It is believed that medusahead (Taeniatherum caput-medusae) was first brought to the the western United States in the 1880s with imports of livestock and their bedding. Medusahead is native to Mediterranean and European countries that have climates similar to Southern Oregon and the Intermountain West, which is why it has done so well in the American West.
Medusahead was first found near Roseburg Oregon in the 1880s which is where it began its slow assault on western rangelands. By the 1950s, many properties had been overgrazed and medusahead began to spread much more aggressively into depleted rangelands on the east side of the Cascade Mountains. There it formed vast monocultures and in many areas crowded out the few remaining native plants that were left after overgrazing. It has continued to spread to the north, east, and south in subsequent years.
Medusahead has no virtues and once it has taken hold of the land it is difficult to control-- impossible to get rid of-- on a large scale. It’s presence on over 3 million acres has devalued the land for agricultural production and biodiversity in 17 western states. To make matters worse, medusahead has totally altered how often and how hot wildfires burn on the infested rangelands.
What Gives Medusahead the Advantage Over Native Plants?
Medusahead is a cool-season annual grass that starts growing in the late fall or winter and sets seed in the spring. It can often be found growing with cheatgrass (Bromus tectorum), which is another pesky, introduced annual grass that has a similar life cycle to medusahead. By the time the native plants wake up from their winter slumber, the medusahead and cheatgrass have used most of the nutrients and moisture in the arid soils.
Medusahead doesn’t produce much leaf growth, but instead forms short, dense mats of fine blades that are carpet-like in appearance. It has zero forage value for either wildlife or livestock.
Medusahead is a prolific seeder that can produce up to 6000 seeds per square foot. The seed is high in viability and creates a seed bank that will last about a year. The seed heads have long, bristly awns that are high in silica content. The silica makes litter from the seedheads very slow to decompose, so the litter builds up into thick layers of thatch that don’t allow more desirable plants to establish or compete. The awns on the seedheads enable the seed to hitch a ride in the fur of passing animals, which allows transport to new locations ready for invasion.
Medusahead and Fire
Large scale monocultures of medusahead in parts of the west have increased frequency and intensity of wildfires in those areas. It seems that fire helps medusahead perpetuate itself in the landscape.
The deep and dense litter that builds up when medusahead dominates a site is capable of becoming totally dry and is incredibly flammable. Even after a rain event, it takes the litter only a few hours to dry out and become highly combustible again. The litter is termed as a "fine and flashy fuel" that can carry ground fire many feet per second. Wind can quickly turn the situation explosive and increase danger for firefighters because it increases the rate of spread and causes the fire to spot hundreds of feet ahead of itself.
Research has proven that prolonged heat from a fire can kill much of the medusahead seed and reduce the amount that has potential to grow during the next growing season. However, most of the time there are islands within a burn where the fire wasn’t as hot or didn’t burn at all. Those areas still have viable seed that is ready and able to re-infest the burned area. Erosion after a fire also increases the risk of more medusahead growing back on the site because the plant tends to favor disturbed areas where there has been loss of topsoil. As long as medusahead dominates a site more frequent fires can be expected. It is an endless cycle of continued and increasing degradation.
Methods for reclaiming rangeland from medusahead infestations have been searched for, but so far effective methods remain elusive. On a small scale, some progress has been made by using a mix of timely prescribed burns, herbicides, and mechanical methods. These types of treatments are very expensive though, and for the small amount of improvement that results they haven’t proven to be cost effective.
So for now, the current recommendations for medusahead are to treat the small and encroaching infestations to try and stop the spread. On the land where medusahead has taken a stronghold it’s anyone’s guess what will happen to it in the future, but waste is assured.
References:
Fire Effects Information System. Accessed January 6, 2012.
Helen McGranahan - Helen McGranahan has worked her entire career dedicated to wise and sustainable management of natural resources.
