Biodiversity hotspot

Also called: Hotspot · Topic: Biodiversity and its Conservation · NCERT: Class 11, Ch 14 "Biodiversity and Conservation"

Meaning

A biodiversity hotspot is a region that has a very large number of endemic species (species found naturally in that one region and nowhere else) and that has also lost most of its natural habitat. To be called a hotspot, a region must have at least 1,500 endemic vascular plants and must have lost at least 70% of its original habitat [8].

Hotspots matter because conservation money is limited. The 36 hotspots cover only about 2.5% of the Earth's land, but they hold more than half of the world's endemic plant species. So protecting them saves the most species for each rupee spent.

Explanation

Who gave the idea and who set the rules

• Norman Myers, a British ecologist, first proposed the idea of hotspots in 1988.
• Conservation International set the formal criteria in Myers et al., Nature, 2000 ("Biodiversity hotspots for conservation priorities") [8].
• NCERT trap: NCERT says IUCN identified the hotspots. This is a common mistake. The criteria come from Myers and Conservation International, not from IUCN.

The two criteria (a region must meet both)

Criterion	Threshold	What it measures
Irreplaceability	At least 1,500 endemic vascular plants, which is more than 0.5% of the world's total	How unique the region is
Threat	At least 70% of the original habitat lost, so 30% or less of the natural vegetation is left [8]	How much danger the region is in

• Vascular plants are plants with tubes that carry water and food, such as ferns and flowering plants.
• A region rich in endemic species but still mostly untouched is not a hotspot.
• A badly damaged region with few endemic species is not a hotspot either.

Why plants are used to define hotspots

• Plants are the primary producers:
• They turn sunlight into food. This is called primary productivity.
• Every animal in the ecosystem depends on this food, directly or indirectly.
• So a region with many endemic plants usually has many endemic animals too.

How hotspots form: cause → process → result

• Warmth and rain all year (mostly in the tropics):
• Strong sunlight and steady rain let plants grow all year.
• This gives animals many niches (different ways of living).

• The result is a very large number of species.

• Isolation:

• Islands such as Madagascar and the Nicobar Islands, and separate hill ranges such as the southern Western Ghats, keep species apart.
• Each group evolves on its own and becomes different from the others.

• The result is high endemism.

• Human pressure:

• Forests are cleared for farms, firewood, mining and towns. On islands like Hawaii, people also bring in introduced species (plants and animals carried from other places) that compete with native species or eat them.
• Endemic species have nowhere else to go, so they die out.
• This pushes the region past the 70% habitat-loss line.

Where it occurs

World

• There are 36 hotspots. The latest one, the Forests of East Australia, was added in 2016.
• Madagascar: an island in the Indian Ocean, off the south-east coast of Africa.
• About 85% of its plants and animals are found nowhere else. Lemurs are the best-known example.
• The island broke away from the mainland millions of years ago, so its species evolved in isolation.

• Threat: forests are cleared for food, firewood and farmland.

• Hawaii: volcanic islands in the central Pacific Ocean. The main threats are introduced species and development (towns, tourism and farms).

India: parts of 4 of the 36 hotspots [2]

Hotspot	Indian part	Extends to
Himalaya	The whole Indian Himalaya	Nepal, Bhutan and neighbouring countries
Indo-Burma	North-east India (east of the Brahmaputra)	Myanmar, Thailand and Indochina
Western Ghats and Sri Lanka	Western Ghats (Sahyadri)	Sri Lanka
Sundaland	Nicobar Islands only	Malay Peninsula and the islands of Indonesia

• Endemism in Indian hotspots: in the Eastern Himalaya and the Western Ghats, 32–40% of vascular plants are endemic. In the Western Ghats, more than 50% of reptile, amphibian and fish species are endemic [3].
• Western Ghats:
• They run from the Tapi river in the north to Kanyakumari in the south.
• They pass through Gujarat, Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu.
• The highest peak is Anamudi (2,695 m) in the Anaimalai Hills of Kerala.
• Why they are so rich: the south-west monsoon wind hits the Ghats and is pushed up. The rising air cools and brings very heavy rain to the side facing the wind (the windward side). This rain supports wet evergreen forests.
• They hold about 30% of India's biodiversity [4].
• Endemic species: the Nilgiri tahr, the lion-tailed macaque, the Malabar civet and Humboldtia decurrens.

• They became a UNESCO World Heritage Site in 2012 under natural criteria (ix) and (x), with 39 component sites in 7 sub-clusters [6][7].

• Indira Point (about 6°45′N), the southern tip of Great Nicobar, lies inside the Sundaland hotspot.

Don't confuse with

• Megadiverse country: this is a whole country with a very large share of the world's species. NCERT lists 12 and Conservation International (1998) lists 17. There is no habitat-loss rule. A hotspot is a region that can cross borders, and it must meet both the endemism rule and the threat rule.
• Endemic species vs. endangered species: an endemic species is found in only one region. An endangered species is at risk of dying out. A hotspot needs both: many endemic plants and heavy habitat loss.
• IUCN Red List: this is IUCN's list of threatened species. The hotspot criteria come from Myers and Conservation International, not from IUCN.
• UNESCO World Heritage Site (natural): this is a legal listing of particular protected areas, such as the 39 Western Ghats components. A hotspot is a scientific priority region with no legal protection of its own.

Prelims Hooks

• Hotspot criteria: at least 1,500 endemic vascular plants AND at least 70% of original habitat lost. A region must meet both, not just one [8].
• The concept came from Norman Myers (1988). The criteria were set by Conservation International (Myers et al., 2000), not IUCN.
• There are 36 hotspots. The 36th, the Forests of East Australia, was added in 2016. Together they cover about 2.5% of land and hold more than half of all endemic plants.
• India's 4 hotspots are the Himalaya, Indo-Burma, Western Ghats and Sri Lanka, and Sundaland [2]. The Eastern Ghats are not a hotspot.
• Trap: only the Nicobar Islands are in Sundaland, and Indira Point lies in it. The Andaman Islands are not.
• Pairs: Lemur → Madagascar; Nilgiri tahr, lion-tailed macaque, Humboldtia decurrens → Western Ghats; introduced species → Hawaii.

Mains Points

• Why hotspots cluster where they do (GS-I):
• Heat and rain all year in the tropics give high primary productivity, which supports many species.
• Isolation on islands (Madagascar, Nicobar) and on separate hill ranges (southern Western Ghats) lets species evolve apart, which gives high endemism.

• Heavy human pressure in these same regions turns species-rich areas into threatened hotspots.

• Hotspots as a way to set priorities, and their limits (GS-III):

• Strength: they cover about 2.5% of land but hold more than half of all endemic plants, so scarce conservation money goes where it saves the most species.

• Weakness: the method counts only plants. It can miss areas rich in animals or marine life, and dry lands such as grasslands and deserts.

• Western Ghats: conservation vs. development (GS-III):

• Mining, quarrying, plantations, hydro projects and roads are breaking the forest into pieces.
• The Gadgil panel (WGEEP, 2011) recommended wide, graded Ecologically Sensitive Areas (ESAs: zones where mining, quarrying and some building are limited). The Kasturirangan group (HLWG, 2013) proposed a smaller ESA [4]. The Environment Ministry then issued directions on 13 November 2013 under the Environment (Protection) Act, 1986 [5].
• The final ESA notification is still contested by the states over development, mining and the rights of local people. This shows the clash between protecting nature and meeting livelihood needs.

Related concepts

• Megadiverse countries
• Madagascar hotspot
• Biodiversity hotspots in India
• Western Ghats and Sri Lanka hotspot

Read more

• Megadiversity countries and biodiversity hotspots