The Plantation Drive – Numbers and Concerns

Delhi Ridge Reforestation: How Misplaced Species Threaten Dry Deciduous Ecosystem

The Indian Express analysis of Delhi Forest and Wildlife Department records shows that out of 22 species planted on the Central Ridge over the past four years, only seven are native to the dry deciduous habitat. Nearly half of the saplings – nine species – are deemed unsuitable, including three exotics, while invasive plants such as Leucaena leucocephala now dominate 44 % of the canopy. The plan’s own Working Paper warns that unchecked spread could rewrite the ridge’s forest composition within a decade.

The recent greening campaigns have been driven by a mix of municipal mandates and contractor‑led contracts, yet the species mix reveals a mismatch between intent and ecological suitability.

• ▸864 hectares of Central Ridge span from Dhaula Kuan to Mandir Marg, intersecting institutional and industrial zones.
• ▸22 different tree species were introduced between 2020‑2024.
• ▸Only 7 species (≈32 %) belong to the ridge’s natural flora.
• ▸9 species (≈41 %) are classified as unsuitable for the ridge’s soil and moisture regime.
• ▸Invasive species account for 44.13 % of relative dominance in surveyed plots.

The dominance of fast‑growing, nitrogen‑fixing exotics reflects a short‑term focus on canopy cover rather than long‑term ecosystem resilience. Contractors often source seedlings in bulk, favouring species that survive initial planting but falter under the ridge’s arid conditions, leading to higher maintenance costs and eventual loss of biodiversity.

Understanding Delhi’s Dry Deciduous Zone

Delhi’s ridge lies within a dry deciduous forest belt that experiences an average annual rainfall of 650 mm, concentrated in the monsoon months of July‑September. Soils are shallow, rocky, and low in organic matter, supporting drought‑tolerant pioneers such as Butea monosperma (dhak) and Holoptelea integrifolia (kanju).

• ▸The natural vegetation zone is classified under the Indian Forest Classification as “Very Dry Forest” (rainfall 500‑800 mm).
• ▸Characteristic species exhibit deep taproots and leaf‑shedding during the dry season to conserve water.
• ▸The ridge’s elevation ranges from 200 m to 250 m above sea level, influencing micro‑climatic gradients.
• ▸Native fauna, including the Indian fox and various ground‑nesting birds, depend on open canopy structures typical of this zone.

These ecological traits mean that species adapted to moist alluvial soils – such as banyan or peepal – cannot thrive without supplemental irrigation, which the city’s water‑stress context cannot sustain.

Invasive Species and Ecological Risks

Leucaena leucocephala, a fast‑growing legume introduced for rapid biomass, now shows a regeneration stocking percentage of 100 % in several ridge sectors. Its aggressive root system outcompetes native seedlings, alters soil nitrogen cycles, and creates conditions favourable to other non‑native grasses.

• ▸The invasive’s canopy density exceeds 70 % in surveyed plots, reducing light penetration for understory plants.
• ▸Its seed dispersal range extends up to 30 km via wind and water runoff, facilitating spread beyond the ridge.
• ▸The Forest Research Institute’s 2026‑2036 Working Plan flags Leucaena as a priority for removal to prevent long‑term compositional shift.
• ▸In comparable Indian dry forests, invasive dominance has led to a 15 % decline in native shrub cover over five years.

Unchecked proliferation threatens not only biodiversity but also the ridge’s role as a carbon sink and a buffer against urban heat islands. The altered species mix could diminish the area’s resilience to climate‑induced droughts, amplifying the city’s vulnerability to heatwaves.

Policy Framework and Management Options

India’s forest governance rests on the National Forest Policy 1988, which emphasizes the protection of natural forest types and the use of native species for afforestation. The policy mandates that any plantation on ecologically sensitive zones must undergo a site‑specific ecological assessment.

• ▸The Delhi government’s recent Working Plan recommends systematic removal of invasive seedlings and the propagation of drought‑tolerant natives like Butea monosperma and Holoptelea integrifolia.
• ▸It proposes a monitoring protocol using remote sensing to track canopy composition annually.
• ▸Funding allocations for the ridge’s restoration are earmarked under the city’s “Green Delhi” budget, amounting to ₹150 crore over the next five years.
• ▸Community participation schemes are suggested to involve local NGOs in seed collection and nursery management, aligning with the policy’s participatory approach.

Effective implementation will require coordination between the Forest Department, municipal bodies, and academic institutions to align species selection with the ridge’s physiographic constraints. A science‑backed, locally adapted afforestation model could transform the ridge into a living laboratory for urban dry‑forest restoration.