Bring me the Head of Medusa
Consider This: In Greek mythology, Medusa was a mortal woman transformed into a dragon-like creature with snakes for hair. And if you gazed upon her foul visage, she would turn you to stone - for eternity.
story & photos by Susan Carter
After the mythological powers of medusa are invoked, it's no surprise that a noxious, invasive weed whose common name is Medusahead would be deemed a very undesirable usurper in the Pacific Northwest.
But Here's the Rub: Medusahead was actually introduced into the U.S. from Eurasia way back in the late 1800s. And after over 100 years of infestation, this weed now occupies millions of acres of semi-arid rangelands in the Pacific Northwest where it can be found in virtually every county in Oregon. It's especially prevalent in eastern Oregon, sucking up scarce spring moisture before perennial grasses get a chance to grow. And because Medusahead is loaded with silica, it's unpalatable as grazing food for cattle or sheep.
Once this weed becomes established in a local ecosystem, the land becomes nearly worthless, incapable of supporting native wildlife or livestock. In fact, the eyes and mouths of grazing animals can even be injured by the Medusahead's sharp and hairy bristles. This dangerous species even changes the temperature and moisture content of the soil in which it grows, greatly reducing successful seed germination for other more desirable grass species - and thus increasing the likelihood of fostering damaging wildfires.
Clash of the Titans
Taeniatherum Caput-Medusae, also known as Medusahead, became well established on 6,500 acres of the BLM's North Bank Habitat Management Area. Originally acquired by the Roseburg District through a land exchange in 1994, this area was acquired in order to secure a safe habitat for the Columbian whitetailed deer, a species listed as endangered at that time.
Once this habitat was acquired, the North Bank Habitat Management Plan was developed in cooperation with the U.S. Fish and Wildlife Service and the Oregon Department of Fish and Wildlife. After they were designated an Area of Critical Environmental Concern, these acres saw the Columbian white-tailed deer subsequently removed from the federally endangered species list by 2003.
But in recent years, the ongoing plan to manage the North Bank Ranch acres for a healthy ecological balance has required botanists and prescribed fire managers to collaboratively reverse the increasing march of the Medusahead. So land experts developed a plan to fight fire with fire! They'd burn the weed in the spring when the Medusahead seed was in the "milky" or "doughy" stage and before any seed dropped to the ground. The idea was to prevent the seeds from becoming viable and consequently reduce the reproductive capability and the future recruitment and expansion of Medusahead on the North Bank Ranch.
Prometheus the Fire-Bringer
They started small with a 34-acre prescribed burn in the spring of 2007. Monitoring conducted the following summer noted a remarkable decrease in Medusahead - from about 90% frequency to 17% frequency. With this encouraging statistic, resource specialists were eager to burn additional Medusahead-infested areas. In 2008, approximately 40 new acres were burned. And in 2009 botanists noticed that Medusahead was increasing on the original 34 acre burn area and recommended that the area be treated again along with adjacent acres. This time, a total of 70 acres were burned. But the good news was that vegetation monitoring conducted just days prior to the burn showed a frequency of 38 percent Medusahead - still substantially lower than the 90 percent that was present before this effort began in 2007. It is likely that it will take continued effort to combat this formidable foe.
And as Medusa's power is defeated, the BLM has conducted reseeding efforts in these burned areas to re-establish more desirable native species of forbs and grasses that better support the Columbian whitetailed deer and other native wildlife.
Initial post-fire monitoring at the North Bank Ranch looks promising this year. Most of the Medusahead either burned or lay down. The passage of time and future monitoring will tell a more detailed story, but for now, instead of turning to stone when they looked at Medusahead, BLM resource specialists drew themselves up and accepted the daunting challenge of controlling this aggressive weed species - and have dealt a serious blow to this noxious invader of public lands.
Learn more about the use of prescribed burning on public lands.