Invasive subabul takes root, is now Delhi's dominant tree

For the best part of a decade, Delhi's agencies have focused on weeding out the vilayati kikar (prosopis juliflora)—an invasive tree species from Mexico—from the Capital's landscape.

- Snehil Sinha and Jasjeev Gandhiok

NEW DELHI: The reason—the species propagates quickly, has deep roots, and does not allow Delhi's native species to grow around it. But even as that war continues, its compatriot, the subabul (leucaena leucocephala), has slowly taken over parts of the city, and has become the most dominant tree species in Delhi's urban spaces.

The latest issue of the India State of Forest Report (ISFR)—a biennial publication by the Forest Survey of India (FSI), which falls under the Union ministry of environment, forest and climate change—released on December 21, 2024, stated that subabul has, in a first, overtaken all other local species of fauna.

This is a problem because like vilayati kikar, Subabul is also a hardy tree which propagates quickly and is allelopathic in nature, meaning it secretes chemicals that do not allow any other species to grow around it. Indirectly, it prevents growth of Delhi's native trees, thus taking over a landscape fairly quickly.

Till 2021, the most commonly found tree in Delhi's urban spaces was the neem (azadirachta indica), with the mulberry, the ashok and the peepal close behind. Renowned environmentalist and author Pradip Krishen said experts have long been warning Delhi's forest department and other agencies of the dangers of subabul, but no serious effort has been made to stem the tree's unchecked growth.

"Till a few years ago, we were still at a point where we could warn the agencies, but now it is just everywhere. All across the southern and central Ridges, there are large patches of only the subabul tree. When you drive along the central Ridge, there is a large area of thick subabul forest," said Krishen.