Biodiversity

• Biodiversity or biological diversity is the variation among living

organisms on the scale of genes, species, ecosystems, both terrestrial
and aquatic in a defined area.
• The degree of nature’s variety in biosphere.

• Ecosystem

• Specific

• Genetic
• Genetic Diversity-
• It is the basic source of biodiversity
• The genes found in organisms can form enormous number of
combinations each of which gives rise to some variability
• Genes are the basic units of hereditary information transmitted
from one generation to other
• When the genes within the same species show different versions
due to new combinations, it is called genetic variability
• For example, all rice varieties belong to the species Oryza sativa,
but there are thousands of wild and cultivated varieties of rice
which show variations at the genetic level and differ in their color,
size, shape, aroma and nutrient content of the grain. This is the
genetic diversity of rice.
• Species Diversity-
• This is the variability found within the population of a species or
between different species of a community
• It represents broadly the species richness and their abundance in a
community
• There are two popular indices of measuring species diversity known as
Shannon-Wiener index and Simpson index
• What is the number of species on this biosphere?
• Issues of data deficiency and unavailability
• The current estimates given by Wilson in 1992 put the total number of
living species in a range of 10 million to 50 million
• Till now only about 1.5 million living and 300,000 fossil species have
been actually described and given scientific names
• It is quite likely that a large fraction of these species may become extinct
even before they are discovered and enlisted
• Ecosystem Diversity-
• This is the diversity of ecological complexity showing variations in ecological
niches, trophic structure, food-webs, nutrient cycling etc.
• The ecosystems also show variations with respect to physical parameters
like moisture, temperature, altitude, precipitation etc. Thus, there occurs
tremendous diversity within the ecosystems, along these gradients
• Example- forest ecosystem: while considering a tropical rainforest, a tropical
deciduous forest, a temperate deciduous forest and a boreal forest, the
variations observed are just too many and they are mainly due to variations in
the above mentioned physical factors.
• This diversity has developed over millions of years of evolution and destruction
would disrupt the ecological balance
• Coniferous trees of boreal forests cannot take up the function of the trees of
tropical deciduous forest lands and vice versa, because ecosystem diversity has
evolved with respect to the prevailing environmental conditions with well
regulated ecological balance
Biogeographic zones of India
• India's biogeographic classification is a division of the country based
on biogeographic characteristics
• India has a rich heritage of natural diversity
• Among the top 17 megadiverse countries in the world, India ranks
fourth in Asia and tenth globally
• The study of the distribution of species (biology), organisms, and
ecosystems in geographical space and over geological time is known
as biogeography
• India has ten biogeographical zones.
• Trans Himalayan-
• It accounts for 5.6% of the total geographical area and includes the
high altitude, cold and arid mountain areas of Ladakh, Jammu and
Kashmir, North Sikkim, Lahaul and Spiti areas of Himachal Pradesh.
• This zone has sparse alpine steppe vegetation that supports several
endemic species and is a suitable habitat for the world's largest
populations of wild sheep and goats, as well as other rare fauna such
as the Snow Leopard and the migratory Blacknecked Crane (Grus
nigricollis).
• This zone's cold, dry desert is an extremely vulnerable ecosystem.
• Himalayan-
• It accounts for 6.4% of the total geographical area and contains some
of the highest peaks in the world.
• The Himalayan zone makes India one of the richest areas in terms of
habitats and species.
• Location: East, northwest, west, and central Himalayas
• The alpine and subalpine forests, grassy meadows, and moist mixed
deciduous forests provide diverse habitat for endangered bovid
species such as Bharal (Pseudois nayaur), Ibex (Capra ibex), Markhor
(Capra falconeri), Himalayan Tahr (Hemitragus jemlabicus), and Takin
(Budoreas taxicolor).
• Other rare and endangered species restricted to this zone include
Hangul (Cervus eldi eldi) and Musk Deer (Moschus moschiferus).
• Desert/Arid zone-
• The extremely arid region west of the Aravalli hill range, which includes
both Gujarat's salty desert and Rajasthan's sand desert.
• The Indian desert forms India's northern boundary, encompassing primarily
the western and northwestern regions of Rajasthan, as well as a portion of
the Kachchh region of Gujarat in the southwest.
• It is 350-450 metres above sea level in the east at the Aravalli range, 100
metres in the south and west, and 20 metres in the Rann of Kachchh.
• It has large expanses of grassland that support several endangered species
of mammals such as Wolf (Canis lupus), Caracal (Felis caracal), Desert Cat
(Felis libyca), and birds of conservation interest such as Houbara Bustard
(Chamydotis undulate) and the Great Indian Bustard (Ardeotis nigriceps).
• Semi Arid zone-
• The semi-arid region, which accounts for 16.6% of the total geographical area, is a transition
zone between the desert and the dense forests of the Western Ghats.
• Peninsular India has two large semi-arid regions. This semi-arid region also has several artificial and
natural lakes, as well as marshy lands.
• The dominant grass and palatable shrub layer in this zone supports the most wildlife biomass.
• The area is distinguished by discontinuous vegetation blanketed with bare soil and soil water that is
in short supply all year.
• This zone includes the Punjab plains, Delhi, Haryana, Jammu and Kashmir's fringes, Himachal
Pradesh's western edges, eastern Rajasthan, eastern Gujarat, and northwest Madhya Pradesh.
• In Western India, the Semi-arid zone is characterised by savannah woodland, dry deciduous forest,
and tropical thorn forest.
• The heart of this zone is the Aravalli System, which is home to two types of vegetation: tropical dry
deciduous forest and tropical thorn forest.
• The cervid species Sambar (Cervus unicolor) and Chital (Axis axis) are restricted to better wooded
hills and moister valley areas, respectively.
• The Lion (Panthera leo persica), an endangered carnivore species (restricted to a small area in
Gujarat), Caracal (Felis caracal), Jackal (Canis aureus), and Wolf (Canis lupus) are among the
endangered species found in this region.
• Western Ghats-
• The Western Ghats accounts for 4% of the total geographical area.
• It is one of India's major tropical evergreen forest regions and one of two biodiversity 'hot spots.
• The Western Ghats run along the west coast of peninsular India from the Tapti river in the north to
Kanyakumari in the south, passing through the states of Gujarat, Maharashtra, Goa, Karnataka, Tamil
Nadu, and Kerala.
• The Western Ghats zone is one of the world's 25 biodiversity 'hotspots' and one of India's major tropical
evergreen forested regions, with enormous plant diversity.
• The region is home to nearly 4000 species of flowering plants, accounting for nearly 27% of India's total
flora. 1500 of these species are endemic.
• The Western Ghats region is a significant genetic estate with a diverse array of ancient lineages.
• The Western Ghats are home to viable populations of most of the vertebrate species found in peninsular
India, as well as an endemic faunal element.
• Nilgiri Langur (Presbytis jobni), Lion Tailed Macaque (Macaca silenus), Grizzled Giant Squirrel (Ratufa
macroura), Malabar Civet (Viverricula megaspila), Nilgiri Tahr (Hemitragus bylocrius), and Malabar Grey
Hornbill (Ocycerous griseus) are all endemic to this region.
• The Travancore Tortoise (Indotestudo forstem) and Cane Turtle (Heosemys silvatica) are two endangered
species found only in a small area of the central Western Ghats
• Deccan Plateau-
• The Deccan Plateau is India's largest biogeographic region, accounting for 42% of the total
geographical area.
• It is a semi-arid region located in the rain shadow of the Western Ghats.
• The zone is relatively homogeneous, with climates ranging from semi-arid to moist-
deciduous/semi-evergreen.
• This bio-geographic zone of peninsular India is by far the most extensive, covering India's finest
forests, particularly in the states of Madhya Pradesh, Maharashtra, and Odisha.
• The Vindhya and Satpura hill ranges, the Chhota Nagpur Plateau, the Eastern Ghats, the Tamil
Nadu Plains, and the Karnataka Plateau are all part of the central highlands. The Vindhya and
Satpura hill ranges are famous for their diverse flora.
• The majority of the forests are deciduous, but there are areas of greater biological diversity in the
hill ranges. The zone, which includes deciduous forests, thorn forests, and degraded scrubland, is
home to a variety of wildlife species.
• Species found in this region include:
• Chital (Axis axis), Sambar (Cervus unicolor), Nilgai (Boselapbus tragocamelus), Chousingha
(Tetracerus quadricornis), Barking deer (Muntiacus muntjak), Gaur (Antilope cervicapra),
Elephant (Elephas maximus) in Bihar-Orissa and Karnataka-Tamil Nadu belts.
• Wild Buffalo (Bubalus bubalis) in a small area near the border of Orissa, Madhya Pradesh, and
Maharashtra.
• The hard ground Swamp Deer (Cervus duvauceli), which is now restricted to a single locality in
Madhya Pradesh.
• The Gangetic Plains-
• The Gangetic plain accounts for about 10.8 percent of the total geographical
area. The Gangetic plain is topographically homogeneous for hundreds of
kilometers.
• The Gangetic divide, the Upper Gangetic plain, the Middle Gangetic plain, and
the Lower Gangetic plain are all part of this zone.
• This zone, which stretches from eastern Rajasthan through Uttar Pradesh to
Bihar and West Bengal, is mostly agricultural and has a dense human
population.
• The Gangetic plain encompasses the Terai-Bhabar tracts of Uttar Pradesh,
Bihar, and West Bengal.
• Teak, shisham, sal, khair, and other trees from these forests have some of the
highest population densities and topographic uniformity.
• This region's fauna includes the Rhinoceros unicornis, Elephant (Elephas
maximus), Buffalo (Bubalus bubalis), Swamp Deer (Cervus duvauceli), Hog-Deer
(Axis porcinus), and Hispid Hare (Carprolagus bispidus).
• North East India-
• The North East Region accounts for 5.2 percent of the total
geographical area.
• This region is a transition zone between the Indian, Indo-Malayan,
and Indo-Chinese bio-geographical regions, as well as a meeting point
for the Himalayan mountains and peninsular India.
• The North-East is thus a biogeographical 'gateway' for much of India's
fauna and flora, as well as a biodiversity hotspot (Eastern Himalaya).
• Many of the species that contribute to this biological diversity are
either restricted to the region itself or to smaller localised areas of the
Khasi Hills.
• Islands-
• This zone, which accounts for 0.3% of India's total geographical area, is one of
the three tropical moist evergreen forest zones.
• The islands are home to unique flora and fauna. These islands are high endemism
hotspots, with some of India's finest evergreen forests and a diverse range of
corals.
• The islands are divided into two major groups: the Lakshadweep Islands and the
Andaman Islands.
• The Lakshadweep Islands are a group of 27 small islands located in the Arabian
Sea. They are 320 kilometres from Kerala's coast.
• The Andaman and Nicobar Islands are a 348-island group in the Bay of Bengal
that runs north-south.
• The Andaman Islands are about 190 kilometres from the nearest point on the
mainland, Cape Negrais in Burma.
• The Great Andaman (300 km long) is made up of five islands that are close
together, with the Little Andaman to the south.
• The Nicobar groups of islands are separated from the Andamans and from one
another by 800 m deep channels.
• In India, only the Andaman and Nicobar Islands have endemic island
biodiversity. Some of the endemic fauna of the Andaman and Nicobar
islands include the Narcondam hornbill and the South Andaman
krait.
• The Lakshadweep is made up of 25 coral islets with a typical reef
lagoon system rich in biodiversity. However, the densely populated
Lakshadweep islands have almost no natural vegetation.

• Coastal-
• The coastal region accounts for 2.5 percent of total geographical
area, and its sandy beaches, mangroves, mud flats, coral reefs, and
marine angiosperm pastures make it India's wealth and health zone.
• The coastline from Gujarat to the Sunderbans is estimated to be
5,423 kilometers long.
• Loss of Species and Biomass: Human activities are responsible for the majority of
threats to species, sites, and habitats.
• Changes in Climatic Conditions: When a forest is cut and burned to make way for
cropland and pastures, the carbon stored in the tree trunks combines with
oxygen and is released into the atmosphere as CO2. This amplifies the
greenhouse effect and contributes to rising global temperatures.
• Drying up of rivers and aquifers: Rivers and aquifers are drying up as a result of
increased forest removal. Reduced rainfall reduces the percolation of water in the
underground, lowering the levels of the underground water-table.
• Floods and Droughts: As CO2 levels rise in the atmosphere, temperatures rise,
resulting in floods and droughts. Water evaporates quickly as a result of the high
temperature. Eroded soil that lacks vegetative cover cannot retain moisture for
long. As a result, this causes droughts.
• Desertification: The continuous expansion of deserts into previously semi-arid
regions is a serious manifestation of the long-term effects of land degradation
and intensive soil erosion.
• Rapid melting of glaciers: This is a result of global warming, which is depleting
the sources of fresh water for our rivers and streams that flow from the
Himalayan ranges.