Loss of biodiversity

LOSS OF BIODIVERSITY

LOSS OF BIODIVERSITY The colonisation of tropical pacific islands by human beings has led to the extinction of more than two thousand species of native birds.The IUCN Red list (2004) document the extinction of 784 species in the last 500 that include 359 invertebrates, 338 vertebrates and 87 plants.Some of the animals that have become extinct recently include:

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STELLERS SEA COW (Russia)

DODO (Mauritius)

THYLACINE (Australia)

QUAGGA (Africa)

Three sub-species (BALI, JAVAN, CASPIAN) of TIGER

BALIJAVANCASPIAN

- More than 15,500 species worldwide are facing threat including 12 per cent of bird species, 23 per cent of all mammal species, 32 per cent of all amphibian species and 31 percent gymnosperm species.

- Before humans appeared on Earth, there have been five episodes of mass extinction (i.e., loss of large number of species in a short time), and Sixth Extinction presently in process.

- The current rate of species extinction is 100-1,000 times faster than the pre-human times and our activities are responsible for the faster rate.

Loss of biodiversity in a region can lead to the following:

(i) Decline in plant production

(ii) Lowered resistance to environmental perturbation.

(iii) Increased variability in ecosystem processes like water use, pest/disease cycles, plant productivity, etc.

CAUSES OF BIODIVERSITY LOSSES

There are four major causes (called The Evil Quartet) of biodiversity losses:

Habitat loss and fragmentation, over exploitation, alien species invasions and co-extinction.

HABITAT LOSS AND FRAGMENTATION

It is the most important cause of extinction, e.g.

The tropical rain forests, once covering 14 per cent of the land surface of Earth, but now they cover only 6 per cent of the land area.

The Amazon rain forests (called the lungs of the planet) are cleared for cultivation of soybeans or are converted into grasslands for raising beef-cattle.

The loss of a habitat deprives many animals and plants their homes and they face extinction.

Degradation of many habitats by pollution threatens the survival of many species.

When a large habitat is broken up into fragments, the populations of mammals and birds with migratory habits or requiring large territories are badly affected.

AMAZON RAIN FOREST (Lungs of the Planet)

OVER EXPLOITATION

When need turns to greed, it leads to over-exploitation of natural resources; many species become extinct, e.g.

Stellers sea cow, passenger pigeon, many marine fises became extinct due to over-exploitation by humans.

ALIEN SPECIES INVASION

When alien species are introduced in an area, some of them become invasive and may cause extinction of indigenous species, e.g.Introduction of Nile Perch into Lake Victoria (East Africa) caused extinction of more than 200 species of cichlid fish in lake.Invasive weed species such as Parthenium (carrot grass), Lantana and Eichhornia (water hyacinth) causing environmental damage and posing threat to our native species. The illegal introduction of the African catfish (Clarians gariepenus) for aquaculture purposes, is posing threat to the indigenous catfishes in our rivers.

CILCHID FISH

CARROT GRASS

LANTANAWATER HYACINTH

AFRICAN CAT FISH INDIGENOUS CAT FISH

CO-EXTINCTION

When a species becomes extinct, the plant and animal species associated with it also become extinct, e.g.

When a host fish becomes extinct, its unique parasites also become extinct.

Similarly, when one partner of a co-evolved pollitator mutualism becomes extinct, the other partner also have the same fate.

BIODIVERSITY CONSERVATION

REASONS FOR CONSERVATION OF BIODIVERSITY

The reasons of for conservation of biodiversity can be grouped into following three categories.

Narrowly utilitarian reasonsBroadly utilitarianEthical reasons

NARROWLY UTILITARIAN REASONS

These are obvious reasons.

Human being derive countless direct economic benefit from nature such as (cereals, pulse, fruits), firewood, fibre, construction materials, industrial products (tannin, lubricants, dyes, resins, perfumes) and products of medicinal importance.

More than 25 per cent of the drugs are derived from plants and about 25000 species of plants are used by native people as traditional medicine.

Now more and more resources are put into bioprospecting (i.e. exploring molecular genetic and species level diversity for products of economic importance) to know the economic use of plants.

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BROADLY UTILITARIAN

Biodiversity plays a major role in many ecosystem services provided by the nature. These include:

Production of oxygen e.g. Amazon forests produce 20 per cent of the total oxygen in the Earth atmosphere through photosynthesis.

(b) Pollination of plants (through bees, bumble bees, birds, and bats) without which they can not give us fruits and seeds.

(c) Aesthetics pleasures of walking through tick woods, watching spring flowers in full bloom, walking up to a bulbuls song in the morning etc.2

ETHICAL REASONS

Every species has an intrinsic value, even if it may not be of current economic value to us.

We have a moral duty to care for their well being and pass on the biological legacy in a good order to future generations. 3

CONSERVATION OF BIODIVERSITY

There are two approaches for conservation of biodiversity:

In situ conservation ( on site conservation)

Ex-situ conservation ( off site conservation) Biodiversity Conservation Strategies

In situ conservation Ex situ conservation

Biosphere reservesNational ParksWildlife sanctuariesSacred grovesBotanical GardensZoological ParksSeed BanksGene Banks

IN SITU CONSERVATION

Faced with the conflict between development and conservation, many nations find it unrealistic and economically not feasible to conserve all their biological wealth.The conservationists, have identified for maximum protection certain regions called biodiversity hotspots with high level of species richness and high degree of endemism (i.e., species confined to that region and not found anywhere else.)

Out of 34 hotspots of biodiversity in the world, three are in India, i.e. Western Ghats and Sri Lanka, Indo-Burma and Himalayas.

Biodiversity hotspots cover less than 2 per cent of the earths land area, they harbour extremely high number of species and strict protection of these hotspots could reduce the ongoing mass extinction by almost 30 per cent.

In India, ecologically unique and biodiversity rich regions are legally protected as:Biosphere ReservesNational ParksWildlife Sanctuaries andSacred Groves

BIOSPHERE RESERVES

These are large tracts of protected land with multiple use preserving the genetic diversity of representative ecosystem by protecting wildlife, traditional life styles of the tribals and varied plant and animal genetic resources.

India now has 14 biosphere reserves.

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NATIONAL PARKS

These are areas reserved for wildlife where they are able to obtain all the required natural resources and proper habitats.

Presently, India has 90 National Parks.2

WILDLIFE SANCTUARIES

These are tracts of land with or without lake where animals are protected from all types of exploitation and habitat disturbance.

At present, India has 448 wildlife sanctuaries.

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SACRED GROVES

These are tracts of forest set aside where all the trees and wildlife within are venerated and given total protection.

Such sacred groves are found in Khasi and Jaintia Hills in Meghalaya; Aravali Hills of Rajasthan; Western Ghat regions of Karnataka and Maharashtra and the Sarguja; Chanda and Bastar area of Madhya Pradesh.

In Meghalaya, the sacred groves are the last refuges for a large number of rare and threatened plants.4

SACRED GROVEAsacred groveorsacred woodsare anygroveof trees of special religious importance to a particular culture. Sacred groves feature in various cultures throughout the world.

EX SITU CONSERVATION

The threatened animals and plants are taken out from their natural habitat and placed in special setting, where they can be protected and given special care.

Botanical gardens, zoological parks and wildlife safari parks serve this purpose.

The gametes of threatened species are preserved in viable and fertile conditions using cryopreservation techniques.

Commercially important plants can be kept for long periods using tissue culture methods or in seed banks.

Ex situ conservation has following disadvantages:Some plants do not produce fertile seeds.

Loss of seed viability.

Seed destruction by pests, etc.

Poor germination rate.

This is only useful for seed propagating plants.

Its a costly process.

INTERNATIONAL EFFORTS FOR BIODIVERSITY CONSERVATION

THE EARTH SUMMIT

It was the historic convention on Biological diversity, held in Rio de Janeiro in 1992.

It called upon all the nations to take appropriate measures for Conservation of biodiversity, andSustainable utilization of the benefits of biodiversity.

THE WORLD SUMMIT

It was held in 2002 in Johannesburg, South Africa.

190 countries pledged their commitment to achieve a significant reduction in the current rate of biodiversity loss at global, regional and local levels by 2010.

Thank You.