Paleofire database puts fire-scar and charcoal data online


Prehistoric fire records developed from tree rings and from charcoal in lake sediments are available for free for the first time. All it takes is an Internet connection.

The International Multiproxy Paleofire Database (IMPD) is a cooperative effort between those who reconstruct proxy records of past fire events from tree-ring evidence and from charcoal layers in lake sediments. The database is on the National Oceanic and Atmospheric Administration (NOAA) Web site

The paleofire database grew out of a weeklong workshop in Tucson in spring 2002. The workshop was organized by University of Arizona Laboratory of Tree-Ring Research Director Thomas Swetnam and University of Oregon Professor Cathy Whitlock, a leader in charcoal-based fire history studies. It drew 65 fire ecologists and climatologists who discussed how to merge the two different prehistoric fire records.

"I think the workshop really brought to everyone's attention how much data are available now," Whitlock said. "We're hoping the various labs will be willing and enthusiastic to contribute their data to this international effort."

So far 146 tree-ring records and 4 lake sediment records have been submitted, according to NOAA's Michael Hartman, who helps organize the database. Hartman said he hopes to add another 25 charcoal-based records soon, once he gets permission from the researchers involved.

The database could include more than 450 tree-ring and at least 50 sediment based records published in the North American literature, according to database organizers.

The greatest obstacle is just to get people to submit their published data, Swetnam said. "I think 99.9 percent of fire research is funded with public money," he said. "People need to have the ethic that once they have published, they should submit their data so they are really available to the public."

Some prominent scientific journals, including Science and Nature, now require their authors to make their raw data publicly available on the Internet, either on the journals' own sites or on such sites as IMPD.

The challenge for researchers is finding time to submit their data, said Connie Woodhouse of NOAA, a graduate of UA's Tree-Ring Lab and principal investigator for the database project. "We're trying to tackle that in as many ways as we can," Woodhouse said.

Database organizers say they will develop the database to be more useful to forest and land managers by connecting the paleodata to modern data. For example, in the future, U.S. Forest Service managers could have Web access to maps of past fires as well as modern ones.

Swetnam and others have found complex interactions between fire and climate. They would like to add as much data as possible to IMPD as they tease out the effects of climate and climate change from that of fuel build-up.

Like the fire-history scientists who study charcoal layers in lake sediments, the tree-ring scientists found that more frequent fires relate to drought. They also found that wetter-than-usual conditions build up lush growth that fuels big fires a couple of years later. And they also found how fire suppression during the last century limited the surface fires that consumed small trees and logs in U.S. forests.

"We may be seeing the fuel dam bursting," Swetnam said. "We had other dry years during the 20th century, but we haven't had fires this big. The 2002 fire season broke all records."

He added, "There may be increasing signs that what we're seeing is really climate driven. That debate is really warming up. But it's too early to say whether the warming is causing regional fire changes."

Swetnam likened the development of the paleofire database to that of the International Tree-Ring Data Base. The ITRDB was set up, also on a NOAA Web site, following a 1974 meeting in Tucson that set the tone for tree-ring research on climate for decades to come. It has been extremely successful in linking tree-ring scientists at institutions around the world in research. The same could be done for fire history through the paleofire database, he said.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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