Antarctic plants may face a growing fungal threat from warming soils

Global warming will expand the tiny Antarctic plant community. But it could also foster pathogenic fungi in soils that might kill those plants.

Analyses of soil samples from southern Chile to the Antarctic Peninsula reveal that fungi that prey on plants grow more abundant and diverse with higher air temperature, researchers report in the May Global Change Biology. By 2100, the team says, projected warming could double the occurrence of those fungi in some coastal Antarctic soils.

Less than 1 percent of Antarctica’s land is ice-free. Even the relatively wet, mild Antarctic Peninsula and nearby islands are forbidding to plant life, which can spend up to eight months covered in snow. But some cold-adapted plants, such as mosses and liverworts, cling to life. 

There’s often an assumption that as Antarctica’s ice recedes due to warming temperatures, the continent’s plants will happily colonize the newly available land, says Kevin Newsham, a soil and plant ecologist with the British Antarctic Survey, based in Cambridge, England. But “in reality, it won’t be like this. The plants aren’t going to have it strictly easy.”

Fungi that cause plant disease lurk in soils worldwide, though little has been known about the threat they pose to Antarctica’s plants. So Newsham and his colleagues collected and analyzed fungal DNA in over 50 samples of soils along a 1,900-kilometer swath through southern Chile, Antarctic islands and the Antarctic Peninsula.

The researchers also analyzed how each site’s climate correlated to fungal abundance and diversity. What they found was startlingly simple: The warmer the climate, the more pathogenic fungi were present, in both number and variety. Under medium high to high future greenhouse gas emissions scenarios, those numbers could double by the end of the century.

The southernmost soils the team analyzed, on islands along the Antarctic Peninsula, had relatively few pathogenic fungi. Doubling, therefore, might not mean a huge jump in absolute numbers. But even one new species of fungus could devastate Antarctica’s unprepared plant life, Newsham says. “A single species of pathogens, introduced to an environment where plants don’t see pathogens often, can have disproportionately large effects.”

Such effects have hit temperate plant communities before, from chestnut blight in North America to Dutch elm disease in Europe to root-infecting pathogens decimating Eucalyptus forests in Australia.