CHENNAI: Construction of metro phase-2 will begin later this year to make commuting to suburbs easier, but it will come at the cost of the city’s green cover. As many as 2,034 trees are set to be axed for the 118.9km three-corridor network. To make up for the loss, the Chennai Metro Rail (CMRL) will spend more than Rs3.8crore to plant saplings.Nearly 55% of the trees will be felled in corridor-5, the largest of the three lines planned over 47km, linking Madhvaram to Sholinganallur via CMBT. It will link several localities on the western fringes of the city including Retteri, Kolathur, Adambakkam, Madipakkam, Kovilambakkam and Medavakkam. Two parks, including Panagal park in T Nagar, are expected to be taken over to build underground stations. The trees will make way for alignment and depots at Madhavaram, SIPCOT and Poonamallee bypass.A survey by RITES, a consultancy firm that prepared the project report, identified 15 native species in localities along the alignment that will be affected. It includes mango, peepal, neem, country almond and palmyra palm. A 7,104sqft forest near Medavakkam Koot Road Bus Stop on corridor-5 will be taken over for a proposed metro station.As green cover disappears to make way for concrete structures, so will its several benefits. It is estimated that chopping more than 2,000 trees will lead to decreased carbon dioxide and low oxygen levels. To compensate for the loss of greenery, CMRL has undertaken an ambitious plan to plant 12 saplings for every tree axed. Also, for the forest land, two times its size will be made available to the forest department for redevelopment. CMRL will spend an additional Rs2.5 lakh for development of a non-forest land, an amount not included in the project cost.Since there is no space, the green cover will be irreparably lost in these zones. Transplantation of existing trees and not planting of new saplings would be right approach to saving greenery, suggest experts. "There is no question of planting saplings because there is no space in the city. Transplantation is the way. The state has achieved 70% success rate of survival of transplanted trees, but much depends on the species, size and damage it has undergone," said retired Madras Christian College botany professor D Narasimhan. "Of course, for every tree axed, there will be reduced carbon dioxide absorption."Nearly 2,500 trees were axed, including more than 130 at the 8.8-acre Thiru Vi Ka park at Shenoy Nagar, to build the 45km phase-1 network. While the park is yet to be restored, another 400 trees were cut down to build the phase-1 extension in north Chennai.