VPE 511: Environment and Environmental Hygiene (2+1)

THREATS TO BIODIVERSITY

• Though the rate of loss of species has been a slow process in the past, the process of extinction has become fast in recent years. It has been reported that approximately 10,000 species become extinct every year. This raises an alarm regarding the threat to biodiversity. IF this trend continues 1/3 or 2/3 of our current biodiversity would become extinct by the middle of the 21^st century.

Factors causing loss of biodiversity

• Loss of Habitat
• Destruction of habitats due to clearing of forests and grasslands for agricultural lands, pastures, settlement areas or project development lead to loss of habitat. These factors are responsible for the disappearance of thousands of species. According to the world Health Organisation (WHO) estimates, about 80% of the population of developing countries relies on traditional medicines, mostly drugs from plants. In order to meet the demand, about 86% of plant collection involves destructive harvesting. Many plants become endangered, besides loss and degradation of natural habitats take place due to overharvesting.
• The wetlands, mangroves and estuaries with rich biodiversity are under threat. They are destroyed, as if they have no value. For example estuarine ecosystem in Adyar, Chennai has disappeared posing a major treat to nearly 170 species of birds, many of which nest and breed there. Tropical forests disappear at the rate of 0.6% per year in our country. Marine biodiversity is also threatened by human intervention.
• The wetlands in India are distributed in different geographical regions. Most of the wetlands in India are linked with major river systems. India has 27403 wetlands covering 4.1 million . Of these , 2,175 are natural and the rest are manmade. Wetlands occupy 18.4 of the area of our country of which 70% are under rice cultivation. In India, out of an estimated 4.1 million ha of wetlands, 1.5 mha are natural and 2.6 mha are man-made. Wetlands provide food and shelter for mammals and birds.
• Poaching of wild life
• The illegal commercial hunting is called poaching. There are two types of hunting subsistence hunting (killing animals for food) and sport hunting (killing animals to sell their meat, fur, horns, tusks etc.)
• Man-Animal conflicts
• Sometimes, wild animals threaten human beings. This leads to conflict between wild life and man. For example elephant in Sambalpur, Orissa killed 195 humans in 5 years. The villagers killed 98 elephants in retaliation and injured 30 elephants.

Causes

• When the habitats of wild animal are destroyed by man, the animals are forced to come out of the forest in search of food to the nearby human settlements and attack human beings when they come in contact with them accidentally.
• When rice, sugarcane , etc., are not cultivated within the sanctuaries, the animals move out in search of food. One adult elephant needs 2 quintals of green fodder and 150 litres of water daily. If this is not available, the wild animals move out.
• The weak and injured animals have a tendency to attack man. A tigress attacks man in order to protect its cubs. Once a tiger tastes the flesh of a man accidentally, it becomes a man-eater.
• When wildlife corridors are converted into human settlements, the path of wild life is disrupted and animals attack the settlements.
• Since the compensation by the government in lieu of crop damage is not enough, the agonized farmers kill the wild animal to protect their crops.