Blame bad planning for tree-falls

In case of thundershowers which have been occurring frequently nowadays, it’s best you remain alert about the dangers posed by falling trees in Bangalore. Trees have turned your enemies, ironically in a city that is known for its tree cover.

On Wednesday night alone, during the thundershowers and hailstorm, 22 trees got uprooted across the city, bringing electric lines down with them—miraculously not injuring anyone. But over the past few days, the daily thundershowers in the late evenings have damaged several cars and at least 10 houses in different locations in the city.

If you are wondering why such an irony in this city, blame the authorities for continuing with the British legacy of sowing exotic trees. The British did so at a time when Bangalore was still a small town. It was then just a rest and recreation centre for its troops. But now, the Bruhat Bengaluru Mahanagara Palike (BBMP) has blindly continued that legacy without thinking whether these trees are strong enough as they are not endemic to India.

Biodiversity expert Harish R Bhat says: “Over 70% of Bangalore has exotic species like acacia and avenue trees. These trees were brought by the British for their aesthetic value. But, these are not very strong.”

He continues: “The BBMP, on its part, has worsened the situation. They have built pavements very close to the trees, suffocating the roots. Apart from this, the exotic varieties have larger and wider crowns (the part of the tree covered with leaves) but smaller roots. Hence they get uprooted when gusty winds blow such as during a thunderstorm.”

He explains that these big exotic trees are also very old and feeble. “They are hollow and also weak which makes them vulnerable to rains and gusty winds. What the BBMP can do is to list these trees and resort to tree surgeries to ensure they remain standing,” he says.

“Past year when there was drought, the soil had very little water. Now there is sudden gush of water and this has loosened the soil leading to uprooting of trees.”

AN Arun Kumar, a scientist at the Institute of Wood Science & Technology (IWST), whose area of specialisation is tree improvement, said the way forward would be to rely on more research.

“It is pertinent to study the root architecture of the tree species. My suggestion is to study the root movement of avenue trees (urban trees) because right now even minimal wind is enough to uproot them. That’s because they don’t have deep roots and there is not much of information available about root architecture.”

Deputy conservator of forests, BBMP, P Chandrashekhar, admitted that the roots of the trees are weakened due to digging of roads for widening and drain repair works. He said strong winds only further worsen the situation. However, he refused to comment on the issue of exotic trees.

Why this issue has become worrisome is that the meteorological department has forecast a good monsoon, which means more rain for the city. This, in turn, would indicate a higher level of danger in the days to come from the very trees which gave cooling shade during the hot summer.

However, Bhat has a suggestion: “(Planting of) More local varieties of trees is the solution for Bangalore. From mangoes to jackfruits, from black plums to banyan trees, the city needs more of these local varieties to avoid such contingencies in monsoons.”