Factors affecting biodiversity in Pakistan

The biggest threat to biodiversity is the loss of its natural habitat. In Pakistan the continuous and progressive loss, fragmentation and degradation of natural habitats is leading to the disappearance of countless species. The forest area is already fragmented and degraded and is being subjected to further destruction, as are most rangelands and freshwater and marine ecosystems. There is concern for the ongoing decline of many native species of animals and plants; some of which are already extinct. Agro-ecosystems are also fast disappearing and there is accelerated loss of domesticated genetic diversity. This loss has been more rapid in the past few decades. The trend is apparent in the remaining upland forests, scrub forests, mangrove forests, arid and semi-arid rangelands (including sand-dune deserts), inland wetlands, the Indus Delta, and coastal waters.

Critically threatened Ecosystems

Biodiversity Action Plan 1998 – Biodiversity guide to Pakistan

The biodiversity of the country is fast heading towards complete annihilation. The loss is due to direct as well as indirect (root) causes.

Activities leading to habitat loss

According to UNEP 1995:

"loss of habitats is the principal cause of the present high rate of global extinction, and poses a severe threat in all biomes "

Contrary to the misconception that 'safe' habitat loss does not affect biodiversity, all levels of habitat destruction trigger the risk of local extinction of some species. Although some reserves do provide a safe haven for certain species, no network of carefully selected and well managed sanctuaries and reserves would suffice to protect all species. Even subtle changes in habitat quality while less grave than habitat loss, affect plant and animal populations. When habitats become fragmented the risk of extinction increases because previously more connected populations become isolated into small pockets. These pockets are more vulnerable to loss of genetic variability and run a higher risk of extinction.

Deforestation

Large tracts of forest are cut down for the timber trade. Trees are indiscriminately cut to provide for the ever-increasing demand for timber, without any consideration for the environment or the age of the tree. Consumption of fuelwood also takes place unchecked in Pakistan, as a large portion of the population relies on this for heat.

Grazing and fodder collection

The rapidly increasing domestic livestock population is also taking its toll on the country's rangelands and forests. The numbers of cattle have almost doubled between 1945 and 1986 (GOP/JRC 1992), while the number of goats, and sheep almost tripled and the numbers continue to increase at the rate of 2% per year. Although a large part of the livestock population is fed by the production of fodder in irrigated areas, overgrazing by livestock allowed to roam free, has reduced forage production in the rangelands to one-third of its potential (loss of almost 50 million tonnes annually). In certain areas, particularly in Balochistan it is as low as 15% of the potential (GOP/JRC 1992), .

Soil Erosion

When the vegetation cover is depleted, wind and water erosion is exacerbated. Because of the mountainious terrain in the NWFP and the Northern Areas water erosion creates major problems. Erosion affects 11 million hectares of the country and around 45 million tonnes of soil are eroded annually. This leads to sedimentation of wetlands and the subsequent habitat degradation.

Even though wind erosion is not as great a concern as water erosion, the additional loss of precious topsoil has a diverse impact. Around 2 million hectares of the country are going through moderate or severe erosion. Among these, the light soils of the Potwar Plateau and the sandy soils of the Thar and Cholistan deserts are especially vulnerable to wind erosion. Soil erosion means the loss of organisms, plant diversity and the population of animals supported by the plants.

Water diversion and drainage

Since a large part of the country is irrigated much of its water is diverted for irrigation. The total water that flows from the river Indus and its tributaries is 139 maf annually. Of the total surface irrigation water, 110 maf is diverted to canals.(Dawn)

Water is also drained out of small wetlands created by the irrigation systems, for agricultural use. Falling of groundwater levels, caused by draining the water and discharge of saline water into the wetland is also a threat.

Intensity of agriculture and livestock breeding

Irrigation can result in increased salinity and waterlogging, causing the degradation of agro-ecosystems. Salinity affects 5.7 million hectares in Pakistan (Dawn). Most of the soil affected is of low agricultural potential, however almost 10% of good soil is also affected.

The introduction and spread of high yielding varieties (HYV) is the principal cause of the loss of crop genetic diversity. The HYVs are responsive to water and fertiliser but pose a huge threat to indigenous plants.

Crossbreeding in lifestock can bring rapid gains in productivity but it also increases the rate of loss of genetic purity if the parental stock is not maintained. Around 75-80% of Pakistan's stock is crossbreeds.(Biodiversity Action plan pg-12)

The introduction of exotic species is also a problem. Although the magnitude of the problem is not exactly known in the country, a number of fast growing tree species and exotic fish are posing a serious threat to the local varieties.

Activities leading to species loss

Human Use of Wildlife in Pakistan