at accelerated rates due to rising ambient levels of carbon dioxide in the atmosphere.

"It's a change hiding right in front of us," said professor Christopher Cole, a biologist at UMM.

"Aspens respond to all sorts of things we had to account for - water, genetics and other factors - but the strong response to carbon dioxide surprised all of us," he added.

The study measured the growth rates of 919 trees from Wisconsin forests dominated by aspen and birch.

Trees ranging in age from 5 to 76 years old were sampled and subjected to tree-ring analysis.

Comparing the tree-ring data, a measure of annual tree growth, with records of atmospheric carbon dioxide, the researchers were able to correlate increased rates of growth with changes in the chemistry of the air. (ANI)