In what appears to be another grim outcome of climate change, a study has found that forests in eastern Himalayas are gradually 'browning', with trees withering and foliage declining even during productive seasons. Similar changes were noted in tropical mountain forests across the world.

 

The study covered 47 protected areas across five biodiversity hotspots. It used satellite images from 1982 to 2006, which revealed a common trend: there was mild greening till the mid 1990s and then came a sudden and steady reversal which is making these forests appear drier and brown.

 

This may mean that the trees in these forests are not able to transpire at the optimum level and their photosynthesis activity has reduced due to temperature rise.

 

"One would imagine that the mountains would become more green with the rise in temperature, but it is not so," said Jagdish Krishnaswamy, one of the authors and a scientist at Ashoka Trust for Research in Ecology and Environment ( ATREE).

 

Says Robert John, faculty at the Indian Institute of Science Education and Research and co-author of the study, "It's interesting that all these five regions are distinct climatically. We found that the browning trend is statistically significant. It's real. The trend may not have started at the same time in all the regions though."

 

Among others, the study has covered Mt Kilimanjaro and Rwenzori in Africa; Huascaran and Medidi in South America; Jigme Dorji and Jigme Singye national park in Bhutan in south Asia along with the two other forests in India and Khakaborazi national park in Myanmar; Lorentz national park in Indonesia, southeast Asia.