(Santa Barbara, Calif.) If current climate projections hold true, the forests of the Southwestern United States face a bleak future, with more severe and more frequent forest fires, higher tree death rates, more insect infestation, and weaker trees. The findings by university and government scientists are published in this week's issue of the Proceedings of the National Academy of Sciences (PNAS).
"Our study shows that regardless of rainfall going up or down, forests in the Southwest U.S. are very sensitive to temperature in fact, more sensitive than any forests in the country," said first author Park Williams, postdoctoral researcher in the Department of Geography at UC Santa Barbara. "Forests in the Southwest are most sensitive to higher temperatures in the spring and summer, and those are the months that have been warming the fastest in this area."
Past forest studies have shown that warmer temperatures are associated with wildfires and bark beetle outbreaks. "We found that up to 18 percent of forest area in the Southwest millions of acres has experienced mortality due to severe wildfires and bark beetle outbreaks in the last 20 years," said Williams.
Co-author Joel Michaelsen, a professor of geography at UCSB, said: "In order to carry out this research project, Park Williams assembled a very comprehensive data set of over 1,000 tree ring chronologies from all across the United States." Michaelsen is a dendroclimatologist a scientist who studies climate using analysis of tree rings.
"Instead of using the chronologies to reconstruct past climate patterns, as is usually done in dendroclimatic work, the relationships between growth and climate were used to study possible impacts of future climate change on forest health," said Michaelsen. "One noteworthy finding was that tree growth throughout the Southwestern U.S., while quite sensitive to precipitation variations, is also negatively impacted by warmer temperatur
|Contact: Gail Gallessich|
University of California - Santa Barbara