Superabundance of non eco-friendly trees in Dhaka city: Study

The number of trees in the capital city of Dhaka are decreasing day by day. Along with this wetlands are also shrinking. Less trees are being planted against the number of trees felling every year.

Though the two city corporations of Dhaka, Department of Environment and Department of Roads and Highways (RHD) have planted some trees, most of them are of foreign and invasive species. There are also plans to plant tamarisk trees.

Beautification is getting more importance than considerationsof whether the trees are harmonious with Dhaka’s environment or not. As a result, these trees are not helping to reduce the temperature in Dhaka.

But in the red soil of Dhaka, species of trees like sal, chalta and sundari could grow well. Though those trees are more harmonious with the environment too, no one has planted a single tree of these species in Dhaka in the last decade. There is no plan either to plant those trees in the future.

Naturalists and botanists say that though the heatwaves are sweeping across the country, its effect in the capital is very high. They stressed that in the case of planting trees in Dhaka, whether it is compatible with the local environment or not must be considered.

Last December, a study was conducted on the diversity of plants in Dhaka city under the leadership of professor Mohammad Zashim Uddin of Botany Department at Dhaka University.

The study, conducted in Ramna Park, Suhrawardy Udyan and Dhaka University area, revealed that 58 per cent of the trees in these areas are foreign species. Of those plants, 33 per cent have the purpose of beautification only.

A visit on Wednesday showed a row of bonsai on both sides of the airport road in Dhaka. These trees have been planted from Nikunja to Hotel Radisson.

The Roads and Highways Department brought these trees from China and Taiwan to beautify the city in 2017. However, the work of planting these expensive trees did not proceed further due to strong opposition from environmentalists and botanists.

A visit from Bijoy Sarani to Karwan Bazar showed that there are bougainvilleas and a few other shrubs planted in plastic baskets on the sides of overbridges. Those were planted under the Clean Air and Sustainable Environment (CASE) project of the Department of Environment in 2010 with a view to improve the air quality. But that did not happen.

The CASE project ended in the face of huge criticisms. Even the then president of the parliamentary committee on environment ministry spoke to the media about irregularities in the project in 2019.

Apart from this, most of the trees planted by the Dhaka North City Corporation in the half-a-kilometre stretch road divider from Bijoy Sarani to Farmgate police box under a project were Chinese pinwheel flower, jungle geranium and bougainvillea.

Project director Md Nuruzzaman said a total of 90,000 trees have been planted under the project, with 80 per cent of them on the road dividers. chatim (blackboard tree), almond trees and bakul flowers were planted on the footpaths, with each costing about Tk 1,500-1,700.

The consultants of the project created a handbook titled ‘Handbook on street planting: Prepared for Dhaka North City Corporation’ is rife with mistakes. But the main thing is the trees selected for planting in the capital city.

Professor Mohammad Zashim Uddin of Botany Department at Dhaka University told Prothom Alo, “How could they plant several foreign species of trees and those suitable for charlands?”

Sal trees are the most suitable kind of tree for Dhaka that has red clay.

Soil Resource Development Institute’s principal scientific officer Md Afsar Ali told Prothom Alo even today you would get red clay if you dig just 10-feet in Dhaka. Consequently, Sal and the similar kind of trees could be a better choice for this city.

Dhaka South City Corporation planted 5,000 trees in the last year, claimed supervisor engineer (environment, climate and disaster management circle) Md Khairul Baker.

Botanists and naturalists talked about planting different types of trees at different areas of the capital city. He was asked whether they considered this.

Khairul Baker said, “We have employed an expert and have been going ahead according to a plan.”

But not only the two city corporations, this correspondent did not find any plan for planting trees at large government and private buildings. There should be a guideline for this, thinks architect Meherun Farzana, who works on greening the urban and industrial areas.

She said new buildings have been constructed in the Agargaon area; many trees were felled as the roads there have been widened. But you don’t see any greenery in the buildings.

Botanists said trees with large leaves and branches should be planted in cities as those could exhaust carbon dioxide fast.

Professor Rakha Hari Sarker of Botany Department at Dhaka University once said, “There are hundreds of species of trees in the Dhaka region that we could use for decreasing heat. But it does not seem the city corporations have been selecting the trees taking advice from the botanists.”

Bangladesh Institute of Planners (BIP) general secretary Sheikh Mohammad Mehedi Ahsan in one of his researches has shown that the percentage of trees in Dhaka has come down from 20 per cent to a mere 9 per cent in the last three decades while the 21 per cent water body has decreased to just 3 per cent.

Professor Mohammad Zashim Uddin of Botany Department at Dhaka University led a study on the diversity of plants in Dhaka city.

The study was conducted in Ramna Park, Suhrawardy Udyan and Dhaka University area. It found that 58 per cent of the trees in these areas are of foreign species. Of those plants, 33 per cent have the purpose of beautification only.

A research report published in the Bangladesh Journal of Plant Taxonomy in 2021 showed that out of the 15 species of trees planted on road dividers, nine were invasive foreign species.

Professor Mohammad Zashim Uddin termed this choice of invasive foreign species of trees over the local species as suicidal. This will have a far reaching consequence, he warned.

* This report, originally published in Prothom Alo’s print and online editions, has been rewritten in English by Shameem Reza