Project to reduce monopoly of vilayati kikar from Central Ridge of Delhi on track

However, environmental experts said deeming the project successful in a year based on a decent survival rate may be too premature, as the vilayati kikar shows allelopathic effects, meaning the tree releases compounds that make it difficult for other native species to grow nearby

jasjeev.gandhiok@hindustantimes.com

vilayati kikar is an invasive Mexican tree species, introduced by the British in Delhi in the 1930s. (Ravi Choudhary/HT Archive)

The pilot project on ecological restoration of the Central Ridge, which aims to add native Aravalli plant species around the invasive vilayati kikar tree (prosopis juliflora), has proven to be successful so far, according to forest officials, with more than 90% of the saplings planted in April 2022 over 15 hectares area surviving the process.

The forest and wildlife department will now proceed with the same methodology in more parts of the Ridge, which involves using the ‘canopy lifting’ technique. The technique prunes the top canopy of the vilayati kikar to allow sunlight to penetrate and help the native trees grow alongside, officials said.

Forest officials said the native species planted include hingot, banyan, bahera, chamrod, pilkhan, amaltas, siras, arjun, dhak, palash, acacia, khair, bitter gourd, gular, harsingar, etc. Pilkhan, siras, and arjun are doing the best among these so far, with some saplings growing up to a height of 10 feet already, officials said.

The vilayati kikar is an invasive Mexican tree species, introduced by the British in Delhi in the 1930s. The tree has systemically taken over the Delhi ridge, making it difficult for other native species to grow. The roots can grow over 50 metres deep, depleting groundwater, and its leaves contain toxic chemicals which prevent them from undergoing microbial degradation. The trees also make it difficult for native species to germinate around them.

The Delhi government started the pilot in a segment of the 864-hectare-wide Central Ridge, along the Vande Mataram Marg, in April 2022. Delhi environment minister Gopal Rai planted the first batch of native saplings. The forest department said that though the project was initially devised to eliminate vilayati kikar, the trees will now remain except for pruning at the top.

“We will not eliminate vilayati kikar anymore as it forms a part of the overall green cover in Delhi. The trees also carry out carbon sequestration. The aim of the project now is to reduce the monopoly of this tree and to introduce other tree species to bring diversity,” a senior forest official aware of the matter said.

He also said that to make the native saplings grow successfully, they are being provided nutrients through manure every two to three months, along with regular water, once to twice a week. The official said the forest department will also share a report with the environment minister once a review meeting is held.

However, environmental experts said deeming the project successful in a year based on a decent survival rate may be too premature.

Pradip Krishen, environmentalist and author of the book ‘Trees of Delhi’, said vilayati kikar shows allelopathic effects, meaning the tree releases compounds that make it difficult for other native species to grow nearby.

Vijay Dhasmana, an ecologist and the curator of the Aravalli Biodiversity Park (ABP) in Gurugram, shared similar concerns. “Wherever successful restoration projects have been undertaken, we have had to remove vilayati kikar eventually. In the present scenario, considerable efforts will be required to water or provide nutrients to certain species, particularly the likes of pilkhan or arjun,” said Dhasmana.