Annual bluegrass (above), the same weed that plagues gardens and golf courses around the world, is one of hundreds of alien species now invading Antarctica.
The icy continent’s only two native grasses have experienced a growth spurt as temperatures rise and ice melts, and biologists worry that the same conditions will facilitate an alien invasion that will threaten native ecosystems.
In a new effort to stem the onslaught, a team of biologists assessed the likelihood that these foreign species would take up residence on the icy continent, both now and by the year 2100, when the climate will likely be considerably warmer.
In a study published today in the Proceedings of the National Academy of Sciences, they mapped “hot spots” where invasive plants are most likely to take root (warm colors in the map below):
Despite “Don’t Pack a Pest” campaigns and plenty of good intentions, tourists and scientists carry thousands of seeds and other detachable plant parts to the southern continent each year in Velcro hems, knit caps and dirty bootlaces.
For the new continent-wide assessment, Steven L. Chown of Stellenbosch University in Matieland, South Africa, and his colleagues sampled, identified, and mapped the sources and destinations of more than 2,600 plant parts that hitched a ride to Antarctica during 2007 and 2008. They found that each visitor transported fewer than 10 seeds on average, but the 30,000-plus Antarctic visitors per year were sufficient for invasive species to establish themselves on the Western Antarctic Peninsula (largest red zone in the map above).
Annual bluegrass is one of the true pioneers among them. This plant has been taking root near research stations for at least 25 years, but last year Polish biologists reported its intrepid spread into non-disturbed areas, some 1.5 kilometers from the nearest research station on the moraines of a retreating glacier on King George Island.
Sounds like Antarctica may indeed be the next market for lawn mowers.
Annual bluegrass (Poa annua) has colonized nearly every sub-Antarctic island. Courtesy of Wikimedia Commons.
Increase in annual cumulative degree days, indicating increasing risk of alien species establishment. Courtesy of PNAS and Steven L. Chown.