History of worldwide wildfires is studied

EUGENE, Ore., Sept. 25 (UPI) -- U.S. and European scientists say there was a dramatic decline in wildfires from 1870 to 1970, following a period of increased fires between 1750 and 1870.

Led by Jennifer Marlon, a University of Oregon doctoral student, nine researchers from seven institutions in France, Switzerland, the United Kingdom and the United States analyzed 406 sedimentary charcoal records from lake beds on six continents.

The scientists discovered that from 1 A.D. to 1750, the number of wildfires worldwide declined from earlier years. The researchers said the widespread expansion of intensive agriculture, grazing and forest management efforts probably contributed to the reduction.

The increase in wildfires between 1750 and 1870 was likely due to several factors, said Marlon. "Population growth and European colonization caused massive changes in land cover, and human-induced increases in atmospheric carbon dioxide concentrations may have started to increase biomass levels and fuels."

The researchers said worldwide wildfires again declined from 1870 to 1970, despite increasing temperatures and population growth. That decline, said Marlon, "can be attributed to a global expansion of agriculture and intensive grazing of livestock that reduced fuels, plus general landscape fragmentation and fire-management efforts."

The study appears online in the journal Nature Geoscience.