Natures wonders: plant extremophiles (Introduction)

by David Turell , Sunday, June 11, 2017, 00:04 (2721 days ago) @ David Turell

In volcanic areas at 72 degrees C:

https://www.newscientist.com/article/2134206-extreme-plants-thrive-at-72c-in-new-zealan...

"A survey of plants growing in a highly-active volcanic area in New Zealand, where soil temperatures can reach 98.5°C, has revealed several species of vegetation that can survive the extreme conditions.

"Geothermal fields, areas where the ground is heated up by molten rock below, are known for their hot springs and geysers. But they contain distinct vegetation, too.

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"They sampled vegetation, measured soil temperatures, and analysed soil samples to determine the pH level and metal content, for example.

"Geothermal soil often has extreme pH levels, and unusually high – and sometimes toxic – levels of metals such as aluminium, which are thought to affect plant growth.

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"Plants with shallow roots, for example mosses and liverworts, were the only survivors in zones with extremely hot soil, the temperature of which they measured at 10 centimetres below the surface.

"Smale and his colleagues found that a moss, dwarf swan-neck moss (Campylopus pyriformis), which thrives in a range of climates, was the most heat-tolerant plant in the areas they surveyed. It was found in soil where temperatures reached 72°C.

“'It supports only one species,” says Smale. “Apart from perhaps thermophilic algae, no plants can survive temperatures above about 80°C.”

"Since soil temperatures at such sites rise the deeper one goes, even these heat-tolerant species are restricted to the top few centimetres of the hot soil. They’ve adapted by having short roots – or roots that spread out laterally instead of downwards.

"Subjecting a plant’s roots to high temperatures can increase metabolic activity in cells and reduce growth, so some geothermal grasses have adapted by tweaking their root respiration rates.

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"In areas where the soil was a few degrees cooler, at 68°C, Smale’s team found geothermal kanuka, a shrub endemic to New Zealand, and staghorn clubmoss, Lycopodiella cernua, which is widespread in tropical climates.

"Overall, there were few flowering plants. Soil temperature was found to be the main factor limiting plant growth.

"Todd Rosenstiel from Portland State University, who studied plant communities at geothermal sites in Lassen Volcanic National Park in California, also found that mosses dominated at the highest temperatures. “There seems to be a convergence of plant community structures across geothermal zones,” he says."

Comment: There seem to be few limits to where life cannot go.