NCERT Solutions for Class 12 Biology BIODIVERSITY HOTSPOTS
Class 12 Biology: A biodiversity hotspot is a biogeographic region that has a significant pool of biodiversity but at the same time it is also threatened with destruction. The British biologist Norman Myers gave the term “biodiversity hotspot” in 1988. According to him, the biodiversity hotspot is a biogeographic region that has unique levels of plant endemism, along with serious levels of risk to the habitat.
The remaining natural habitat in these biodiversity hotspots amounts to just 1.4 percent of the land surface of the planet and supports nearly 60 percent of the world’s plant, bird, mammal, reptile, and amphibian species. Hot spots are the richest but most threatened reservoirs of plant and animal life of the earth. They have a maximum number of endemic species.
On our Earth, 35 areas qualify as Hotspots. They were once covering 15.7 percent of the Earth’s land surface. Today, 86 % of the hotspots’ habitat has already been destroyed, and thus, the intact remnants of the hotspots now occupy only 2.3 % of the Earth’s land surface. These Hotspots support more than half of the world’s plant species as endemics — i.e., species found no place else — and nearly 43% of bird, mammal, reptile and amphibian species as endemics.
25 terrestrial hot spots have been identified for the conservation of biodiversity. These hotspots occupy 1.4% of the earth’s surface and 20% of worlds the human population lives in these areas.
Parameters that define an area/region as a Biodiversity Hotspots are:
- Species endemism: The region must contain at least 1,500 species of vascular plants (> 0.5% of the world’s total) as endemics (The species that exist only in one geographic region).
- Degree of threat: Any region that has lost at least 70% of its original habitat is a Biodiversity Hotspot. Only 30% or less of its original natural vegetation exists
Each biodiversity hot spot represents an amazing universe of unusual floral and faunal endemism. These species struggle to survive in the rapidly vanishing ecosystems. Some hot spots are richer than others in terms of their numbers of endemics.
The eight hottest hotspots across the globe are:
- Sundaland in South East Asia
- Brazil’s Atlantic Forest
- The Western Ghats and Sri Lanka
- Eastern Arc and Coastal Forests of Tanzania/Kenya
BIODIVERSITY HOTSPOTS OF INDIA
There are 3 biodiversity hotspots present in India. They are:
- The Eastern Himalayas which includes: Arunachal Pradesh, Bhutan, Eastern Nepal
- Indo-Burma which covers Purvanchal Hills, Arakan Yoma, Eastern Bangladesh
- The Western Ghats and Sri Lanka
The Eastern Himalayas
The Eastern Himalayas is the region extending to Bhutan, north-eastern India, and southern, central, and eastern Nepal.
There is a lot of diversity of ecosystems in this region, which ranges from alluvial grasslands and subtropical broadleaf forests along the foothills to temperate broadleaf forests in the mid-hills, mixed conifer and conifer forests in the higher hills, and alpine meadows above the tree line.
Biodiversity of the Eastern Himalayas
The Eastern Himalayan hotspot has about 163 globally threatened species (both flora and fauna). Some species that are of serious concern are the One-horned Rhinoceros (Vulnerable), the Wild Asian Water buffalo (Endangered).
There are approximately 10,000 species of plants in the Himalayas, out of this one-third are endemic and found nowhere else in the world.
There are few threatened endemic bird species such as the Himalayan Quail, Cheer pheasant, are found here. There are also some of Asia’s largest and most endangered birds such as the Himalayan vulture and White-bellied Heron.
Some mammals like the Golden langur, Asiatic wild dogs, sloth bears, Sambar, Snow leopard, Black bear, Blue sheep, Takin, the Gangetic dolphin, wild water buffalo, swamp deer are found here.
The Indo-Burma region covers several countries.
It covers Eastern Bangladesh, Malaysia and includes North-Eastern India south of Brahmaputra river, Myanmar, the southern part of China’s Yunnan province, Lao People’s Democratic Republic, Cambodia, Vietnam, and Thailand.
There is a wide diversity of climate and habitat patterns in this region because of the vast area and several landforms.
Biodiversity of Indo-Burma Region
This region is home to several primate species such as monkeys, langurs, and gibbons with populations numbering only in the hundreds. Many of the species, like some freshwater turtle species, are endemic. Almost 1,300 bird species exist in this region like white-eared night-heron (Endangered), the Orange-necked partridge (a nearly threatened species). It is estimated that there are about 13,500 plant species in this hotspot, with over half of them endemic. Ginger, for example, is native to this region.
The Western Ghats and Sri Lanka
This region incorporates the mountain forests in the southwestern parts of India and highlands of southwestern Sri Lanka. The changes in the rainfall patterns in the Western Ghats, along with the region’s complex geography, produces a great variety of vegetation types. There are scrub forests in the low-lying rain shadow areas and the plains, deciduous and tropical rainforests up to about 1,500 meters, and entirely unique mountainous forests and rolling grasslands above 1,500 meters.
In Sri Lanka, diversity includes dry evergreen forests to dipterocarps dominated rainforests to the tropical montane cloud forest.
The important animal species include the Asian elephant, Indian tigers, lion-tailed macaque (all are endangered species), Indian Giant squirrel, etc.
Importance of Biodiversity Hotspots
The biodiversity hotspots are important because the habitats are highly susceptible to global changes and also due to high irreplaceability of species found within such a vast geographic region.
These hotspots are of social-cultural values, the richness of hotspot ecosystems offers essential ecosystem service.
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