Have you ever looked for an eye-opening example of how an invasive species can have serious negative impacts? One of the best examples here is Oregon is the story of how an invasive weed caused the Bandon fire.
The account below comes from the Oregon History Project website: http://www.ohs.org/education/oregonhistory/historical_records/dspDocument.cfm?doc_ID=9326D333-960F-57C1-C7CB9A48D590224F
Upon his arrival in Oregon in June 1873, Irish immigrant George Bennett (1827-1900) and a handful of other colonists decided to establish a new community at the mouth of the Coquille River. “We thought it was just the very place for a town,” he later recalled, “and that it was only a question of time when there would be a very thriving one there.” Bennett named the future community after his home town Bandon, located in County Cork, Ireland.
Bennett brought with him an ornamental shrub (Ulex europaeus)—known variously as gorse, Irish furze, and Irish hedge—that soon became a common sight in the new town. Remembering his childhood visits to Bandon in the early 1930s, historian Thomas McClintock wrote that gorse filled the spaces between the town’s scattered buildings. “During one of our vacations in Bandon,” he wrote, “a fire started in the gorse which was rather frightening because of the intense heat and flames which rose a hundred feet into the air. Fortunately, on that occasion the fire was eventually brought under control with no loss of property.”
The residents of Bandon would not be so lucky on September 26, 1936. On that late summer day a forest fire burned several miles east of town, far enough away that the residents of Bandon were not particularly worried. A sudden shift in the wind, however, drove the flames swiftly westward. Ignited by the forest fire, the town’s abundant gorse exploded into an inferno. Bandon resident D.H. Woomer told a Coos Bay Times reporter shortly after the fire: “That Irish hedge was the worst thing—when the fire hit it right across from my house, the flames shot up high into the air. It was just as though there had been gasoline poured on the fire. And water was just no good against it—wouldn’t touch it! The stuff seemed just full of oil.” Ironically, just a week before the fire Frank P. McWhorter, the state plant pathologist, had warned Bandon’s residents of the fire hazards posed by the gorse.
The fire quickly swept through the town, laying waste to the business district along with hundreds of homes. Only a handful of structures were left standing by the time the fire died out. Most of the town’s 1,800 residents managed to reach safety, though ten died in the flames.
Gorse was considered a desirable ornamental plant when Mr. Bennett brought to Oregon. I’m sure he had no idea it would become a noxious weed and, because of it’s high oil content, a fire hazard. It wasn’t until 19__ that gorse was listed as a noxious weed in Oregon and it was still legal to import, propagate, and sell gorse in this State until 1999!
Today Gorse is officially a B-rated weed, meaning that it is too common to eradicate completely from the State, but it is still desirable to keep it from spreading to new areas. ODA has drawn a “line in the dunes” at Florence. Infestations north of that line and inland from the crest of the coastal mountains are suppressed. South of the line, gorse management is up to landowners.
A few years back ODA released a biological control agent in the generally infested area that briefly seemed to have promise. It was a spider mite that fed only on gorse. At first populations built up and spider mite webbing was all over the gorse at the release sites. We were concerned that residents might find the webbing unsightly. From a distance it looked like plastic bags had be draped over the branch tips! No one ever complained though because the gorse spider mite populations soon crashed after a non-native, but commercially sold, predator mite moved in and wiped them out.
Interestingly, gorse in it’s native habitat doesn’t look as good or grow as robustly as it does in southwestern Oregon. I’ve seen it in northern France; you wouldn’t recognize gorse there as the same plant. Natural enemies must be keeping it from growing into huge thickets like it does here. Hopefully, someday scientists will find gorse-specific biological control agents that we can safely introduce. In the meantime, we all need to be careful bringing in favorite plants from far away places. There is no doubt in my mind there are bad actor plants for sale today in Oregon that will haunt our grandchildren. Scientists are just beginning to develop tools to predict invasiveness and nurseries and plant quarantine officials have yet to begin using them.
Let’s hope we don’t have another incident like the Bandon fire to remind us how serious invasive species can be. Of course, there is cheatgrass, another fire-adapted species that is spreading like wildfire and stoking wildfires all over the West, but that is a story for another blog.
April 5, 2010