KARACHI: Planting trees along natural drains of Karachi wouldn’t only help reduce levels of toxic chemicals in sewage that ultimately falls into the sea and damage marine life, but would also have a profound positive impact on the city environment and health of its inhabitants, experts suggested on Wednesday.

They were speaking in connection with a recent tree plantation campaign initiated by the commissioner of Karachi in collaboration with the Sindh forest department and non-governmental organisations.

The target of the campaign was to plant 300,000 saplings on land owned by people or organisations ready to take care of the plantation.

Commenting on the effort, experts said that the government should look into the viability of planting trees along major drains in the city, including the Lyari and Malir Rivers.

“Such a plantation would not only partially address the problem of heavy metal-laden industrial waste going directly into the sea, but would also make the city greener, beautiful and healthy by increasing levels of oxygen and reducing carbon dioxide. The soothing effect the plantation would have on surrounding population is enormous,” said Prof Moinuddin Ahmed, an expert on dendrochronology (the study of climate change and past events by comparing the successive annual growth rings of trees or old timber).

Prof Ahmed, a visiting faculty member of the Federal Urdu University of Arts, Science and Technology currently working with a private company at Port Qasim, had submitted a tree plantation plan on similar lines to the city council (Karachi) about four years ago, but received no reply.

“Unlike developed countries, we have no laws that could discourage cutting of trees and bound people looking for commercial construction to grow maximum plants. Consequently, we are left with little green spaces,” he said.

A diverse range of plant species that, he said, were hardy, for instance, eucalyptus, neem, peepal, sheesham and banyan tree could be strategically grown in rows according to their capability to grow in a polluted area and public requirements.

“Once established, these trees that need to be planted in hundreds and thousands would appear like a forest. Some of these trees could be harvested on maturity, thus helping a town administration managing them to generate income,” Prof Ahmed added.

Seconding his opinion, Prof Tanveer Siddiqui, a senior botanist, said that the large area along the Lyari Expressway could be a good choice for such a plantation. “I think eucalyptus would be the best plant to be grown along drains. It’s easy to plant, grows fast and has a deep root system to absorb water,” he said.

Prof Abdul Hakeem Shaikh, former chairman of botany department, Urdu university now serving at Taibah University, Madina, Saudi Arabia, said that the idea was very much practical.

“The issue of heavy metals affecting food chain has become very serious in Pakistan and there is an immediate need to tackle it at every level. Growing non-edible plants and trees along major drains is one such option,” he said.

‘Measure requires thorough survey’

Tahir Qureshi, senior environmentalist working with the International Union for Conservation of Nature (IUCN) and former forest department official, said that tree plantation along natural drains required a thorough survey to look into the suitability of a particular drain spot for plantation.

“Drains have been widely encroached upon over the years and, then, they are blocked in many cases. Therefore, one has to do a detailed survey from the catchment area up to the sea to evaluate the viability of spots for planting a particular species and their future impact. Trees can’t be grown in pure sand, so there is a need to check soil conditions, too,” he explained.

According to Mr Qureshi, many thickly populated areas along the Lyari and Malir Rivers are suitable for plantation.

“There is a large area available for plantation in the Landhi-Korangi section of the Malir River. Besides, plantation can be done on Lyari River banks from upstream towards its mouth.

“Along with neem, peepal, conocarpus and eucalyptus, one can also grow Avicennia marina. Both eucalyptus and Avicenna marina have sweet fragrance that would help reduce the affect of sewage’s foul smell,” he said.

Mohammad Moazzam Khan, a marine expert at World Wide Fund for Nature-Pakistan, found the idea of planting trees along drains sound and said: “Plants have the ability to absorb some pollutants but can’t remove all contaminants. Tree plantation along drains is a good option as it would also serve as demarcation for the drain and a barrier to encroachment.”

Presently, he said, about 480 million gallons of sewage was generated in Karachi of which about 300MGD was disposed of through the Lyari River whereas the remaining was drained through the Malir River into the sea.

Most drains in the old city, according to Mr Khan, didn’t have space for plantation because of heavy encroachment. In newer city parts such as Gulshan-i-Iqbal and Gulistan-i-Jauhar, he believed, there was still space around drains that could be lined with suitable plants.

Experts like Farhan Anwar, an urban planner heading Sustainable Initiatives, a research and advocacy group focusing on issues related to urban sustainability, however, was unconvinced.

He said: “Although I am not a specialist in botany, the idea does not seem like a very sound planning solution to the problem of managing toxic liquid waste discharges. There are engineered solutions for linking plantation with sewage treatment such as designing an artificial wetland but, at least, I have not heard of just random plantation done to tackle such a problem. Then, chemical contents are really found in industrial wastes not municipal wastes where the solution has to be sewage treatment plants.”

Published in Dawn, October 9th, 2014