Essay on the Global Distribution of Important Species
Rangelands in western parts, the Tibet plateau and Australia are particularly rich in lizards and snakes adapted to arid conditions (Zhao and Adler, 1993). Rivers and freshwater lakes hold endemic species of fish and aquatic invertebrates (Kottelat and Whitten, 1996). Larger islands provide shelter to a wide range of endemic species.
Continental areas often have high species richness together with high rates of endemism. Such ‘hot spots’ can be identified at a range of scales, from individual mountains to extensive hill ranges. The entire Hindu Kush-Himalayan belt has 10 per cent of world’s flora with as many as 25,000 plant species (Shengji, 1998). A few such areas remain relatively unknown.
Large mammal species have recently been described in Vietnam and Laos. Biological resources have long been of subsistence importance, and have been increasingly exploited for trade. At global level, around three -qfiarters of known or suspected species extinctions have occurred on isolated islands (WCMC, 1992), mostly the molluscs and birds from the Asia Pacific region. Some 1469 vertebrate species are currently threatened with extinction.
Habitat loss is the principal factor that fragments natural populations and increases their risk of extinction but this often acts in synergy with pressures like, alien species and unsustainable harvesting (NBSAP, 2000).
2. Biodiversity in West Asia:
Wide variations in terrestrial and aquatic ecosystems include Mediterranean forests, rangelands and deserts exist. Marine ecosystems include mudflats, mangrove swamps, sea grass and coral reefs. Rivers in the Mashriq and springs in whole region represent freshwater ecosystems.
Estimated number of endemic vascular species is 800 (Batanouny, 1996), and in hot spots like Socotra Islands of Yemen, 34 per cent vascular plants are endemic, (Government of Yemen 2000). Seven endemic mammal species and ten endemic birds are reported (UNDP, UNEP, World Bank and WRI, 1998).
A total of 200 species of crabs, 20 species of marine mammals and more than 1,200 species of fish and 330 species of coral in the Red Sea and the Gulf are recorded (Fouda, Hermosa and Al-Harthi, 1998). More than 11 per cent of coral are endemic to the Arabian Peninsula sub-region (Shepard, Price and Roberts, 1992).
There are up to 12 000 marine species in the Mediterranean, representing 8-9 per cent of world sea species richness (Bianchi, Dore and Morri, 1995). Substantial number of vertebrates is threatened with extinction. Habitat destruction and fragmentation increased dramatically over the past three decades due to human populations and increased resources consumption.
Loss of genetic resources is the key biodiversity issues in West Asia. Water resource management and maintenance of inland water biodiversity as well as over hunting of large mammals and birds are the most important issues affecting biodiversity.
3. Biodiversity in Africa:
Five internationally recognized ‘biodiversity hot spots’ viz., Western Indian Ocean islands, the Cape floristic region, the Succulent Karoo (the most species rich desert in world), the Upper Guinea forest and the Eastern Arc mountain forests of Eastern Africa are found (Mittermeier and others, 2000).
Part of the Mediterranean Basin hotspot home to 25, 000 plant species and 14 endemic genera, are also found (Quezel and others, 1999). Several other areas of importance for biodiversity include highlands of Ethiopia; forests of the Albertine Rift in Burundi, eastern Congo, Rwanda and adjacent part of Kenya and Uganda; western escarpment of Angola; and miombo woodlands of interior Southern Africa (Mittermeier and others, 2000).
In the past three decades, habitat loss and degradation has been a major issue throughout Africa, particularly in dry land areas. In humid areas, bush meat trade hasclso had a significant impact on biodiversity. Biodiversity resources are extensively used for subsistence and commercial purposes.
Approximately 70 per cent of wild plant species in Northern Africa are used as source of traditional food, forage, medicine and agroforestry, and half have more than one use (WWF and IUCN, 1994).
Richness and diversity of ecosystems underpins a flourishing tourism industry, which is an important source of foreign exchange. Southern Africa’s wildlife attracted more than 9 million visitors in 1997, bringing in a total of US$ 4.1 billion (SADC, 2000).
4. Biodiversity in Europe:
Wide variety of ecosystems, ranging from the Atlantic coast to the Russian steppes and from boreal forest and tundra of Scandinavia to Mediterranean forests and shrub land is known (EEA, 2001).
Europe is also an important crossroads for migratory species shared with Africa, West Asia and North America. Agricultural land covers 45 per cent of Europe and most natural habitats are therefore restricted in extent. Agricultural impact on biodiversity is a key issue (Hoffmann, 2000).
Genetic modification of organisms for agriculture has also emerged as an important issue relating to biodiversity. Significant landscape modifications include deforestation, agriculture, drainage of wetlands, modifications to coastlines and river courses, mining, road construction and urban development. Reduced and fragmented natural habitats are less able to support wildlife.
Habitats like lowland forests and wetlands have undergone particularly large declines. Relatively pristine areas remain in some Nordic and Eastern European countries. Many large mammals, such as, polar bear (Ursus arctos), wolf (Canis lupus), lynx (Lynx-lynx) and bison (Bison bison bonasus) are now restricted to small remnants of their original habitats.
Tarpan (Equus caballus) and saiga (Saiga tatarica) have become extinct. Some 260 vertebrate species are now threatened with extinction in Europe. Lark (Alauda arensis) and hare (Lepus europaeus) are directly associated with agricultural landscapes, and have therefore benefited from human activities. Seagull (Larus spp.) and black kite (Milvus migrans) have increased in abundance due to growth in urban waste sites (EEA, 2001).
5. Biodiversity in Latin America and the Caribbean:
Wide variety of ecosystems including tropical moist and dry broadleaf forests covering 43% of territory, grasslands and savannas 40.5 %, deserts and scrub 11%, temperate forests and tropical and sub-tropical coniferous forests 5% and mangroves the remaining 0.5 % are recorded (Dinerstein and others, 1995).
Rivers, lake ecosystems and marine ecosystems of Pacific and Atlantic coasts are productive habitats with high species diversity. Caribbean contains 7% of world’s coral reefs (about 20 000 km2) with a great marine biodiversity (UNEP, 2001).
Seven of world’s 25 biologically richest terrestrial ecoregions are found in the regions, containing more than 46 000 vascular plants, 1,597 amphibians, 1,208 reptiles, 1,267 birds and 575 mammalian species (Myers and others, 2000) Glimpses of animal species diversity.