Coimbatore

Delay in onset of ground frost points to climate change: ecologists

The ground frost in Udhagamandalam in January last year.

The ground frost in Udhagamandalam in January last year.   | Photo Credit: M_Sathyamoorthy

‘It may provide an opportunity for invasive flora to spread into native grasslands’

The unprecedented delay in the onset of ground frost in the Nilgiris this year could have an impact on local ecology by providing an advantage to invasive species of flora and help them spread into native grasslands, ecologists warn.

Ground frost, which usually sets in by the middle of December each year, leads to most places in the upper Nilgiris, from Mukurthi National Park to Udhagamandalam and parts of Coonoor and Kotagiri becoming carpeted with a layer of ground frost each morning for up to two months at a time.

The ground frost, which sets in during December extends well into January and leads to the gradual drying up of flora, which then leads to a cycle of regeneration a few months later, providing fresh reserves of ground fodder for ungulates in the Nilgiris.

K. Kannan, Principal Scientist and head of the Udhagamandalam station of the Indian Institute of Soil and Water Conservation (ICAR-IISWC), said that based on records compared since 1968, the dew gauge has measured the intensity of ground frost on an average as being around 4-6 during December and 6-8 during January.

“However, the scale has been at three on an average even in January this year,” said Dr. Kannan, adding that visible ground frost covering large parts of the Nilgiris has not been recorded this winter as yet.

He added that the lack of ground frost could have an impact on fruiting trees. “The process of vernalization, or exposure of a plant or tree to prolonged winter coldness induces flowering and eventual fruiting,” said Dr. Kannan, who added that such a cycle might be disrupted due to the delay in the onset of ground frost this year.

There are also concerns among conservationists that the lack of ground frost could provide an opportunity for invasive flora to spread into native grasslands in the Nilgiris.

Godwin Vasanth Bosco, a restoration ecologist based in the district, said that ground frost acts as a control to prevent the spread of woody plants that would otherwise have an opportunity to take over grasslands.

“Moreover, invasive plants like Eupatorium, Lantana camara and Cestrum will be killed off from any grasslands that they manage to spread into due to the freezing and thawing effect of ground frost. So, the weather itself acts as a natural controller of invasive species,” said Mr. Bosco, who added that climate change could be a factor leading to the delay in the onset of ground frost.

“The fact that we have not seen ground frost in December and January shows that night time air temperatures are not cold enough to force the air to condense and settle on the ground below,” he said.

He added that people needed to take cognizance of the subtle changes in weather and ecology as a warning sign that climate change was having a huge impact across the world, including biodiversity hotspots such as the Western Ghats.

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Printable version | Jul 14, 2020 7:20:15 AM | https://www.thehindu.com/news/cities/Coimbatore/delay-in-onset-of-ground-frost-points-to-climate-change-ecologists/article30497667.ece

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