World’s highest plants discovered growing 6km above sea level

Suited to scaling peaks

Jim Dolezal

By Aisling Irwin

Vascular plants have set a new record: they have been found growing at a height of 6150 metres above sea level.

Six species of cushion plants have been discovered clinging to a gravelly south-west-facing patch no bigger than a football pitch on Mount Shukule II in the Ladakh region of India.

This sets a record for vascular plants, whereas algae and mosses can grow even higher because they are more tolerant to drought and frost.

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A team led by Jiri Dolezal, of the Institute of Botany at the Czech Academy of Sciences in Průhonice, endured nausea and extreme fatigue studying how plants respond to warming in a location five days’ journey away from the nearest road.

“We could manage only a couple of hours of work a day,” says Roey Angel, a team member from the University of Vienna in Austria.

Jiri Dolezal

But the plants they found were in much better shape, having features that enable them to counteract the long, bitter winters and lack of water. Each was no bigger than a coin, contained a high-sugar antifreeze, and had leaves arranged as rosettes that help them to enfold warmer air.

Their roots were tiny too, but Dolezal was able to make out 20 growth rings in a 1-millimetre root. This implied that one of the plants had been there for two decades, although the others had only been there for a few years.

Climate-driven ascent

Climate change is warming the Himalayas, and these plants are likely to have come from seeds that blew onto land from which a glacier had retreated.

Dolezal says that the average temperature in the short growing season at this spot has risen by around 6 °C in a decade – and he believes that plants will ascend even higher in future.

The crucial factor that limits plant altitude is that they need at least 40 days of frost-free soil each year in which to grow, something that is now probably happening on these and other peaks in the region.

“In the arid Himalayas – mostly Tibet – there are many mountains with vast unglaciated areas available,” says Dolezal. And with longer frost-free periods, this means plenty of new habitat to conquer.

“I’m surprised at the elevation – it’s very high,” says Jan Salick, senior curator at Missouri Botanical Garden in St Louis. But she is encouraged that plants may be able to move to higher altitudes than previously thought, and keep up with climate change.

As part of the GLORIA-Himalaya project, she has found alpine plants in Tibetan China moving upwards at 0.06 metres a year, while the temperature band they usually occupy is outpacing them by ascending at 6 metres a year. The fear is that the temperature increase is encouraging the tree line to ascend too, squeezing the alpine plants out.

This discovery by Dolezal’s team confirms that it’s possible for plants to move upwards more quickly, says Salick.

Journal reference: Microbial Ecology, DOI: 10.1007/s00248-016-0779-8

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