Alien Invasive Species in Pakistan

The Problem

In Pakistan, any comprehensive cataloguing of alien species or any study on the magnitude or impacts of invasive species has not been done so far. According to a rough estimate, about 700 alien species of vascular plants are present in Pakistan, compared with about 4500 indigenous species (Khatoon & Ali, The Herald annual, January 1999). Of these 700 alien species, 5 or 6 could be recognized as high-impact invasives (viz. Broussonetia papyrifera, Prosopis juliflora, Eichhornia crassipes, Salvinia molesta, Parthenium hystrophorus, Lantana camara). Any comprehensive cataloguing (even of indigenous species) is not available about other organisms including animals, algae, fungi, bacteria, etc.; therefore anything could not be said with certainty about the number of alien species in these groups. The known intentional introductions of animal species include sheep and cow from Australia and New Zealand, fin and shellfish for aquaculture and aquaria, like silver carp, china grass carp, tilapia, rainbow trout etc., and Australian bees for apiculture. Of these introductions, tilapia has escaped aquaculture and has established on its own in many wetlands in Sindh (Q.M. Ali - personal communication), while China grass carp introduced in 1970's into Haleji Lake for controlling weeds has reportedly deprived the native herbivorous fish of their food. Accidental introductions include the insect pests of agriculture (e.g. American boll worm, Heliothis armigera) or horticulture.

Fortunately, the magnitude of alien species in Pakistan is not as great as aforementioned for some other countries; but unfortunately there is virtually no awareness on this important issue among general public, policy-makers, and even among most of forest department personnel. While most of the introduced plant species date back to colonial era, new intentional introductions (both authorized and unauthorized) are going unabated. Nursery-owners frequently import seeds and propagates of ornamental plants, while all the official tree-plantation drives involve alien species in most cases. The 1999 monsoon tree plantation drive in Sindh was launched by planting Lignum (Guaicum officinale - a native of S. America), while spring tree plantation of 2000 was launched by planting Eucalyptus. Back in 1998, a former Chief Minister had pledged to plant 8 million Eucalyptus trees in Sindh. In August 1999, an anti-pollutions rally organized by various government departments and NGOs planted 1000 saplings of Eucalyptus, neem, and Conocarpus around Keenjhar Lake to "save the lake" (DAWN Aug. 29, 1999). They do not know that they had actually damaged the lake surroundings by planting these alien species. Like Melaleuca, Eucalyptus is also capable of lowering water-table due to fast growth and excessive transpiration, besides having allelopathic effects on indigenous vegetation, and having highly inflammable volatile oil contents, which can trigger forest fires in hot and dry season. The large-scale introduction of Eucalyptus has not only changed the characteristic landscape of Sindh and many other parts of Pakistan, but in the long run it would show detrimental effects on water resources also. Both Eucalyptus and neem harbour fruit-eating bats, a potential serious threat to orchards, which actually serve as the seed-dispersal agents for the latter. Although these species have not so far become invasive, but may become so in future, given their large scale and repeated introduction coupled with targeted destruction of native vegetation in the name of "cleaning" the environment. The awareness campaigns on the importance of indigenous flora and the danger of alien species are needed in Pakistan more than anywhere else in the world.

Legislation/Prevention Measures

As such there is no legislation. The Biodiversity Action Plan (BAP) of Pakistan also dealt with this problem very superficially. The Action 6.6 of BAP reads: "Take measures to control invasive alien species of fauna and flora, and to prevent further introductions". The Quarantine Department checks the plant or animal species being imported only for any pests or pathogens accompanying it. There is no provision to check the possible ecological impact of the imported species per se.

National Efforts

The first-ever Workshop on the Invasive Species in Pakistan was held on Sept. 17, 1999 at NARC, Islamabad, jointly organized by IUCN and CABI-Bioscience (List of participants in Appendix-I). While discussing the issue, the participants agreed on following definition:

"Invasive species are those species which are alien, and which because of their aggressive and/or gregarious nature, become an agent of change, reducing the number, relative abundance and Importance Value Index (IVI) of the native species, and thereby threatening the overall biodiversity in a given region".

The participants also tried to prepare a list of more well-known invasive species (Appendix-II). Since comprehensive knowledge is hitherto available only for vascular plants (in the Flora of Pakistan), the Workshop deliberations were concerned with plants only; but it was decided that other groups would also be dealt with sometime later.

The Workshop recommended that an institution should be identified in the country to give certificate of clearance for introduction of species. This institution should be helped by a panel of experts belonging to various fields of biology, especially plant and animal taxonomists, and agriculturists and foresters, etc.

The Workshop also resolved to open the Pakistan Chapter of ISSG (Invasive Species Specialist Group) as ISSGP. The Invasive Species Specialists Group Pakistan has been formed at national level to look after the issues of invasives in the country. IUCN and CABI will support this group. This group, highlighting the problems created by the invasive species will produce a brochure. For awareness of public at large, stakeholders and policy makers ISSGP will issue newsletters, bulletins from time to time and identify the rising problems of aliens and invasive species in the country.