$\displaystyle \small \bullet$ There are many reasons, which explain the essentiality of conservation of biodiversity.
$\displaystyle \small \bullet$ These reasons can be broadly grouped into three categories: narrow utilitarian, broad utilitarian and ethical reasons.

Narrowly Utilitarian Reasons
$\displaystyle \small \bullet$ Human derive economic benefits from nature such as food, firewood, fibre, construction material, industrial products(tannins, lubricants, dyes, resins, perfumes) and medicines.  
$\displaystyle \small \bullet$ More than 25% of the drugs are derived from plants.
$\displaystyle \small \bullet$ 25,000 species of plants have medicinal value.  
$\displaystyle \small \bullet$ In tropical rain forests there are number of medicinally useful plants, such plants are not known and they are waiting to be explored.

Broadly Utilitarian Arguments
$\displaystyle \small \bullet$ Biodiversity has many ecosystem services.
$\displaystyle \small \bullet$ E.g. Amazon forest (‘lung of  the planet’ ) produces 20% of total $\displaystyle O_{2}$ in the earth’s atmosphere.
$\displaystyle \small \bullet$ Pollination through bees, bumblebees, birds and bats.  
$\displaystyle \small \bullet$ Aesthetic pleasures.

Ethical Arguments  
$\displaystyle \small \bullet$ Every species has an intrinsic value. We have a moral duty to care for their well-being.

Methods of Biodiversity Conservation
a. In situ (on site) conservation
b. Ex situ (off site) conservation.

In situ conservation (on site)
$\displaystyle \small \bullet$ It is the conservation of genetic resources within natural or human-made ecosystems in which they occur.
$\displaystyle \small \bullet$ E.g. Protected areas such as National Parks, Sanctuaries, Biosphere reserves, cultural landscapes, natural monuments etc.  
$\displaystyle \small \bullet$ National Park: Strictly reserved for the welfare of the wildlife where private ownership, cultivation, grazing etc are prohibited.
$\displaystyle \small \bullet$ Sanctuary: Here, protection is given only to the animals. Collection of timbers, minor forest products and private ownership are allowed so long as they do not harm the animals.
$\displaystyle \small \bullet$ Biosphere Reserves: Areas of land or coastal ecosystems for conservation and sustainable use.
$\displaystyle \small \bullet$ Sacred forests (Sacred groves): E.g.
 $\displaystyle \small \circ$ Sacred groves in Khasi & Jaintia Hills in Meghalaya
 $\displaystyle \small \circ$ Aravalli Hills of Rajasthan
 $\displaystyle \small \circ$ Western Ghat regions of Karnataka & Maharashtra  
 $\displaystyle \small \circ$ Sarguja, Chanda & Bastar areas (Madhya Pradesh).
$\displaystyle \small \bullet$ India has 14 Biosphere Reserves, 90 National Parks and 448 wildlife sanctuaries.   
$\displaystyle \small \bullet$ Biodiversity hotspots: the regions with very high levels of species richness and high degree of endemism are called biodiversity hotspots.
$\displaystyle \small \bullet$ Endemism or endemic species: species confined to that particular region and not in found any other regions.
$\displaystyle \small \bullet$ These hotspots are also regions of accelerated habitat loss. Three of these hotspots are – Western Ghats and Sri Lanka, Indo-Burma and Himalaya – cover our country’s exceptionally high biodiversity regions.
$\displaystyle \small \bullet$ Although all the biodiversity hotspots put together cover less than 2% of the earth’s land area, the number of species they collectively harbor is extremely high and strict protection of these hotspots could reduce the ongoing mass extinctions by almost 30%.

Ex situ conservation (off site)
$\displaystyle \small \bullet$ It is the conservation of organisms outside their habitats.
$\displaystyle \small \bullet$ E.g. genetic resource centres, zoological parks, wildlife safari parks,botanical gardens, gene banks, cryopreservation etc.  
$\displaystyle \small \bullet$ There are many animals that have become extinct in the wild but continue to be maintained in zoological parks.
$\displaystyle \small \bullet$ In recent years ex situ conservation has advanced beyond keeping threatened species in enclosures.
$\displaystyle \small \bullet$ Now gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques (preservation at –1960C).
$\displaystyle \small \bullet$ Eggs can be fertilized in vitro, and plants can be propagated using tissue culture methods.
$\displaystyle \small \bullet$ Seeds of different genetic strains of commercially important plants can be kept for long periods in seed banks.

$\displaystyle \small \bullet$ For Biodiversity there are no political boundaries and its conservation is a collective responsibility of all nations.
$\displaystyle \small \bullet$ The historic Convention on Biological Diversity (‘The Earth Summit’) held in Rio de Janeiro in 1992, called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilization of its benefits.
$\displaystyle \small \bullet$ The World Summit on Sustainable Development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010, a significant reduction in the current rate of biodiversity loss at global, regional and local levels
$\displaystyle \small \bullet$ The International Union for Conservation of Nature (IUCN), created the IUCN Red List of Threatened Species in 1964 – a system for classifying species according to the risk of extinction they face.

Biological Status Description of Status
Least Concern (LC) Widespread and not in imminent danger of being threatened.
Near Threatened (NT) A species that could in the near future be placed in a ‘threatened’ category (below).
Vulnerable (VU) Facing a high risk of extinction in the wild.
Endangered (EN) A species that’s facing a very high risk of extinction in the wild.
Critically Endangered (CR) Facing an extremely high risk of extinction in the wild.
Extinct In The Wild (EW) No longer found in the wild. Populations are only found in zoos, botanical gardens or breeding programmes.
Extinct (EX) No individuals exist in the wild, in captivity or cultivation.