‘Stress factor' of trees to calculate risk to road-users

For the next five months, every Saturday, about 5,000 students from various schools and colleges will be seen measuring trees on the streets of the city. The students are part of an exercise to develop a census of the tree population in Greater Chennai, which extends from Tambaram to Avadi.

The students will be guided by Botany professors and post-graduates from Women's Christian College, Madras Christian College and the Presidency College. The National Green Corps volunteers are also part of the activity. Armed with a guide book prepared by the Forest Department, the students will fan out in batches of five across the city and measure the girth and height of each tree.

Studying tree cover

According to D. Narasimhan, Botany professor, MCC, “The girth and height of a tree will help calculate the biomass, which will indicate how much carbon a tree absorbs. It will help us understand if there is enough tree cover in the city to absorb the carbon emissions and find ways to increase green cover in areas where it is less.”

The enumerators will jot down the details in a form which also includes a column called ‘stress factor.' This includes suggestions to remove trees that lean dangerously on the road or “weak stemmed” trees which could fall during monsoon.

A tree that leans on to the road could injure pedestrians or motorists and must be removed, he said. “We will use the guidelines provided by the Forest Department to advise non-governmental organisations on the species that can be planted. We have identified 50 native trees that are fit for plantation along avenues in the city,” Dr. Narasimhan added.

The students will also collect flowers/leaves of rare species which would then be identified by experts. The data on heritage trees could be used to conserve them, the expert said.

While the International Union for Conservation of Nature has mentioned that some rare species of trees are found in Chennai, no data is available with the Forest Department, Dr. Narasimhan said. The census would help prepare a directory of rare/endangered tree species, including those grown in private homes.

Principal Chief Conservator of Forests Gautam Dey said identifying rare species would help to propagate them. “We will try to work with the government and offer incentives to the owner of rare species of trees to help grow them,” he added.

The Urban Forestry Division of the Forest Department has allotted Rs.10 lakh for conducting the census, Forests Minister K.T. Pachamal, said at the launch of the census on Wednesday at the Guindy National Park here.

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R. SujathaJune 28, 2012