Getting to the root of Bengaluru’s tree-falls

From competing with high-rises for sunlight to infrastructure projects for their very existence, the trees of Bengaluru are up against many odds. While Bengalurians wax eloquent about the city’s green cover, too few do anything to stop trees from being choked at their roots or turned into billboards and wire hangers

Seventy-six-year-old Bhadraiah takes time off from his stall in Jayanagar III Block, where piping hot bajjisare made, when asked about a grand banyan tree on the road where his shop and house are located. “I’ve seen this tree ever since I moved here 50 years ago. Even the Bruhat Bengaluru Mahanagara Palike (BBMP) won’t take it down, nor will the residents here allow it, because it’s a sacred tree and it’s dear to all of us,” he says.

In east Bengaluru, at BEML Gate on the ever-busy Suranjandas Road, another tree has no such luck. Its roots stand exposed, almost unnaturally manicured, as work goes on beside it on the construction of an enclosure for the Kempegowda statue that was installed here.

Rapid loss of green cover

Bengaluru, once known as the Garden City of India, in its transition to becoming the IT capital, has seen a rapid loss of green cover. As extreme weather conditions are becoming increasingly frequent, and with experts also flagging the urban heat island phenomenon, the need to pay more attention to the ecology of the city has become more apparent than ever.

Ecologists say Bengaluru’s tree diversity is much larger compared to other big cities. Harini Nagendra, Director of the School of Climate Change and Sustainability at Azim Premji University (APU), said the city has a large palette of over 50 species that have historically been used for greening in different areas.

“In most other large cities across the world, a handful of species predominate, reducing biodiversity and also making the species prone to diseases that can sweep through quite quickly, damaging old trees. Partly because of the city’s colonial heritage, and partly because of an older Indian tradition of planting a variety of keystone species like peepal and banyan, Bengaluru has always drawn on a large variety of trees,” she said.

Offering an example, she said one species — the ash tree — makes up close to 20% of all trees in Chicago, but this tree has been subjected to attack by the emerald ash borer, a beetle from Asia that spreads quickly, and now threatens the survival of hundreds of thousands of ash trees in Chicago and many other midwestern US cities.

“Increasing tree biodiversity helps make urban tree populations more resistant to such diseases, and Bengaluru has an advantage here. Some of this is, unfortunately, changing. For instance, in sacred spaces – temples, churches, mosques and cemeteries — we find trees of high species diversity, as well as on roadsides. But in gardens and parks, we find a few species predominate. Similarly, plant diversity is very low in landscaped gardens but high in informal settlements, especially the diversity of native plants, which many of these households grow to use in cooking and as herbal medicines,” said Harini.

Ganesan Rengaian, Senior Fellow, SM Sehgal Foundation Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology and the Environment (ATREE), added that Bengaluru has a deeply rooted identity with plants, especially trees, historically because many administrators associated with the city valued the natural assets as indispensable and their contributions to the welfare of the humanity.

“The history can be traced back to administrators such as Kempe Gowda, followed by Hyder Ali and Tipu Sultan. The monarchs also include the Raja of Mysore. Under British management and Tipu Sultan, the city’s greenery got a connection with countries such as Australia, Africa, and Central and South American regions. These personalities introduced a lot many plants at Lalbagh garden because they appreciated the value of plants as natural assets,” he explained.

He added that with its salubrious climate, Bengaluru was considered by Britishers as a transit camp for plants, and they introduced many temperate vegetables and fruits in addition to various tree species. The Tabebuias, Jacarandas, and Spathodeas become the iconic plants of Bengaluru as the city’s earlier “naked” landscape was made colourful, he added. “An indigenous community called Thigala who had a green thumb for the plants brought by Mughals and Europeans also played an important role as horticulturists and the ‘garden city’ tag,” he said.

Planning around trees

But the city’s trees have often been victims of “developmental work”. Experts say it is often avoidable.

“City planners come up with the developmental work plan on purely engineering-based considerations — as if the trees do not exist — and then come to the tree authorities with a binary request — to approve or decline permissions to cut trees. Then environmentalists, who bat for the trees, are accused of being anti-development. But there is another way. What if the alignment of the metro, road widening and other projects were made on the basis of plans that also showed the locations of the trees — so that other ways of planning these projects could be considered?” said Harini.

She mentioned the example of parts of Sarjapur Road, where during road-widening work a decade ago, trees on either side of the road were retained as medians in the new, wider road. Similarly, for the metro projects, minor changes in the location of the commercial complexes could save several large trees, but this was not considered in the initial design, she added.

As if this is not enough, of late, trees have come under the scanner for causing fatalities apart from damages to infrastructure. Every year, especially during the monsoon season, we come across instances of tree-falls in Bengaluru, sometimes resulting in fatalities. This August, a 49-year-old auto driver succumbed to severe head injuries when a tree fell on his autorickshaw in Vijayanagar. BBMP Forest Cell officials confirmed that weakened roots caused the tree-fall. What’s ailing our trees?

Why tree falls

Ganesan says depending on the species, trees are either short-lived or long-lived. While fatalities and damages by trees are not new, incidences of damages caused to trees have increased in the recent past, he pointed out.

“First, we plant inappropriate species at inappropriate locations and naturally, the life of the trees gets further curtailed. When gusty winds, especially during the summer rains, pass through the narrow lanes and roads lined with tall buildings, the ‘funnelling’ effect of the wind breaks the branches or uproots the trees,” he says.

Cementing and asphalting the surface on the base of the tree, pruning the branches leading to an imbalance of the tree trunk, high frequency of passing vehicles on the roads, damage to the bark by nailing, girdling the branches and trunk with ropes, wires and banners, burning litter around the tree trunk could all be the other reasons killing the trees. “The new phenomenon of using trees as poles to hold cables should be taken seriously as part of tree management,” he explained.

Harini added that the choice of species also has a lot to do with this. Some species, like the Gulmohar and Singapore Cherry, have weak roots and are prone to falling after a few years; others, like the rain tree and neem, tend to be deep-rooted and more stable, with a longer life span, she said. This August alone, a total of 53 trees had been uprooted, and 92 tree branches had fallen in the city. 

Competing for light

BBMP officials agree that lifespan, as well as damage to the roots of the trees for various projects, injures the trees and weakens them. B.L.G. Swamy, DCF, BBMP, also spoke of another problem that has emerged with high rises. “Trees with linear heights are increasingly having to compete with high rises for sunlight. This makes them crown heavy, thereby prone to damage.”

Ganesan explained this further, saying branches and leaves are specifically arranged in a tree to capture the maximum amount of light and vary from the temporal and spatial availability of light. “In search of light, the branches keep growing or fail to grow, leading to the ultimate death of the tree or the tree looking unnatural,” he said.

While there are approximately 20 lakh trees in BBMP areas, Swamy said the first tree census, which began this January, is expected to be completed in three months and give a clearer picture. “We are also discussing the possibility of ascribing a size for avenue trees to avert danger in the future,” he added. 

Harini said we need a multi-pronged strategy to protect existing green cover, spatially link green patches in the city to improve biodiversity, and conduct extensive tree plantation to combat the losses of tens of lakhs of trees in the past couple of decades. First, we need to identify and protect all heritage trees, especially those that are old and large, which are an important part of the city’s heritage and cannot be easily replaced by planting young saplings.

These heritage trees should be monitored for their health, and any new or ongoing infrastructure projects should factor in their location from the start to minimize damage to them, using approaches such as redesign and realignment wherever possible, in consultation with civil society and tree experts.

Second, we need to link patches of green spaces such as wooded roads, small pocket parks, and the large botanical gardens and other wooded spaces like IISc, Bangalore Palace, GKVK, etc — by planting smaller sections of trees and working with private land owners to increase connectivity between these green patches — so that endangered wildlife like the slender loris and mobile species like birds and butterflies can easily move from one location to the other, instead of getting trapped within increasingly shrinking green spaces as is currently the case,” she said.

Plant wisely

She also stressed the need for a well-planned tree planting policy – planting aggressively but wisely and staying away from planting trees like Eucalyptus or Acacia auriculiformis on lake beds, but instead planting a diversity of trees that provide flower, fruit and shade in home gardens, corporate, residential and educational campuses, government and military-owned areas, streets, gardens and manicured lawns.

APU has published a free “Tree planting guide for houses and apartments in Bengaluru”, which, apart from a list of trees, also guides citizens on root barriers and treating trees and plants affected by pests and diseases.

 Trees for Bengaluru homes and apartments

1. Avocado (Persea americana)

2.Chikoo (Manilkara zapota)

3. Coral jasmine (Nyctanthes arbor-tristis)

4. Crape jasmine (Tabernaemontana divaricata)

5. Curry leaf (Bergera koenigii)

6. Custard apple (Annona squamosa)

7. Drumstick (Moringa oleifera)

8. Frangipani (Plumeria obtusa)

9. Guava (Psidium guajava)

10. Henna (Lawsonia inermis)

11. Hibiscus (Hibiscus rosa-sinensis)

12. Hummingbird tree (Sesbania grandiflora)

13. Indian beech (Pongamia pinnata)

14. Indian mast (Polyalthia longifolia)

15. Lipstick tree (Bixa orellana)

16. Mango (Mangifera indica)

17. Neem (Azadirachta indica)

18. Peacock flower (Caesalpinia pulcherrima)

19. Pink trumpet tree (Handroanthus impetiginosus)

20. Pomegranate (Punica granatum)

21. Potato tree (Solanum grandiflorum)

22. Singapore cherry (Muntingia calabura)

23. Star gooseberry (Phyllanthus acidus)

24. Weeping bottlebrush (Melaleuca viminalis)

25. Yellow oleander (Cascabela thevetia)

26. Yellow tabebuia (Tabebuia aurea)

SOURCE: “Tree planting guide for houses and apartments in Bengaluru” by Azim Premji University

Published - September 20, 2024 06:00 am IST