Table of Contents
- Biodiversity is the variety of plant and animal life in the world or in a particular habitat.
Measurement of Biodiversity
- Biodiversity is measured by two major components:
- species richness, and
- species evenness.
- It is the measure of number of species found in a community
- It refers to the diversity within a particular area or ecosystem, and is usually expressed by the number of species (i.e., species richness) in that ecosystem.
- It is a comparison of diversity between ecosystems, usually measured as the change in amount of species between the ecosystems.
- It is a measure of the overall diversity for the different ecosystems within a region.
- It measures the proportion of species at a given site, e.g. low evenness indicates that a few species dominate the site.
- Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species.
- A single species might show high diversity at the genetic level [E.g. Man: Chinese, Indian American, African etc.]. India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango.
- Genetic diversity allows species to adapt to changing environments. This diversity aims to ensure that some species survive drastic changes and thus carry on desirable genes.
- It is the ratio of one species population over total number of organisms across all species in the given biome. ‘Zero’ would be infinite diversity, and ‘one’ represents only one species present.
- Species diversity is a measure of the diversity within an ecological community that incorporates both species richness (the number of species in a community) and the evenness of species.
- For example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats. There are more than 200000 species in India of which several are confined to India (endemic).
- Endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. A particular type of animal or plant may be endemic to a zone, a state or a country. The extreme opposite of endemism is cosmopolitan distribution.
- Species differ from one another, markedly in their genetic makeup, do not inter-breed in nature. Closely-related species however have in common much of their hereditary characteristics. For instance, about 98.4 per cent of the genes of humans and chimpanzees are the same.
- According to the IUCN (2004), the total number of plant and animal species described so far is slightly more than 1.5 million, but we have no clear idea of how many species are yet to be discovered and described. A large proportion of the species waiting to be discovered are in the tropics. Estimate place the global species diversity at about 7 million.
- More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total.
- Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total. That means, out of every 10 animals on this planet, 7 are insects.
- The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles and mammals.
- It should be noted that these estimates do not give any figures for prokaryotes. Biologists are not sure about how many prokaryotic species there might be.
- In general, species diversity decreases as we move away from the equator towards the poles. With very few exceptions, tropics (latitudinal range of 23.5° N to 23.5° S) harbour more species than temperate or polar areas.
- India, with much of its land area in the tropical latitudes, has more than 1,200 species of birds.
- The largely tropical Amazonian rain forest in South America has the greatest biodiversity on earth- it is home to more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of reptiles and of more than 1,25,000 invertebrates.
- Speciation is generally a function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification.
- Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialization and lead to a greater species diversity.
- There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.
- For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with less species.
- What exactly is stability for a biological community? A stable community should not show too much variation in productivity from year to year; it must be either resistant or resilient to occasional disturbances (natural or man-made), and it must also be resistant to invasions by alien species.
- Although, we may not understand completely how species richness contributes to the well-being of an ecosystem, we know enough to realize that rich biodiversity is not only essential for ecosystem health but imperative for the very survival of the human race on this planet.
Bioprospecting: nations endowed with rich biodiversity explore molecular, genetic and species-level diversity to derive products of economic importance.
- Ecological diversity refers to the different types of habitats. A habitat is the cumulative factor of the climate, vegetation and geography of a region.
- It includes various biological zones, like lake, desert, coast, estuaries, wetlands, mangroves, coral reefs etc.
- At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.
- Ecosystem services.
- Protection of water resources.
- Soils formation and protection.
- Nutrient storage and recycling.
- Pollution breakdown and absorption.
- Contribution to climate stability.
- Maintenance of ecosystems.
- Recovery from unpredictable events.
- Food and shelter.
- Medicinal resources.
- Wood products.
- Ornamental plants.
- Breeding stocks, population reservoirs.
- Future resources.
- Diversity in genes, species and ecosystems.
- Research, education and monitoring.
- Recreation and tourism.
- Cultural values.
Biodiversity of India
- India is a recognized as one of the mega-diverse countries, rich in biodiversity and associated traditional knowledge.
- India has 23.39% of its geographical area under forest and tree cover.
- With just 2.4% of the land area, India accounts for nearly 7% of the recorded species even while supporting almost 18% of human population.
- In terms of species richness, India ranks seventh in mammals, ninth in birds and fifth in reptiles.
- In terms of endemism of vertebrate groups, India’s position is tenth in birds with 69 species, fifth in reptiles with 156 species and seventh in amphibians with 110 species.
- India’s share of crops is 44% as compared to the world average of 11%.
- Two ‘Realms’
- Five Biomes
- Ten Bio-geographic Zones
- Twenty five Bio-geographic provinces
- Biogeographic realms are large spatial regions within which ecosystems share a broadly similar biota.
- Realm is a continent or sub-continent sized area with unifying features of geography and fauna & flora.
- The Indian region is composed of two realms. They are:
- the Himalayan region represented by Palearctic Realm and
- the rest of the sub-continent represented by Malayan Realm
- In world Eight terrestrial biogeographic realms are typically recognized. They are
- Nearctic Realm
- Palaearctic Realm
- Africotropical Realm
- Indomalayan Realm
- Ocenaia Realm
- Australian Realm
- Antarctic Realm
- Neotropical Realm
- The term biome means the main groups of plants and animals living in areas of certain climate patterns.
- It includes the way in which animals, vegetation and soil interact together. The plants and animals of that area have adapted to that environment.
The five biomes of India are:
- Tropical Humid Forests
- Tropical Dry or Deciduous Forests (including Monsoon Forests)
- Warm deserts and semi-deserts
- Coniferous forests and
- Alpine meadows.
- Biogeography deals with the geographical distribution of plants and animals.
- Biogeographic zones were used as a basis for planning wildlife protected areas in India.
- There are 10 biogeographic zones which are distinguished clearly in India. They are as follows:
- An extension of the Tibetan plateau, harboring high-altitude cold desert in Laddakh (J&K) and Lahaul Spiti (H.P) comprising 5.7 % of the country’s landmass.
- The entire mountain chain running from north-western to northeastern India, comprising a diverse range of biotic provinces and biomes, 7.2 % of the country’s landmass.
- The extremely arid area west of the Aravalli hill range, comprising both the salty desert of Gujarat and the sand desert of Rajasthan. 6.9% of the country’s landmass.
- The zone between the desert and the Deccan plateau, including the Aravalli hill range. 15.6 % of the country’s landmass.
- The hill ranges and plains running along the western coastline, south of the Tapti river, covering an extremely diverse range of biotic provinces and biomes. 5.8% of the country’s landmass.
- The largest of the zones, covering much of the southern and southcentral plateau with a predominantly deciduous vegetation. 4.3 % of the country’s landmass.
- Defined by the Ganges river system, these plains are relatively homogenous. 11% of the country’s landmass.
- The plains and non-Himalayan hill ranges of northeastern India, with a wide variation of vegetation. 5.2% of the country’s landmass.
- The Andaman and Nicobar Islands in the Bay of Bengal, with a highly diverse set of biomes. 0.03% of the country’s landmass.
- A large coastline distributed both to the west and east, with distinct differences between the two; Lakshadweep islands are included in this with the percent area being negligible.
- Bio-geographic Province is a ecosystematic or biotic subdivision of realms. India is divided into 25 bio geographic zones.
Biogeographic Zones (10)
Biogeographic Provinces (25)
|1.||Trans Himalaya||1A: Himalaya – Ladakh Mountains|
1B: Himalaya – Tibetan Plateau
1C: Trans – Himalaya Sikkim
|2.||The Himalaya||2A: Himalaya – North West Himalaya|
2B: Himalaya – West Himalaya
2C: Himalaya – Central Himalaya
2D: Himalaya – East Himalaya
|3.||The Indian Desert||3A: Desert – Thar|
3B: Desert – Katchchh
|4.||The Semi-Arid||4A: Semi – Arid – Punjab Plains|
4B: Semi – Arid – Gujarat Rajputana
|5.||The Western Ghats||5A: Western Ghats - Malabar Plains|
5B: Western Ghats – Western Ghats Mountains
|6.||The Deccan Peninsula||6A: Deccan Peninsular – Central Highlands|
6B: Deccan Peninsular – Chotta Nagpur
6C: Deccan Peninsular - Eastern Highlands
6D: Deccan Peninsular – Central Plateau
6E: Deccan Peninsular - Deccan South
|7.||The Gangetic Plains||7A: Gangetic Plain - Upper Gangetic Plains|
7B: Gangetic Plain – Lower Gangetic Plains
|8.||The Coasts||8A: Coasts – West Coast|
8B: Coasts – East Coast
8C: Coasts – Lakshadweep
|9.||Northeast India||9A: North – East – Brahmaputra Valley|
9B: North – East – North East Hills
|10.||Islands||10A: Islands – Andaman|
10B: Islands – Nicobars
- The west Himalayas have low rainfall, heavy snowfall (temperate conditions), whereas in east Himalayas, there is heavy rainfall, snowfall only at very high altitudes, whereas at lower altitudes conditions are similar to the tropical rain forests. Flora and fauna of both Himalayas differ.
- Flora: Natural monsoon evergreen and semi-evergreen forests; dominant species are sal, silk-cotton trees, giant bamboos; tall grassy meadow with savannahs in terai.
- Fauna: Includes big mammals of like elephant, sambar, swamp deer, cheetal, hog deer, barking deer, wild boar tiger, panther, hyena, black bear, sloth bear, Great Indian one-horned rhinoceros, wild buffalo, Gangetic gharial, golden langur.
[Some of these which are threatened are explained in the next post: Red Data Book]
- Flora: Natural monsoon evergreen and semi-evergreen forests; rhododendrons; dwarf hill bamboo and birch forests mixed with alpine pastures.
- Fauna: Tibetan wild ass (kiang) [Don’t confuse this with Asiatic wild ass which in found in Kutch region], wild goats (thar, ibex) and blue sheep; antelopes (Chiru and Tibetan gazelle), deers (hangul of Kashmir stag and shou or Sikkim stag, musk deer); golden eagle, snow cocks, snow partridges; snow leopard, black and brown bears; birds like Griffon vultures.
What is the difference between the antelopes Oryx and Chiru?
- Oryx is adapted to live in hot and arid areas whereas Chiru is adapted to live in steppes and semi-desert areas of cold high mountains. .
- Oryx is poached for its antlers whereas Chiru is poached for its musk.
- Oryx exists in western India only whereas Chiru exists in north-east India only.
- None of the statements a, b, and c given above is correct.
They are both antelopes.
- Flora: Oaks, magnolias, laurels and birches covered with moss and ferns; coniferous forests of pine, fir, yew and junipers with undergrowth of scrubby rhododendrons and dwarf bamboos; lichens, mosses, orchids, and other epiphytes dominant (due to high humidity and high rainfall).
- Fauna: Red panda, hog badgers, forest badgers, crestless porcupines, takins etc.
- It has two zones.
- peninsular India and its extension into the drainage basin of the Ganges river system, and
- desert region of Rajasthan-the Thar of Indian desert region.
- It is home to tropical moist deciduous to tropical dry deciduous and scrub vegetation depending upon the variation in rainfall and humidity.
- Flora: Sal in north and east extensions (higher rainfall) and teak in southern plateau are dominant trees.
- West Ghats have evergreen vegetation (flora and fauna similar to evergreen rainforests of north eastern of India. In dry areas of Rajasthan and Aravalli hills, trees are scattered and thorny scrub species predominate. The forests give way to more open savannah habit.
- Fauna: Elephant, wild boar, deers (cheetal or axis deer), hog deer swamp deer or barasinga, sambar, muntjak or barking deer, antelopes (four-hourned antelope, nilgiri, blackbuck, chinkara gazelle), wild dog or dhole, tiger, leopard, cheetah, lion, wild pig, monkey, striped hyena, jackal, gaur.
- Thar desert of Rajasthan has unique flora and fauna.
- Flora: Thorny trees with reduced leaves; cacti, other succulents are the main plants.
- Fauna: Animals are mostly burrowing ones. Among mammals rodents are the largest group. The Indian desert gerbils are mouse like, rodents, other animals are, Asiatic wild ass, black buck, desert cat, caracal, red fox; reptiles (snackes, lizards and tortoise) well represented. Desert lizards include agamids, and geckos. Among birds the most discussed is Great Indian bustard.
- Distributed in areas of western Ghats and north east India.
- Flora: Extensive grass lands interspersed with densely forested gorges of evergreen vegetation known as sholas occur in the Nilgiris (an offshoot of Western Ghats). Sholas also occur in Anamalai and Palani hills.
- The rain forests of the Western Ghats have dense and lofty trees with much species diversity. Mosses, ferns, epiphytes, orchids, lianas and vines, herbs, shrubs make diverse habitat. Ebony trees predominate in these forests.
- Fauna: It is very rich with all kinds of animals. There are wild elephants, gaur and other larger animals. Most species are tree dwellers. The most prominent are hoolock gibbon (only ape found in India), golden langur, capped langur or leaf monkey, Assam macaque and the pig-tailed macaque, lion-tailed macaque, Nilgiri langur slender loris, bats, gaint squirrel, civets, flying squirrels, Nilgiri mongoose, spiny mouse.
- Flora: These are home for tropical rain forests. Mangroves are distributed in the coastal areas.
- Fauna: Among mammals, bats and rats; Andaman pig, crab-eating macaque, palm civet and deers (spotted deer, barking deer, hog deer, sambar).
- Among marine mammals there are dugong, false killer whale, dolphin.
- Among birds are rare one is Narcondum hornbill, white-bellied sea-eagle.
- Salt-water crocodile, a number of marine turtles, coconut crab, lizards (the largest being water monitor), 40 species of snakes including cobra, viper, voral and sea snake, python, etc. are present.
- Sunderbans are delta of the Ganges where both the Brahmaputra and Ganges join and drain into the Bay of Bengal.
- Flora: Various species of mangroves.
- Fauna. In the higher regions of mangroves, there are spotted deer, pigs, monitor lizard, monkeys. The most interesting animal of Sunderbans is the Royal Bengal Tiger.