Banned in 3 states, Conocarpus thrives in Neelankarai

CHENNAI: With the invasive alien species Conocarpus trees planted in Neelankarai beach to create greenery, the State Forest Department has decided to study the implications of the species whose pollen is hazardous to the human respiratory system. Gujarat, Telangana and Andhra Pradesh have already banned the planting of Conocarpus, which is native to African coasts.

The department's decision follows a representation by O Unnikrishnan, a social worker. "The invasive alien Conocarpus pollinates twice a year and is injurious to human health according to health workers, who confirmed that the pollen grains from the Conocarpus cause a rise in the cases of cough, cold, asthma and other respiratory disorders," the representation handed over to department secretary P Senthilkumar said.

Unnikrishnan told DT Next that he was surprised to find a large number of Conocarpus planted on Neelankarai beach. "This will certainly cause environmental and health hazards. Moreover, the plant is inedible to herbivores. Gujarat, Telangana and Andhra Pradesh have banned the plant in forest, and non-forest areas as well as nurseries. The Tamil Nadu government should also implement a comprehensive ban on the planting of Conocarpus," he urged.

Apart from causing illness, Conocarpus is a water-guzzler and causes depletion of groundwater. "This can be disastrous for a city like Chennai where there is a scarcity of drinking water. In Vadodara in Gujarat, 24,000 Conocarpus trees were planted in 2017-18 and this resulted in the reduction of 1 lakh litres of water per day from the groundwater reserves," Unnikrishnan pointed out.

However, the local bodies tend to plant the trees for its fast growth rate and low maintenance. In a circular issued to ban the tree, the Gujarat forest department highlighted the detrimental impact of its roots on telecommunication cables, drains and freshwater pipelines, as the roots can go deep up to 50 metres.

The forest department's list of 196 invasive alien species in 'Tamil Nadu Policy on Invasive Alien Plant Species and Ecological Restoration of Habitats' has no mention of Conocarpus. However, it acknowledges that Tamil Nadu has 2,459 alien plant species, "most of which are likely to be casual aliens or naturalised species".

When asked, department secretary P Senthilkumar told DT Next that the PCCF has been asked to conduct a scientific study on Conocarpus trees. "It has been highlighted that the trees would cause health hazards. Based on the scientific report, further action will be taken," he added.