Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Drought in 2001-2002 Fueled Rocky Mountain Pine Beetle Outbreak

06.11.2012
Reduced precipitation in the southern Rockies turned outbreak into epidemic

Results of a new study show that episodes of reduced precipitation in the Southern Rocky Mountains, especially during the 2001-2002 drought, greatly accelerated a rise in numbers of mountain pine beetles. The overabundance is a threat to regional forests.

The research is the first to chart the evolution of the current pine beetle epidemic in the southern Rocky Mountains.

It compared patterns of beetle outbreaks in the two primary host species, the ponderosa pine and lodgepole pine, said University of Colorado at Boulder (CU-Boulder) researcher Teresa Chapman.

A paper on the subject is published in the current issue of the journal Ecology. Chapman is lead author of the paper; co-authors include CU-Boulder scientists Thomas Veblen and Tania Schoennagel.

The National Science Foundation (NSF) funded the research.

"This study confirms that warming temperatures and drought are likely triggers of the widespread bark beetle outbreaks that have devastated forests over vast areas of the West," said Richard Inouye, program director in NSF's Division of Environmental Biology.

"It also suggests why bark beetle outbreaks may vary for two different tree species," he said, "and how different forests may be more or less susceptible to these insects that are transforming mountain landscapes."

The current mountain pine beetle outbreak in the Southern Rockies--which ranges from southern Wyoming through Colorado and into northern New Mexico--is estimated to have affected almost 3,000 square miles of forests.

While the 2001-2002 drought in the West played a key role in pushing the pine beetle outbreak into a true regional epidemic, the outbreak continued to gain ground even after temperature and precipitation levels returned to levels nearer the long-term averages.

The beetles decimated lodgepole pine forests by moving into wetter and higher elevations and into less susceptible tree stands--those with smaller-diameter lodgepoles that share space with other tree species.

"In recent years some researchers have thought the pine beetle outbreak in the Southern Rocky Mountains might have started in one place and spread from there," said Chapman.

"What we found was that the mountain pine beetle outbreak originated in many locations. The idea that the outbreak spread from multiple places, then coalesced and continued spreading, really highlights the importance of the broad-scale drivers of the pine beetle epidemic, like climate and drought."

Mountain pine beetles range from Canada to Mexico and are found at elevations from sea level to 11,000 feet. These native insects have shaped the forests of North America for thousands of years by attacking old or weakened trees, resulting in younger forests.

The effects of pine beetle overpopulation are especially evident in recent years on Colorado's Western Slope, including Rocky Mountain National Park, with a particularly severe epidemic occurring in Grand and Routt counties.

The most recent mountain pine beetle outbreak began in the 1990s, primarily in scattered groups of lodgepole pines at low elevations in areas of lower annual precipitation.

Following the 2001-2002 drought, the outbreak was "uncoupled" from the initial weather and landscape conditions, triggering a rise in beetle populations on the Western Slope and propelling the insects over the Continental Divide into the Northern Front Range to infect ponderosa pine, Chapman said.

The current pine beetle epidemic in the Southern Rocky Mountains also was influenced by extensive forest fires that ravaged Colorado's Western Slope from roughly 1850 to 1890.

Lodgepole pine stands completely burned off by the fires were followed by huge swaths of seedling lodgepoles that eventually grew side-by-side into dense mature stands, making them easier targets for the pine beetles.

"The widespread burning associated with dry years in the 19th century set the stage by creating vast areas of trees in the size classes most susceptible to beetle attack," said Chapman.

Veblen said a 1980s outbreak of the pine beetle in Colorado's Grand County ended when extremely low minimum temperatures were reached in the winters of 1983 and 1984, killing the beetle larvae.

But during the current outbreak, minimum temperatures during all seasons have been persistently high since 1996, well above the levels of extreme cold shown to kill beetle larvae in laboratory experiments.

"This implies that under continued warming trends, future outbreaks will not be terminated until they exhaust their food supply--the pine tree hosts," said Veblen.

Chapman said there has been a massive and unprecedented beetle epidemic in British Columbia, which also began in the early 1990s and now has affected nearly 70,000 square miles.

"It is hard to tell if this current beetle epidemic in the Southern Rockies is unprecedented," she said. "While warm periods in the 16th century may have triggered a large beetle epidemic, any evidence would have been wiped out by the massive fires in the latter 19th century."

The rate of spread of the mountain pine beetle in lodgepole pine forests has declined in the southern Rocky Mountains during the past two years because of a depletion of host pine population.

But surveys indicate that the rate of beetle spread in ponderosa pine forests on the Front Range has increased sharply over the past three years.

The current study suggests that under a continued warmer climate, the spread of the beetle in ponderosa pines is likely to grow until that food source also is depleted.

"Our results emphasize the importance of considering different patterns in the population dynamics of mountain pine beetles for different host species, even under similar regional-scale weather variations," said Chapman.

"Given the current outbreak of mountain pine beetles on the Front Range, the effect on ponderosa pines is certainly something that needs further study."

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Jim Scott, University of Colorado at Boulder (303) 492-3114 jim.scott@colorado.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov
http://nsf.gov/news/news_summ.jsp?cntn_id=125934&org=NSF&from=news

More articles from Ecology, The Environment and Conservation:

nachricht Managing an endangered river across the US-Mexico border
18.07.2016 | International Institute for Applied Systems Analysis (IIASA)

nachricht The European pet trade is jeopardising the survival of rare reptile species
13.07.2016 | Helmholtz-Zentrum für Umweltforschung - UFZ

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Mapping electromagnetic waveforms

Munich Physicists have developed a novel electron microscope that can visualize electromagnetic fields oscillating at frequencies of billions of cycles per second.

Temporally varying electromagnetic fields are the driving force behind the whole of electronics. Their polarities can change at mind-bogglingly fast rates, and...

Im Focus: Continental tug-of-war - until the rope snaps

Breakup of continents with two speed: Continents initially stretch very slowly along the future splitting zone, but then move apart very quickly before the onset of rupture. The final speed can be up to 20 times faster than in the first, slow extension phase.phases

Present-day continents were shaped hundreds of millions of years ago as the supercontinent Pangaea broke apart. Derived from Pangaea’s main fragments Gondwana...

Im Focus: A Peek into the “Birthing Room” of Ribosomes

Scaffolding and specialised workers help with the delivery – Heidelberg biochemists gain new insights into biogenesis

A type of scaffolding on which specialised workers ply their trade helps in the manufacturing process of the two subunits from which the ribosome – the protein...

Im Focus: New protocol enables analysis of metabolic products from fixed tissues

Scientists at the Helmholtz Zentrum München have developed a new mass spectrometry imaging method which, for the first time, makes it possible to analyze hundreds of metabolites in fixed tissue samples. Their findings, published in the journal Nature Protocols, explain the new access to metabolic information, which will offer previously unexploited potential for tissue-based research and molecular diagnostics.

In biomedical research, working with tissue samples is indispensable because it permits insights into the biological reality of patients, for example, in...

Im Focus: Computer Simulation Renders Transient Chemical Structures Visible

Chemists at the University of Basel have succeeded in using computer simulations to elucidate transient structures in proteins. In the journal Angewandte Chemie, the researchers set out how computer simulations of details at the atomic level can be used to understand proteins’ modes of action.

Using computational chemistry, it is possible to characterize the motion of individual atoms of a molecule. Today, the latest simulation techniques allow...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

GROWING IN CITIES - Interdisciplinary Perspectives on Urban Gardening

15.07.2016 | Event News

SIGGRAPH2016 Computer Graphics Interactive Techniques, 24-28 July, Anaheim, California

15.07.2016 | Event News

Partner countries of FAIR accelerator meet in Darmstadt and approve developments

11.07.2016 | Event News

 
Latest News

Hey robot, shimmy like a centipede

22.07.2016 | Information Technology

New record in materials research: 1 terapascals in a laboratory

22.07.2016 | Physics and Astronomy

University of Graz researchers challenge 140-year-old paradigm of lichen symbiosis

22.07.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>