Study: Climate change altering Tahoe forest

Worldwide, the most recognizable symbol of global climate change may be the polar bear: As polar ice caps recede, the giant bears retreat farther into the Arctic.

In the Northern Sierra Nevada, the symbol could be the massive red fir tree.

As the Sierra Nevada warms, the cold-weather giants are dying off in their lower-altitude stands, making way for trees such as oaks, which prefer the heat, said a researcher from the University of California, Berkeley. The trees generally grow above 4,200 feet.

Ecologist Patrick Gonzalez recently completed a fives year study in the Tahoe National Forest on how climate change affects vegetation along with researchers from the United States Forest Service.

“The study found when one type of forest dies off, another type of forest starts,” Gonzalez said. “We expect, with the warming of the Earth, that vegetation zones like oak woodland (right) would start to appear at higher elevations.”

Researchers studied a tract of the national forest at different elevations north of Downieville. Cold-weather trees such as red firs started dying off at a higher rate than in the previous 75 years, and as they died, oaks and the Douglas firs began to take root at higher altitudes.

The vegetation shift could increase wildfires in the Tahoe National Forest, Gonzalez said.

“In areas where California black oak mixes with fire-sensitive conifers (such as red firs), periodic fires keep the oaks dominant. With climate change, fire frequency may increase in many areas,” Gonzalez said.

Part of the study was published in a worldwide report last week on vegetation shifts, showing cold-weather plants across the globe are receding to higher elevations and deeper into the poles. The full study on the Tahoe National Forest is in manuscript form and doesn't have a release date yet, Gonzalez said.

Source:
The Union.com, "Study: Climate change altering Tahoe forest", accessed June 8, 2010