BANGALORE: Climate change and global warming may cause plant migration and induce several other changes in plants, scientists have said. Affected plants may ‘sweat’ less, grow fewer leaves and show changes in budding and fruiting time, they have observed.
B R Ramesh, Director of Research at the French Institute of Pondicherry, and his team have studied the distribution of native species in Western Ghats based on bio-climatic variables like rain, temperature and length of dry season and found that certain species from Sri Lanka have migrated to the Western Ghats over the years.
Another scientist studying the impact of such environmental change is Dr Jagdish Krishnaswamy.
He found that in the Eastern Himalayas, trees put forth less leaves in the most productive time of the year and their rate of photosynthesis has slowed over time.
Krishnaswamy works with the Suri Sehgal Centre for Biodiversity and Conservation, Manipal University and Ashoka Trust for Research in Ecology and Environment in Bangalore.
He said trees can have two strategies to cope with moisture stress: they can keep open the stomata -- the tiny openings on their leaves and stems -- for photosynthesis and transpiration (sweating), which can lead to their death. Or, they can shut down the stomata in the dry season, causing carbon starvation which results in fewer leaves, a process called browning.
Earlier this year, Dr Krishnaswamy and two other scientists wrote a paper which stated that trees in tropical mountains, including parts of the Himalayas, could be under moisture stress due to warming.
The paper, ‘Vegetation dynamics in tropical mountains’, was published in Global Change Biology. The other authors of the study were Robert John of the Department of Biological Sciences, Indian Institute of Science Education and Research, Kolkata and Shijo Joseph of the Centre for International Forestry Research, Indonesia.
According to Krishnaswamy, warming can also change the time of budding, flowering and other responses in mountain areas.
“In tropical lowland areas, temperature-induced moisture stress can lead to mortality of shrubs and trees,” he said.
Climate modelling studies dating back to 1998, by Dr Sukumar and Dr N H Ravindranath from the Centre for Ecological Sciences, IISc, suggest that human-induced stresses such as grazing, forest fragmentation and demand on forest produce affect forest response to climate change.
Dr R Ganesan of Suri Sehgal Centre for Biodiversity and Conservation and Ashoka Trust for Research in Ecology and the Environment said trees are a good indicator of climate change. ENS