The BMC finally got going with its tree census to quantify the green cover in the city yesterday. Five teams of five members each set out to record information about trees. The survey, which began with Oval Maidan yesterday, is being conducted using devices enabled with the global positioning system (GPS) technology.

These enable surveyors to record latitude and longitude of a tree, thereby determining its position. They will also feed in information about each tree based on a number of other parameters (see box for details). The contract, worth Rs 2.07 crore, has been awarded to Sar IT Services, a firm based out of Nagpur. The company has been given 12 months to complete the survey.

While the GPS-enabled devices allow for capturing a variety of information, the system has no particular way to account whether a tree has already been counted or not. “There is no system to verify if a lane or a few trees have been missed out from the census,” said Sunish Subramanian, founder of Plants and Animals Welfare Society (PAWS), an NGO.

'Won't mark trees'
In the previous survey conducted in 2008, census takers made marks on trees to indicate that it had been counted. “We’re not using the earlier system. There will be no markings on trees to show that it has been counted. All data will be uploaded on BMC’s website after completion,” said SVR Srinivas, additional municipal commissioner, who is in charge of the garden department.

He added that despite having no physical markings, the system would allot a unique number to each tree. “This number will help us identify if a tree has been cut,” explained Srinivas. Yet another problem in the system is, there is no method to record the age and height of trees. “We will have to take approximate numbers in these cases, as the GPS device cannot calculate it,” said an employee of Sar.