Antarctica’s only two native flowering plant species, Antarctic hairgrass and Antarctic pearlwort, have developed contrasting physiological responses to long-term warming, according to a seven-year study conducted on King George Island and published in Physiologia Plantarum.
Seven-Year Field Experiment on King George Island
The research project began in 2012 just north of the Antarctic Peninsula, where scientists established experimental plots surrounded by open-top chambers, or OTCs. These transparent enclosures passively warm internal air by several degrees to simulate future climate conditions. While laboratory simulations often focus strictly on rising mean temperatures, this field study documented ecologically relevant phenomena such as increases in freeze-thaw events over a sustained period. The work was carried out by researchers from the Institute of Ecology and Biodiversity, Universidad de La Frontera, Universidad de Concepción, and the Anillo ATE253400 project, alongside Spanish research institutions including CITA-Aragón, EEAD-CSIC, and the University of the Balearic Islands.
Hairgrass and Pearlwort Show Divergent Survival Tactics
Antarctic hairgrass, known scientifically as Deschampsia antarctica, and Antarctic pearlwort, or Colobanthus quitensis, represent two distinct extremes along an adaptive continuum. After seven years of passive warming, hairgrass reduced both its leaf hydraulic conductivity and its photosynthetic rate. Co-author Patricia Sáez explained that these shifts reflect a conservative water-use strategy that prioritizes stability and hydraulic safety. Conversely, pearlwort displayed the exact opposite pattern. It increased its hydraulic conductivity, photosynthetic capacity, cell-wall elasticity, and the transport of water and carbon dioxide. Sáez stated that pearlwort prioritized plasticity and rapid acclimation, supported by changes in its vascular anatomy and a cushion growth form that helps conserve heat.
Coexistence and Recent Plant Expansion in Antarctica
The physiological divergence helps account for why both species have managed to expand across the continent in recent decades despite regional warming trends. Lohengrin Cavieres, another co-author of the study, noted that the existence of different adaptive strategies explains their shared success in one of the most severe environments on Earth. The distinct reactions indicate that the plants do not compete directly for the same resources, showing how they have successfully coexisted in similar habitats over long periods. A 2017 study previously documented that northern populations of pearlwort had expanded into areas outside the Antarctic continent proper, while colder southern temperatures had limited the spread of southern populations.
Common Questions About Antarctic Vegetation
How many flowering plant species grow natively in Antarctica?
Antarctica is home to only two native vascular plant species: Antarctic hairgrass and Antarctic pearlwort.
Where was the seven-year warming study conducted?
The fieldwork took place on King George Island, situated just north of the Antarctic Peninsula near the Polish Antarctic Station Henryk Arctowski, using open-top chambers established in 2012.
How do the two plants differ in their response to rising temperatures?
Antarctic hairgrass adopts a conservative water-use strategy by reducing its leaf hydraulic conductivity and photosynthetic rate to prioritize stability, whereas Antarctic pearlwort increases its hydraulic conductivity, photosynthetic capacity, and cell-wall elasticity to prioritize plasticity and heat conservation.
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