The tsunami of 2005 virtually devastated the shores of Kollam district in Kerala but strangely, a small piece of coastline along this place called Vallikkavu was spared. And the plantation of five-metre tall casuarina trees, nurtured by an ashram in the area — three years ago — was believed to be the reason why the coast was protected by the surging sea. The ashram had discovered the potential of the tree while helping preserve the coastline of Valappad, which was constantly facing the threat of sea erosion.
They discussed the tree with the local elders and they readily agreed, for they had been watching helplessly for decades the sight of vast expanses of beach giving in to the marauding waves — a government-constructed seawall offering no respite. The ashram went ahead with the project and the shores now have escaped the threat of rising tides. Now, the Alappuzha district administration is planning to plant causarinas on its 82-km long coastline.
But how is a tree able to hold off the sea? “Casuarina is a nitrogen-fixing salt-resistant plant that can survive on salty soil thanks to frankia — the nitrogen-fixing bacteria, found in its roots,” says Dr Shalini Ojha, a research fellow at the Department of Botany, M.S. University of Baroda. “They grow in poor and nitrogen-deficient soils thanks to the symbiotic relationship with Frankia actinomycetes that help in the growth of plant. The litterfall (dead plant material that falls on the ground) quantity is another factor that helps maintain reasonable moisture levels around the plantation. They can even control air pollution.”
Dr Ojha is currently undertaking a study to develop a protocol for extensive plantation of the casuarina using frankia and bio-inoculants. The Kerala Forest Research Institute is also backing causarinas plantations along the coasts. Dr P. Sujanapal, a scientist with KFRI, says the sand-holding capacity of the plant is very high, for its roots act like a mesh beneath the soil. “It checks wind velocity and reduces damage during the calamity. It is also able to improve environmentally-degraded soils. Casuarinas are now replacing the local plants which had been grown in the less–fertile shores.
The plant is fast-growing and is easily-available. It’s not just a geographical boon. Clumps of casuarinas also offer a means of livelihood for people along coastlines. The trunk of the tree is the best form of firewood and can be used in the making of charcoal. The wood can be utilised for making paper and hardboards. Casuarina also possesses medicinal properties — the bark of the tree is used in the treatment of diarrhoea and dysentery.
