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बेसिक इंग्लिश का दूसरा सत्र (कक्षा प्रारंभ : 22 अक्तूबर, शाम 3:30 से 5:30)
Jul 21, 2014

Biodiversity hotspots are areas that support natural ecosystems that are largely intact and where native species and communities associated with these ecosystems are well represented.  They are also areas with a high diversity of locally endemic species, which are species that are not found or are rarely found outside the hotspot. The concept of biodiversity hotspots was given by Norman Myers. Originally he gave  the twenty-five biodiversity hotspots (green, coded as 1-25) and later Nine hotspots (blue, 26-34) added by Mittermeier. (shown in diagram Below)

To qualify as a hotspot, a region must meet two strict criteria:

  1. It must contain at least 1,500 species of vascular plants (> 0.5 percent of the world’s total) as endemics.

  2. It has to have lost at least 70 percent of its original habitat.

Three factors that usually determine hotspots:

  1. The number of total species (species richness).

  2. The number of unique species (endemism).

  3. The number of species at risk (threat of extinction).

Some interesting hotspot facts:

  • 34 biodiversity hotspots have been identified.

  • They once covered 15.7 percent of the Earth’s land surface.

  • 86 % of the hotspots’ habitat has already been destroyed.

  • The intact remnants of the hotspots now cover only 2.3 % of the Earth’s land surface.

  • They contain 150,000 plant species as endemics, 50 %of the world’s total.

  • Terrestrial vertebrates endemic to the hotspots: 11,980, representing 42 percent of all terrestrial vertebrate species.

  • Reptiles and amphibians, are more prone to hotspot endemism than are the more wide-ranging mammals and birds, but the overall similarity between taxonomic groups is remarkable.

  • Overall, 22,022 terrestrial vertebrate species call the hotpots home, 77 percent of the world's total.

Management :

Hotspots are not formally recognised or governed areas. However, the identification of these areas as hotspots increases the likelihood of conservation investment. In addition, other designations for biodiversity conservation are likely to be present within these broad areas which may have more formal management structures. For example, the average protected area coverage of hotspots, based on IUCN protected area categories I-VI, is 10% of their original extent.

Indian Biodiversity Hotspot area :

A) Western Ghats (Sahyadri Hills): The Western Ghats, also known as the Sahyadri Hills , is a mountain chain running from the north to the South and is isolated by the Arabian Sea to the West, the arid Deccan Plateau to the East, and the Vindhya-Satpura ranges to the North. They have different vegetation types: scrub jungles and grasslands at low altitudes, dry and moist deciduous forests, montane grasslands and shoals, and the precious tropical evergreen and semi evergreen forests. Complex topography, high rainfall and relative inaccessibility have helped the region retain its biodiversity. Of the 15,000 flowering plant species in India, there are an estimated 4,780 species in the Western Ghats region. There is also a great diversity of traditional crop plants and an equal diversity of animal life. A large number of amphibians, freshwater fishes and invertebrate groups are endemic to Western Ghats.

There are a minimum of 6,000 vascular plant species in the Western Ghats and Sri Lanka hotspot, of which more than 3,000 (52 percent) are endemic. There are also more than 80 endemic plant genera, many of which have only one species.

In the Western Ghats, the Agasthyamalai Hills in the extreme south are believed to harbor the highest levels of plant diversity and endemism at the species level. Nearly 87 percent of the region’s flowering plants are found south of the Palghat Gap.

B) Indo-Burma (Eastern Himalayas ): The hotspot contains the Lower Mekong catchment. It begins in eastern Bangladesh and then extends across north-eastern India, south of the Bramaputra River, to encompass nearly all of Myanmar, part of southern and western Yunnan Province in China, all of the Lao People's Democratic Republic, Cambodia and Vietnam, the vast majority of Thailand and a small part of Peninsular Malaysia. In addition, the hotspot covers the coastal lowlands of southern China (in southern Guangxi and Guangdong), as well as several offshore islands, such as Hainan Island (of China) in the South China Sea and the Andaman Islands (of India) in the Andaman Sea. The hotspot contains the Lower Mekong catchment.

A wide diversity of ecosystems is represented in this hotspot, including mixed wet evergreen, dry evergreen, deciduous, and montane forests. There are also patches of scrublands and woodlands on karst limestone outcrops and, in some coastal areas, scattered heath forests. In addition, a wide variety of distinctive localized vegetation formations occur in Indo-Burma, including lowland floodplain swamps, mangroves, and seasonally inundated grasslands.

The patterns of biological diversity in Indo-Burma have resulted from the interaction of topography, past climate changes, soil characteristics, and the hotspot's patterns of seasonal rainfall. The hotspot contains many localized centers of endemism, particularly montane isolates, but also areas of lowland wet evergreen forest that were isolated at some stage, and river basins.

  • There are over 1,260 bird species found in Indo-Burma; more than 60 of these are endemic.

  • Gurney’s pitta (Pitta gurneyi, CR), a lowland evergreen forest bird endemic to Peninsular Thailand and adjacent parts of southern Myanmar, underwent a dramatic decline during the twentieth century due to extensive habitat loss.

  • There are about 430 mammal species in the hotspot; more than 70 species and seven genera are endemic. 

  • Indo-Burma also supports probably the highest diversity of freshwater turtles in the world: 53 species, representing one-fifth of the world's species.

  • Indo-Burma was one of the first places where humans developed agriculture, and has a long history of using fire to clear land for agriculture and other needs. The need for agricultural products has only increased in recent years, with the expansion of both human populations and markets. This has contributed to widespread forest destruction; tree plantations (teak, rubber, oil palm) have replaced large areas of lowland forest, while coffee, tea, vegetable crops and sugarcane plantations threaten montane and hill forests. Other threats to forests include logging, mining for gems and ore, firewood collection, and charcoal production.

  • Mangroves have been converted to shrimp aquacultural ponds, while intertidal mudflats have been extensively afforested with mangrove or intensely fished by lines of stack nets, which severely impacts their value as feeding habitat for migratory waterbirds and other species. Moreover, sand dune ecosystemsare severely threatened by afforestation, for instance, with the Australian exotic Casuarina equisetifolia. Finally, overfishing and the increasing use of destructive fishing techniques is a significant problem in both coastal and offshore marine ecosystems



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