TOI: The BMC tree census says mumbai’s green population has doubled: July 17, 2008

Even when the census was being conducted, environmentalists in the Tree Authority were sceptical about the parameters for classification of trees; most of them felt those parameters were being relaxed to inflate the total. Well, their fears have just come true. The BMC’s tree census booklet is out and it says Mumbai has more than 19.17 lakh trees; but the figure includes 33,202 dead trees and 1.59 lakh subabhul trees, a foreign species known to be weeds and invaders.

“Subabhul trees were brought in by the British because of their ornamental value. They are classified as invaders because they interfere with the growth of other trees. They are found around drains in Mumbai and they are known to block nullahs causing drainage problems. To include these in the census is unjustified because they harm existing trees and may even result in stunting their natural growth,’’ horticulturalist U N Singh, head of the Mumbai Nurseryman’s Association and a Tree Authority nominated member, said.

The tree census booklet says a tree is “a plant that has a woody stem or trunk and has a minimum girth of four inches at a height of 4 feet above the ground level’’. The 1998 census said a tree had to have a minimum girth of six inches to be counted. “More than 5 lakh trees must have slipped in because of the relaxed norms. Most of them probably won’t even survive till the next census,’’ another nominated member, Nilesh Baxi, said. 

The BMC also says a tree should have a “woody stem or trunk and should have a 10-cm (four-inch) perimeter at the chest level of an average-height person’’ but does not mention a canopy or leaves. “So someone could have poured acid at the roots of a tree and it could be still standing with no leaves and dead branches. This tree would be included in the census.

Dead trees can stand for more than 25 years. It doesn’t make sense and defeats the purpose of carrying out the census because they don’t contribute to the ecology,’’ Baxi said. The 1998 census said Mumbai had around 9.5 lakh, experts said, adding that the genuine increase in tree count could be around 6 lakh. “The agency, which counted trees, did it was asked to. It agreed that the new rules did not make sense,’’ Baxi added. 

But BMC officials said dead trees were counted to put things in perspective. “It is important to know how many trees are there and how many are dead. Each census should be rounded and should have all sides of a story. Dead trees, too, have a role to play in ecology, they are home to several species and insects. That’s why the government has taken a decision to keep the dead trees in forests also,’’ an official from the gardens and zoo department said.

Experts like botanist M R Almeida, however, disagree. “A dead tree becomes dysfunctional in terms of acting as a pollution-preventer. Dead trees should not have been counted,’’ he added.

DEAD WOOD

   33,202 dead trees have been counted and included in the green population.

Andheri-E with 2,837 dead trees and Bhandup (2,619 dead trees) make up about a sixth of the dead-wood population.

People who participated in the tree census said they were asked to include dead trees to shore up numbers.

THE PARAMETERS

    The BMC’s Tree Census-2008 booklet says only plants having a minimum girth of 4 inches at a height of 4 feet above the ground level can be considered to be trees.

The plant should also have a woody stem or trunk.

“It was mutually decided to restrict (the census) to the trees having woody stem or trunk and having minimum 10-cm (4-inch) perimeter at the chest level of an average-height person,” the booklet says. 

The booklet also says that a tree is a perennial, woody plant capable of attaining a height of at least 4 metres, with a single woody, self-supporting trunk or stem that is usually unbranched till some distance above ground.

THE GOOD AND THE BAD

S Ward (Bhandup) is Mumbai’s greenest ward with more than 1.59 lakh trees; K-East (Andheri-E) is a close second with 1.56 lakh-plus trees and RCentral (Borivli-E) comes third with more than 1.44 lakh trees.

C Ward (Chandanwadi) is the worst in terms of green cover with only 3,919 trees; neighbouring B Ward (Mohammad Ali Road) does not fare much better with 6,786 trees. These are the only two wards in Mumbai that have less than 10,000 trees.