Bengaluru: How many trees should be axed for a 2.3-km Hebbal tunnel? 1,128, from the leafy stretches of Ballari Road, Veterinary College campus, and around Hebbal Lake. Or 490 trees for every 1km of quick travel through the tunnel.GBA’s tree officer has published a notice inviting objections to the felling move. Citizens have pointed out that the civic body’s website does not provide complete details, including the species and locations.The project is being executed by Bangalore Development Authority, whose engineer-member has sought permission from the GBA tree officer for the felling.Citizens questioned how objections could be filed without access to complete tree-wise details. A citizen-led survey carried out over the past two months has documented several plant and animal species along the alignment and surrounding areas. Using iNaturalist, an online citizen-science platform, 21 contributors have uploaded geotagged photographs of species including banyan, peepal, ficus and cannonball trees, besides birds such as spotted owlets. The surveyors said the list was not exhaustive.Their documentation includes close to 40 native tree species and 20 other species, including ornamental trees. These include Madras thorn, jamun, Indian gooseberry, false ashok, pongamia and rain tree, besides jacaranda, copperpod, gulmohar and tabebuia.The group has also identified mature and heritage fig trees, including a banyan estimated to be about 100 years old. It said native figs such as peepal, banyan, cluster fig, Mysore fig and white fig provide food and habitat for insects, birds and small mammals.An active resident involved in the survey said Veterinary College campus had several large banyan and fig trees with extensive lateral root systems. “All around the trees are being cut and it is also being concretised. What will happen to groundwater recharge? The trees are being removed from a hydrologically sensitive area,” she said.The resident said mature trees at institutional campuses needed to be retained as there was little space in the city for such large trees.Birdwatching database eBird records 183 bird species at Hebbal Lake and 95 on Veterinary College campus. The group said the trees along the route form a green corridor between the lake and Veterinary College campus, providing canopy connectivity and roosting spaces for birds, including wetland species.The underground road between Hebbal Junction and UAS Staff Quarters, via Karnataka Veterinary, Animal and Fisheries Sciences University, is under construction using the cut-and-cover method.