Forest dept asked for plan to weed out 3 invasive tree species in Delhi

Of the three, vilayati kikar is the most harmful, as the Mexican invasive species introduced by the British in the 1930s in Delhi quickly taking over large parts of the ridge, experts said.

The proliferation of three rapidly growing tree species of vilayati kikar, subabul and eucalyptus in the capital needs a plan to contain and exterminate them, Delhi’s State Environment Impact Assessment Authority has asked the forest department in its latest meeting, after the Delhi Urban Art Commission raised concerns on their adverse impact on local ecology.

Subabul is removed from a park in Defence Colony in New Delhi. Subabul, the third tree flagged in the list, also comes from Mexico and was introduced by the forest department for fuel and fodder, but it has grown too rapidly, expanding well beyond where it was initially planted. (HT Photo)

A pilot project to remove vilayati kikar is already underway and the forest department is also looking at ways to deal with other invasive species like subabul and lantana, officials said, requesting anonymity.

“We are exploring ways to remove vilayati kikar from the central ridge. If the pilot is successful, a similar approach could be adopted for subabul and lantana, which are similarly invasive species in the ridge,” a forest official said. “As these trees still form a part of Delhi’s green cover, they cannot be removed at the same time.”

The recommendation was made by the impact assessment authority in its meeting held on December 23. HT has seen the minutes of the meeting. In a September 29 letter to the State Expert Appraisal Committee, the chairman of Delhi Urban Art Commission had highlighted the issue of three invasive species that are not native to Delhi but are creating an imbalance in its ecology.

“These species are invasive and multiplying rapidly, crowding out native species and their symbiotic flora and fauna. These include vilayati kikar (prosopis juliflora), subabul (leucaena leucocephala) and finally, eucalyptus,” the letter said. This proposal was forwarded to the assessment authority on November 25.

“The SEIAA in its meeting held on December 23, 2022, has approved the recommendation of the SEAC to forward the reference from DUAC to the forest department of Delhi for suitable examination and necessary action, with further intimation to both SEAC and SEIAA,” the minutes read.

A plan has to be drafted by the Delhi forest department on how these species will be tackled in the long-run, a SEIAA member said. “They will inform us about the action plan and how they intend to remove these exotic species,” the member said, declining to be named.

Of the three, vilayati kikar is the most harmful, as the Mexican invasive species introduced by the British in the 1930s in Delhi quickly taking over large parts of the ridge, experts said.

“Vilayati kikar forms nearly 70% of all trees in the ridge at present. Its roots grow over 50 metre deep, so it depletes the groundwater table wherever it grows,” said C.R Babu, head of the Centre for Environment Management of Degraded Ecosystems. “The main problem with it is that it does not allow native species to grow around it.”

Eucalyptus, which came from Australia, is not invasive in nature, but uses a lot of water as it is a fast-growing tree, Babu said. “Wherever it grows, the groundwater level will drop rapidly. It also shows allelopathic effects, meaning the tree releases compounds which make it difficult for other native species to grow nearby,” he said.

Subabul, the third tree flagged in the list, also comes from Mexico and was introduced by the forest department for fuel and fodder, but it has grown too rapidly, expanding well beyond where it was initially planted.

While subabul is not as harmful as vilayati kikar, it still propagates quickly, according to Faiyaz Khudsar, scientist in-charge at the Yamuna Biodiversity Park in north Delhi. “Like vilayati kikar, it does not allow native species to grow around it,” he said.

There has been an explosion of subabul over the last decade or so, said Padmavati Dwivedi, an activist. “All three species are not native, grow fast and are depleting the groundwater table,” she said, recommending systemic action against them.