While many people cozy up next to warm fires in the winter, experts warn that owners of wood-burning fireplaces should take care when choosing wood and buy local.
Firewood transported to different areas has been a key factor in the introduction of nonnative pathogens and insects that can harm ecosystems, said David Wood, professor emeritus of entomology at UC Berkeley.
Among the biggest concerns is that firewood could help spread diseases such as sudden oak death. That disease, which is caused by a pathogen that kills some oak species by attacking the trunks, was first found in Marin County in 1995. It is now found in 14 California counties between Humboldt and Monterey, as well as Curry County, Ore.
Even wood that appears safe can have invasive beetles living under the bark. Those beetles can damage trees on their own and also carry the pathogen that causes sudden oak death, Wood said.
"If the beetles have found a tree, it's not going to live very long," he said. "Sudden oak death is bad enough without having this beetle."
In Marin County, the disease is killing an estimated 25 percent of coast live oak trees. The dead trees increase fire danger and also mean less habitat for wildlife.
Experts say many people aren't aware of the danger of transporting firewood.
For example, some campers may visit different sites on a trip but collect all of their wood at the first campsite. That wood can be introduced to multiple susceptible environments within a short period of time, said Leigh Greenwood, coalition manager for the Nature Conservancy's Forest Health Program.
For two years, campsites at Humboldt Redwood State Park have been under quarantine because of an outbreak of sudden oak death. No wood can be brought into or taken from the park, and any campers wishing to build fires must do so with wood sold inside the park.
"At this point (the disease) is fairly new in our area," said Sandra Bartlett, manager of the visitor center.
Containment is the best hope to prevent new infestations.
That's what Kevin Turner is trying to do in San Diego County, where the gold-spotted oak borer has killed an estimated 22,000 trees in the Cleveland National Forest and surrounding areas.
The insect's DNA resembles that of an isolated species in Arizona, and it is believed it was brought to California in a load of firewood, said Turner, who coordinates the oak borer research program for UC Riverside Extension.
Oak borers can live in wood for up to two years, so Turner tells vendors to keep wood for at least that long before selling it. He also wants the public to watch for signs of infested firewood, such as D-shaped holes where the larvae have bored.
Buying locally produced firewood and being cautious are the best ways to make sure firewood doesn't spread problems, said Susan Frankel, who manages the U.S. Forest Service's sudden oak death research program.
"It is a matter of awareness," she said.
-- Wood found at a campground should stay at the campground.
-- Don't move wood to different locales. It may look pest-free, but may have critters under the bark.
-- Don't transport wood more than 50 miles from its source.
-- If you do move wood more than 50 miles, burn it immediately.
Source: Don't Move Firewood Campaign