Is Conocarpus the real culprit behind Karachi’s killer heatwaves?
ISLAMABAD: After a dramatic rise in the frequency of dreaded heatwaves, residents of Karachi initiated a social media campaign against a Mangrove species ‘Conocarpus’, claiming it to be one of the reasons behind the city’s heat woes.
With the seemingly sudden rise in the city’s temperature, the blame had to be shifted somewhere after all.
The posts on social media urged residents to stop planting and even uproot these trees, which were planted in abundance in the metropolis during former city mayor Mustafa Kamal’s tenure.
How much truth the claim holds and to what extent this plant species can be blamed for Karachi’s heatwave needed some substantial evidence and discussion.
Opinion of researchers and scholars and tried to take an in-depth look into the matter.
Dr Zafar Iqbal Shams, a professor at the Department of Environmental Sciences, University of Karachi, was staunchly against uprooting the Conocarpus plants.
Lamenting the trend of monoculturing in the metropolis, he said that since the past few decades only one plant species is being grown in abundance. “Previously it was Eucalyptus and Lignum and now it is Conocarpus,” he said, adding that urban foresters do not promote planting only one species as exposure to a disease can end up infecting the entire tree population.
In the same breath, however, Dr Zafar strongly opposed the idea of chopping these trees down, which he said would lead to a rise in temperature.
“High-rise buildings should have green cover, while vertical gardening can also save buildings from absorbing heat,” he pointed out an alternative to combating the heatwave.
Concrete high-rise buildings and bituminous black roads trap heat and eventually raise the temperature, resulting in ‘urban heat islands’, he added.
“At the cost of native species”
Dr Hasan Jamil Kazmi, a professor at the University of Karachi’s Department of Geography, shared contrasting views about the Conocarpus tree. He apprised of the drawbacks of planting this exotic species, saying that it was an incorrect decision to grow this plant.
The plant was grown at the expense of the native species, he said, noting that the rationale behind the decision might have been its rapid growth but the tree comes with huge trimming cost as well.
He said that the plant’s roots grow horizontally so they absorb more water.
But at the same time, Dr Kazmi, who has researched extensively on the thermal emissions of Conocarpus and other native species, said the plant does not contribute to the rise in temperature.
We also asked former Karachi mayor Mustafa Kamal, who had overseen the planting of 2.2 million Conocarpus trees during his tenure, about the social media campaign against the species, but he said that he did not want to get involved in the matter.
Defending his decision, Kamal said the Conocarpus trees were planted keeping in mind Karachi’s environmental and economic betterment and the ground realities. He further said that researches supported the decision.