Despite what you may imagine, large swathes of Sindh were once enriched with a wide variety of tree species but, over the years, the land has become denuded. Apparently, only two foreign species i.e. eucalyptus and conocarpus dominate regeneration programmes in the social and agro-forestry sectors.

In 2003, when the Sindh minister for local government and special development, Muhammad Hussain, had directed the authorities concerned to plant eucalyptus in parks and along roads to eliminate pollution. Environmentalists then too, had voiced their concerns about eucalyptus being unsuitable for the environment as it consumes large quantities of underground water, hence destroying growth of native species, causes asthma in humans and repels insects and birds because of its scent.

“Other than ornamental plants, eucalyptus and conocarpus have a high demand because they grow faster,” says Noor Muhammad Qambrani who runs a forest nursery at Tando Muhammad Khan.

But Nihal Khan Marri, an agricultural researcher disagrees. “Farmers are increasingly removing eucalyptus from their lands because on the one hand it takes up entire available water which results in reduced crop yield and on the other its fallen salt-rich leaves cause degradation of fertile soil.”

It’s ironic that a species which was introduced to reclaim degraded soil is now destroying fertile soils. Abid Hussain Rind, forester of Mirpurkhas endorses Marri’s view. “Earlier eucalyptus may have proved to be the most successful species, but now ruled out due to high water consumption and its timber being less useful because of fibre twist property.”

Learning no lessons from the previous disaster, the million-tree target of conocarpus plantation was initiated in 2009 by the City District Government Karachi and the species native to Africa and South America took Karachi by storm.

While the conocarpus plantation was in its initial stages, a scientific research was conducted by Karachi University botanists in 2010, which revealed that massive release of pollen from Conocarpus in the months of October and November can cause asthma and eczema among humans. The imported alien species depletes water and soil along with giving rise to pollen and seasonal allergies when transplanted in Karachi.

Why were exotic trees given preference over indigenous ones?

Dr Surayya Khatoon, Chairperson of the Botany department at Karachi University, sees it as a manifestation of an inferiority complex that our people seem to suffer from where they prefer imported things as opposed to local ones. The same, she says, is the case with trees.

Another factor could simply be the relative difficulty involved in harnessing local species. Dr Surayya commented, “Our horticulturists and foresters would have to collect their seeds from the wilderness, tend them carefully and they definitely take longer to grow. In their quest for faster growing plants, they opt for exotic species, which in an unfamiliar ecosystem dominate the other indigenous species which continue to grow at their normal pace.”

Presently, conocarpus is greening the areas around Shahrah-e-Faisal and Karsaz, Bin Qasim Park, Beach Park, DHA and University Road. It grows up to 20-40 feet and spreads around 15-20 feet in a short span and the bush-like appearance needs extensive trimming but can be groomed to an assortment of various shapes and sizes.

“It is a popular residential street tree; can successfully grow in urban areas where air pollution, poor drainage, compact and saline soil, and/or drought is common,” says Dr Tahir Qureshi at IUCN

However Dr Surayya points out that conocarpus is known for spreading pollen in the air in the same way as paper mulberry in Islamabad. “Studies show that it can cause severe respiratory tract diseases and allergic reactions in humans.”

But Tahir Qureshi has refuted the claim and says “no distinctive increase in allergy related disease has been noticed since the plant is vegetated for almost 10 years now.” Others believe that conocarpus releases some kind of chemical which hinders the growth of other variety of plants and trees, and also repels birds. “This also is just a rumor or controversy and needs more research to prove it” he added.

The unchecked assimilation of these two less eco-friendly species is clear indication that research in forestry sector in the Sindh is in doldrums. Although two major research institutes i.e. Miyani Research Station and Agricultural University are located in the close vicinity at Hyderabad, their scientifically proven research-oriented contribution in the forestry sector is yet to be seen.