The Telegraph
Tuesday , October 22 , 2013

Tropical mountains lose green cover

- ‘Browning’ blamed on warming

New Delhi, Oct. 21: High-altitude parks across Asia, Africa and Latin America have steadily lost foliage over the past 15 years, according to Indian ecologists who say such changes may also be happening at mountaintop getaways popular among tourists worldwide.

A team of ecologists at the Indian Institute of Science Education and Research in Calcutta, the Ashoka Trust for Research in Ecology and Environment in Bangalore, and an Indonesian institute has observed a steady “browning” of tropical mountain regions since the late 1990s.

“The trend is sharp and clear, and we saw it in every region where we looked,” Robert John Chandran, assistant professor at the Calcutta institute and a team member, told The Telegraph. “Tropical mountain regions appear to be losing their leaf cover.”

The researchers, who used satellite imagery from 1986 onwards to analyse vegetation changes in 47 high-altitude parks or sanctuaries, observed the highest rates of foliage loss in Central America and significant losses in South Asia, Africa and South America. Their findings were published this month in the journal Global Change Biology.

The ecologists examined protected zones in the Himalayas, the highlands of Ethiopia and Kenya, the Andes and in Central American mountains. But, Chandran said, similar effects may also be expected to be occurring in the mountain regions popular among tourists.

“Human activity in unprotected zones is only likely to exacerbate such effects,” he said.

The study revealed that tropical mountain foliage had increased in all the continental regions until the mid-1990s. Since then, all the regions have been displaying what the scientists have described as “stronger browning”.

Chandran and his co-authors, Jagdish Krishnaswamy from Ashoka Trust and Shijo Joseph from the Centre for International Forestry Research in Indonesia, suspect that moisture-stress because of increasing temperatures may help explain the foliage loss.

The scientists cite how regional climate studies have shown that average land temperatures have risen by about one degree Celsius in Africa, Central America and South Asia over the past two decades.

“It’s possible that tropical mountain regions respond much faster to temperature changes than other regions,” Chandran said. “And the changes in foliage and moisture may have other impacts on the local flora and fauna.”

Seven years ago, scientists in Costa Rica, a nation sandwiched between the Atlantic and Pacific Oceans, blamed rising temperatures and large-scale ocean warming for the mass extinction of amphibian populations in the tropical American region.

J. Alan Young at the Monteverde Cloud Forest Preserve and Tropical Science Centre in Costa Rica and his colleagues had reported in the journal Nature that the mass extinction was tied to outbreaks of a disease-causing fungus.

The scientists said the temperature rise had led to a fall in the amount of mist in the Costa Rica mountains, which promoted the growth of the fungus that had annihilated amphibians in the region, including the Monteverde harlequin frog and the golden toad.

“We need to understand what the foliage changes we have observed might mean for plants, animals or birds in the other tropical mountain regions,” Chandran said. Such an effort would require years of ground observations.