Monsoon study

Published : Aug 25, 2006 00:00 IST

THE Department of Ecology of the French Institute of Pondicherry is collaborating with the National Remote-Sensing Agency (NRSA), Hyderabad, and the Indian Space Research Organisation (ISRO) in reconstructing the vegetational history of the Eastern Ghats and in determining whether there has been any change in the climate/monsoon intensity over the past several hundred years in South India. Although the basic material used in these two projects is pollen grains, multi-proxies such as geo-chemistry and luminescent dating are also used. The Geosphere Biosphere Programme of ISRO is funding the projects.

According to Anupama Krishnamurthy, Researcher, Department of Ecology, IFP, pollen grains from flowers are proxy markers of past vegetation. The outer wall of the pollen grains, which are resistant to the natural process of decomposition, remain the same regardless of time. The pollens remain buried in soil sediments for millions of years. "This pollen-vegetation relationship is one of the first steps in reconstructing past climate," she said.

The IFP's collaborative project with the NRSA focussed on the Eastern Ghats. Researchers collected soil samples from rain-fed natural tanks with a build-up of sediments in the present-day forests in the Eastern Ghats and extracted pollen grains from them.

The aim of the second project, jointly conducted with ISRO, is to find out the dynamics of the monsoons - whether there has been any change in their intensity in the past 1,000 to 2,000 years in South India. Attention is being paid to three sites: those predominantly affected by the south-west monsoon; those affected only by the north-east monsoon; and areas affected by both monsoons. Pollen grains from the soil samples in Parambu Kanmai tank-bed site, near Madurai in Tamil Nadu, would be tested to find out whether changes have occurred in the present-day north-east monsoon and if yes, how much of these changes occurred naturally and how much took place owing to human interference.

T.S. Subramanian
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