Why we can’t bet on plantations and sacrifice thousands of trees in Delhi

Undoubtedly, Delhi is still one of the greenest capital cities of the world. Not just the ridge forests, massive trees lining major roads shelter us from Delhi’s harsh sun.

The Sundar Nagar section of Mathura Road was one such stretch. The expansive tree canopy on both sides overlapped to hide the sky and you felt like you entered a green tunnel. But it took a summary decision by Public Works Department to chop down those robust trees this month even as seven other neighbourhoods battled to save at least another 14,000 trees.

The government, of course, has promised to plant ten saplings, presumably somewhere in the outskirts of Delhi, for cutting every tree. But as successive audits and field reports — the latest one by Hindustan Times last week — have revealed, replacement is pretty much hogwash.

It makes no sense to alter the local ecology of a neighbourhood by felling its full-grown trees and “compensate” by planting some saplings elsewhere. It is difficult to pinpoint due to poor record-keeping but the survival rate of these plantations is anyway low.

Even if the chopped trees are replaced by planting saplings in the vicinity and they somehow survive, it will be a decade or two before the canopy develops fully and any real compensation takes place. Given the acute air pollution Delhi faces, that is simply too long a window.

Worse, due to wrong choices of species for plantation, the replacements will not provide even a fraction of ecological services the originals provide now. The loss of a jamun tree, for example, can never be compensated by growing a diminutive palm or a champa.

When trees are felled for intensive construction, there is barely any space to regrow big native species. So we make do with smaller plants and hedges. Look at East Kidwai Nagar where 1,825 trees were axed for high-rises. As reported by HT last week, concrete fountains and walkways and landscaping have left space for planting mostly ornamental trees.

What is a Ficus benjamina (a weeping fig), native to Thailand, or Bismarckia from Madagascar anyway doing in the semi-arid Kidwai Nagar of South Delhi? It is not just the case of the recently developed areas, plantations in Delhi have mostly favoured non-native, evergreen varieties because these look pretty and grow fast.

While all exotic tree species are not invasive, even those favoured for their ornamental appeal cannot compensate for the ecosystem services provided by hardy native species such as amaltas, palash, pilkhan, kareel or peelu. Trees native to an area have adapted to its soil and ecology over thousands of years. One can’t say the same for aliens such as eucalyptus, a common roadside tree in Delhi, which have turned out to be a water-guzzler, or gulmohar, which can’t regenerate on its own.

Even within the city, explains ecologist CR Babu, conditions differ. So arjun, semal or jamun, which thrive near the riverbed for they can withstand floodwaters, may not be ideal for the ridge where dhau or ronjh, species demanding less water, can flourish.

What’s more, exotic trees don’t support native fauna. Species such as guava, mulberry, ber, bael or jamun are important to sustain squirrels, bees, butterflies and birdlife in Delhi — rated second after Nairobi for its avian population. Monkeys have become dependent on humans because fruit and berry-bearing trees in the ridge are mostly gone.

Native trees are adapted to the micro-climate and act as dust traps and assimilate pollutants from the air. Leaves of the alien, ornamental varieties cannot perform these functions. Today, the ridge does not provide an effective sink to dispel heat-islanding or block dust storms from the Thar because exotic invasive species, such as vilayti kikar (Prosopis juliflora) and subabul (leucaena leucocephala) have taken over the native ecosystem, points out Babu.

These exotic species were planted by the forest department early last century when the British wanted a less barren, greener look for the ridge, wrote Pradip Krishen in Trees of Delhi. Surprisingly, the same motivation still continues to dictate our plantation drives. Yet, we are supposed to bet on plantations and sacrifice thousands of trees.

Delhi is not an exception. Across India, rapid loss of dense forests to development is being ‘compensated’ on paper by factoring in fast-growing plantations. But if public opinion of the privileged at the nation’s power centre fails to save the Capital’s trees, imagine the chances those infinitely less influential communities have of saving their forests elsewhere in the country.