Skip to main content
ad info

 
CNN.com  nature
  Editions | myCNN | Video | Audio | Headline News Brief | Feedback  

 

  Search
 
 

 
NATURE
TOP STORIES

New hurdles hamper Galapagos oil spill cleanup

Insight, Prius lead the hybrid-powered fleet

Picture: Indonesia's Merapi volcano erupts

(MORE)

TOP STORIES

Up to 2,000 killed in India quake; fear of aftershocks spreads

Clinton aide denies reports of White House vandalism

New hurdles hamper Galapagos oil-spill cleanup

Two more Texas fugitives will contest extradition

(MORE)

MARKETS
4:30pm ET, 4/16
144.70
8257.60
3.71
1394.72
10.90
879.91
 


WORLD

U.S.

POLITICS

LAW

TECHNOLOGY

ENTERTAINMENT

HEALTH

TRAVEL

FOOD

ARTS & STYLE



(MORE HEADLINES)
*
  E-MAIL:
Subscribe to one of our news e-mail lists.
Enter your address:
Or:
Get a free e-mail account

 DISCUSSION:
 message boards
 chat
 feedback

  CNN WEB SITES:
CNN Websites
 AsiaNow
 En Español
 Em Português
 Svenska
 Norge
 Danmark
 Italian

 FASTER ACCESS:
 europe
 japan

 TIME INC. SITES:
 CNN NETWORKS:
Networks image
 more networks
 transcripts

 SITE INFO:
 help
 contents
 search
 ad info
 jobs

 WEB SERVICES:
CNN e-store


Vicious cycle: Global warming feeds fire potential

Global warming may be fueling the fire cycle of America's desert ecosystems. Pictured here is a typical profusion of Bromus and other annual species in a wet year at the FACE facility in the Nevada desert  
ENN



Global warming may greatly accelerate the fire cycle in the desert ecosystem of North America, according to a study published today in the journal Nature.

Elevated carbon dioxide levels, the result of increased fossil fuel burning, can alter the delicate balance of grasses in desert areas, the report notes. This finding may have major implications for the biodiversity and health of desert ecosystems in the western United States.

"This could be a real problem for land managers," said Stan Smith, a professor of biology at the University of Nevada in Las Vegas and lead author of the study.

The scientists based their research on the assumption that CO2 emissions will increase by 50 percent over the next 50 years. Using free-air CO2 enrichment technology, they examined the impact of such an increase on four plant communities in the Mojave Desert ecosystem.

  ALSO
 

Both plant density and biomass increased at elevated CO2 levels, which coincided with high precipitation years. Following the 1998 El Niño rain cycle, Nevada experienced one of the worst fire seasons on record, with the loss of more than 1.5 million acres of land. "Recent studies suggest that the El Niño high rain cycle will intensify with climate change," Smith noted.

Increased CO2 especially influenced the survival of invasive plants.

Most productive among the plants studied was a non-native grass commonly known as red brome. The grass, which thrives in hotter deserts of the West and is suspected to have helped flame recent fires in the region, is a close relative of cheatgrass.

Stan Smith, a professor of biology at the University of Nevada in Las Vegas, pauses behind creosote bushes in the UNLV greenhouse  

"What red brome does is provide a lot of fine fuels for fires to get started and carry through," said study co-author Bob Nowak.

"(Red brome) is capable of carrying fire across the bare zones between shrubs, and thus burn both the grasses and shrubs," Smith added. "Prior to the introduction of these exotic grasses, there were few plant species that could create such a continuous cover, and so these desert scrub ecosystems did not historically burn."

When cheatgrass and fire conspire, they continue to wipe out native grass species. With each blaze, the fire-savvy annual endures, while native species are choked out.

"The dominance of the exotic grass species bromus tectorum (cheatgrass) which has invaded many thousands of acres in western North America may be enhanced by elevated CO2 and thus alter competitive balance and the fire cycle in semi-arid shrub steppe environments," the authors write. "If these predictions are realized, biodiversity in arid and semi-arid ecosystems could be significantly reduced."

Red brome has the same potential. "The clear picture we are seeing is that this exotic annual could become much more dominant in the ecosystem and could enhance the fire cycle," Smith said.

Conservation groups also cite climate change as one of the causes behind the 2000 fire season, which ravaged more than 5 million acres in the western United States.

Smith allows that Nevada's fire cycle in relation to invasive grasses is very different from factors in the 2000 forest fires. But he, too, believes that climate change may have played a role in the recent disaster.

"In a lot of ways the experiment we're doing is a look into the future, and the future doesn't look so good," Nowak said. "What we are already seeing in the northern Nevada Great Basin with cheatgrass, we are going to see more and more in southern Nevada in the Mojave with red brome."

Copyright 2000, Environmental News Network, All Rights Reserved




RELATED STORIES:
Report strengthens link between pollution, global warming
October 27, 2000
Clouds' role in global warming studied
October 9, 2000
Report: Shorter lake and river ice seasons confirm global warming
September 7, 2000
NASA urges practical solutions for reducing greenhouse gases
August 16, 2000

RELATED ENN STORIES:
Alien species: A slow motion explosion
Blame it on El Niño: Are we ignoring the early signs of global warming
World's habitat feeling the heat of climate change
Cheatgrass chokes out native desert plants
BLM to intensify war on weeds

RELATED SITES:
Nature
Stan Smith
Climate Change Campaign
National Interagency Fire Center
Nevada Desert FACE (Free-Air-Carbon dioxide-Enrichment) Facility

Note: Pages will open in a new browser window
External sites are not endorsed by CNN Interactive.

 Search   


Back to the top   © 2001 Cable News Network. All Rights Reserved.
Terms under which this service is provided to you.
Read our privacy guidelines.