From: Allison Winter, ENN
Published September 27, 2012 10:16 AM

Mid-Elevation Mountain Forests are Sensitive to Climate Change

Decreased snow cover in the Northern Hemisphere is one piece of evidence that climate change is occurring. So with this decline, how will mountain biomes be affected and which areas will become most vulnerable to these changes?

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According to researchers at the University of Colorado Boulder, mid-elevation mountain ecosystems at altitudes between 6,500 and 8,000 feet are most sensitive to affects associated with climate change.

The study team used both satellite images and ground measurements to identify the threshold where forests transition from using moisture as their primary source of sustenance to using sunlight and temperature. About half of the mid-elevation forest greenness measured was attributed to the snow accumulations from the previous winter, with the other half due to conditions such as soil depth, soil nutrients, temperature and sunlight.

Changes related to decreasing snowpack could cause forests to lose an important source of water and nutrients needed during the growing season. Snowpack is also responsible for feeding streams and rivers as they melt which in turn provide water for downslope communities.

"Our results provide the first direct observations of the snowpack-forest connections across broad spatial scales," said Molotch, a research scientist at CU-Boulder's Institute of Arctic and Alpine Research. "Finding the tipping point between water-limited forests and energy-limited forests defines for us the region of the greatest sensitivity to climate change -- the mid-elevation forests -- which is where we should focus future research."

Climate studies indicate the snowpack in mid-elevation forests in the Western United States and similar forests around the world has been decreasing in the past 50 years because of regional warming.

Molotch states, "If snowpack declines, forests become more stressed, which can lead to ecological changes." These changes can include that include tree mortality, increased vulnerability to forest fires, and beetle outbreaks.

The researchers predict that the tipping-point elevation is likely to migrate up the mountainsides as climate warms. This is especially interesting because while other plant and animal species may be able to adapt by migrating farther north, alpine species are limited to the mountain range and will only be able to shift in altitude rather than latitude.

Being able to identify this range is not only important to human recreational activities such as camping, hiking, skiing, and fishing, but these mid-elevation forests provide habitat to a specialized range of plant and animal species.

For more information see University of Colorado, Boulder

Alpine forest image via Shutterstock.

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