CORVALLIS, Ore. New research concludes that a one-two punch of drought and mountain pine beetle attacks are the primary forces that have killed more than 2.5 million acres of pinyon pine and juniper trees in the American Southwest during the past 15 years, setting the stage for further ecological disruption.
The widespread dieback of these tree species is a special concern, scientists say, because they are some of the last trees that can hold together a fragile ecosystem, nourish other plant and animal species, and prevent serious soil erosion.
The major form of soil erosion in this region is wind erosion. Dust blowing from eroded hills can cover snowpacks, cause them to absorb heat from the sun and melt more quickly, and further reduce critically-short water supplies in the Colorado River basin.
The findings were published in the journal Ecohydrology by scientists from the College of Forestry at Oregon State University and the Conservation Biology Institute in Oregon. NASA supported the work.
"Pinyon pine and juniper are naturally drought-resistant, so when these tree species die from lack of water, it means something pretty serious is happening," said Wendy Peterman, an OSU doctoral student and soil scientist with the Conservation Biology Institute. "They are the last bastion, the last trees standing and in some cases the only thing still holding soils in place."
"These areas could ultimately turn from forests to grasslands, and in the meantime people are getting pretty desperate about these soil erosion issues," she said. "And anything that further reduces flows in the Colorado River is also a significant concern."
It's not certain whether or not the recent tree die-offs are related to global warming, Peterman said. However, the 2007 report of the Intergovernmental Panel on Climate Change projected that while most of the United States was getting warmer and wetter, the Southwest will get warmer an
|Contact: Wendy Peterman|
Oregon State University