April 11, 2013
Trees Will Not Grow Up Into Alpine Level, Study Says
Lee Rannals for redOrbit.com — Your Universe Online
Scientists thought forest lines on mountains would start growing in higher elevations as the planet's temperature began to rise due to global warming, but new research out of the University of Calgary found it not to be the case.
The team found local geologic and geomorphic conditions would limit trees being established at higher elevations on mountains. They wrote in the Proceedings of the National Academy of Sciences temperature alone couldn´t explain high-elevation tree cover over a 38 square mile area in the Canadian Rockies.
"You can't just take a mountain range and say that in every place the tree line is going up," says Edward Johnson, professor of Biological Sciences and study co-author with then-postdoctoral researcher, Marc Macias-Fauria — now at Oxford University. "We have to caution that it depends on how much suitable habitat there is above where the tree line is now."
The team looked at tree cover in the Marmot Creek Research Watershed, which is next to the Nakiska ski hill in Kananaskis Country, west of Calgary. They used a supercomputer at Oxford University to run regional and global computer climate models, and also performed remote sensing and on-the-ground investigations of the area.
The scientists used the model to help forecast tree cover based on moderate climate warming predicted for the late 21st century. Johnson said even with warmer temperatures, there are lots of places in the alpine where the conditions are not suitable for trees.
"Between six to 18 percent of the present alpine area is either too steep, has bedrock, cliffs and talus or some other local terrain conditions that will limit trees being established," he adds.
The team plans to develop a new model that includes all the local geologic and geomorphic factors, which identify the inter-related causes of why trees do or do not get established in specific areas.
A study released in 2011 of some evergreen trees in Alaska shows at least some forests may be adapting to a warming climate. Researchers from this study found trees tended to grow as the arctic faced rapid warming.
“I was expecting to see trees stressed from the warmer temperatures,” said study lead author Laia Andreu-Hayles, a tree ring scientist at Columbia University´s Lamont-Doherty Earth Observatory. “What we found was a surprise.”