Analysis: Nearly Half of Trees Planted in Delhi's Central Ridge Are Unsuitable for Ecosystem
With June about to end, Butea monosperma — commonly known as dhak or 'flame of the forest' — has entered its fruiting season. The tree's fiery orange-red blossom gives way to broad, papery seed-pods that will soon disperse with monsoon. It is a characteristic species of Delhi's dry deciduous forests and among the first trees to naturally regenerate degraded landscapes. Yet it represents only part of the recent plantation choices on the Capital's ecologically sensitive Ridge.
An analysis by The Indian Express of plantation records from the Delhi Forest and Wildlife Department, covering drives over the last four years in Central Ridge, shows that out of at least 22 species planted, only seven are characteristic Ridge species. Nine, or nearly half of them, are considered unsuitable for the Ridge ecosystem, including three exotics. Six are native species not naturally found in the Ridge but considered only marginally adaptable under sustained irrigation and nutrient input. The Central Ridge stretches across 864 hectares, covering Dhaula Kuan, Sardar Patel Marg to Mandir Marg, institutional zones, and stretches of Inderpuri and Naraina industrial edges.
The Indian Express reached out to the Forest Department in this regard but did not get a response.
A decadal Working Plan (2026-27 to 2036-27) recently rolled out by the Forest Research Institute (FRI) for the Delhi government noted that invasive species account for 44.13% of relative dominance in parts of the Central Ridge. In some zones, regeneration patterns are more severe: invasive species such as Leucaena leucocephala show a regeneration stocking percentage of 100%, with internal observations of a potential long-term shift in forest composition if unchecked. 'While the current canopy remains predominantly native, future forest composition may be entirely overtaken by invasive species if unchecked,' the plan noted, warning of risks to biodiversity and ecosystem stability. It recommended targeted removal of invasive seedlings and active promotion of native regeneration.
Species lists from Central Ridge plantation drives between 2021 and 2025 include a limited set of Ridge-appropriate natives such as dhak (Butea monosperma), khair (Acacia senegal), Holoptelea integrifolia, and Cassia fistula. These species are naturally adapted to dry deciduous conditions and form part of the historical Aravalli-Ridge assemblage. However, a significant share of planted species fall outside this ecological range.
Exotic species include Sausage tree (Kigelia africana), Jacaranda (Jacaranda mimosifolia), and Jungle Jalebi (Pithecellobium dulce). Others such as Kadamba (Neolamarckia cadamba), Kachnar (Bauhinia variegata), and Bakain (Melia azedarach) are not characteristic of Ridge ecosystems and typically require higher moisture availability. A third category includes native Indian species that are not naturally part of the Ridge ecosystem, such as banyan (Ficus benghalensis), Peepal (Ficus religiosa), Semal (Bombax ceiba), and Bael (Aegle marmelos). While ecologically versatile, these species belong to different forest types.
Environmentalist and author Pradip Krishen cautions against treating 'native' as a uniform category. 'Contractors tend to pick species that are convenient, easily available in bulk rather than species that are actually appropriate for a specific landscape like the Ridge,' Krishen told The Indian Express. 'Native is a highly misleading term. What grows in one part of Delhi at the Yamuna khadar or other moist alluvial systems cannot be assumed to be suitable for the Ridge, which is a dry, rocky ecosystem with very different soil and moisture conditions,' he said.
