“I was shutting down the windows when I saw a tree fly past our house. It took me some time to realise what I just saw. I had never encountered a storm like this,” recalled Abhirup Chakraborty, a south Kolkata resident. He was referring to the cyclone Amphan that had battered West Bengal on May 20, 2020.
According to reports, the wind speed of the cyclone, when it struck the city, was 130 kmph, rising up to 185 kmph in North and South 24 Parganas. The Kolkata Municipal Corporation (KMC) stated that more than 5000 trees were uprooted as a result of this storm. Several trees fell on houses while others lay across streets, blocking transportation, disrupting electricity and severing telephone and broadband cables.
Dr. Punarbasu Chaudhuri, Assistant Professor, Department of Environmental Science, University of Calcutta, told BE, “Due to this catastrophe, we have lost a huge amount of vegetation, both in the urban and rural sectors as a lot of trees have fallen on irrigation lands.”
Asish Banerjee, Minister-in-Charge, Department of Agriculture, Government of West Bengal, has reported to the media that the farming sector across 14 to 23 districts of West Bengal were affected due to the Cyclone Amphan. It is estimated that Burdwan (East), which is the largest paddy growing district in the state, suffered a loss of about `3 billion.
Chaudhuri said, “Due to the uprooting of so many trees, the supply of oxygen will be affected. Apart from that, the trees perform various subsidiary functions in urban areas. For instance, they arrest Suspended Particulate Matter (SPM). Now, with a reduction in the number of trees, dust pollution will tend to rise.” Environmentalist Somendra Nath Ghosh recently told The Hindustan Times, “More than a third of the roadside trees in the city seem to have been wiped out. We foresee a serious rise in PM 2.5 levels from the first week of September, when an estimated eight lakh vehicles will hit the roads post-lockdown.”
Mangroves – a natural barrier
The West Bengal Chief Minister Mamata Banerjee has announced that the state government will plant five crore mangrove trees in the cyclone-hit Sundarbans within a month. However, experts are of the opinion that the plantation of mangroves is a difficult process and several challenges are associated with it. For rearing the mangrove seeds, a nursery bed is required and then these seeds need to be transplanted. Chaudhuri pointed out, “The preparation of seedlings is a big challenge in case of the Sundarbans as the propagules from which the seeds germinate are collected and used by the local people as fuels when they are floating. It is impossible to regenerate the mangrove forest without these propagules.”
The uprooting of a numbers of trees is a huge loss for Kolkata. Environmentalists say that this canopy around the city had been created in the last 60-70 years. Also, there had been unplanned plantations around the city. Now species selection should be given primary importance while planting trees. For instance, trees like radhachura are very common in Kolkata as they grow quickly but are very vulnerable to storms. Chaudhuri stated, “The purpose for which the trees are planted should also be considered. For instance, if we are planning roadside plantations, we should select trees with high Air Pollution Tolerance Index (APTI). Similarly, if we are planting for salt stabilisation, we should select trees with high root penetration.”