Biodiversity
Definition
'Biological
diversity' means the variability among living organisms from all sources including, inter
alia, terrestrial, marine and other aquatic ecosystems and the ecological
complexes of which they are a part; this includes diversity within species,
between species and of ecosystems. The variety of life
at every hierarchical level and spatial scale of biological organizations:
genes within populations, populations within species, species within
communities, communities within landscapes, landscapes within biomes, and
biomes within the biosphere.
Global Biodiversity
Gradient
Biodiversity is not
distributed evenly across the planet: Biodiversity is not
distributed evenly across the planet but shows a rather uneven distribution, certain ecosystems and regions contain far more species than others.
Tropical rain forests, coral reefs, the deep sea, and large tropical lakes
appear to be the most species rich ecosystems on the planet (WCMC 1992; Heywood
1995; Levin 2001). For most groups of terrestrial plants and animals, species
diversity is lowest near the poles and increases toward the tropics, reaching
its peak in tropical rain forests. These forests, occupying only 6 percent of
the earth’s land surface, are believed to contain more than half the species on
earth.
Biodiversity in Indian context
India has
only 2.4 per cent of the world’s land area, its share of the global species
diversity is an impressive 8.1 per cent. That is what makes our country one of
the 12 mega diversity countries of the world. Nearly 45,000 species of plants
and twice as many of animals have been recorded from India. How many living
species are actually there waiting to be discovered and named? If we accept
May’s global estimates, only 22 per cent of the total species have been
recorded so far. Applying this proportion to India’s diversity figures, we
estimate that there are probably more than 1,00,000 plant species and more than
3,00, 000 animal species yet to be discovered and described. Would we ever be
able to complete the inventory of the biological wealth of our country?
Consider the immense trained manpower (taxonomists) and the time required to
complete the job. The situation appears more hopeless when we realise that a
large fraction of these species faces the threat of becoming extinct even
before we discover them. Nature’s biological library is burning even before we
catalogued the titles of all the books stocked there.
Biodiversity in the
international context
Biodiversity is
defined as the “variability among living organisms from all sources, including,
inter alia, terrestrial, marine, and other aquatic ecosystems, and the
ecological complexes of which they are part: this includes diversity within
species, between species and of ecosystems” (CBD, 1992). The three ultimate
objectives of the 1992 UN Convention on Biological Diversity (CBD) are:
- the conservation of biological diversity;
- the sustainable use of its components;
- the fair and equitable sharing of the benefits arising out of the utilization of genetic resources.
In 2002, parties to
the CBD adopted a strategic plan “to achieve by 2010 a significant reduction of
the current rate of biodiversity loss at the global, regional and national
level as a contribution to poverty alleviation and to the benefit of all life
on Earth” (the 2010 target; Decision VI/26). This target was subsequently
endorsed by the World Summit on Sustainable Development and incorporated as a
target under the Millennium Development Goals. It is widely acknowledged
however, that the 2010 biodiversity target was not met. Recognising the
importance of this global environment problem, the United Nations General
Assembly declared 2011-20 the United Nations Decade on Biodiversity. The tenth
meeting of the Conference of Parties (COP-10) to the CBD in 2010, held in
Nagoya, Japan, led to the successful agreement on a revised Strategic Plan for
Biodiversity 2011-2020 and the Aichi Biodiversity Targets. In addition, Parties
adopted a Strategy for Resource Mobilisation, a consolidated list of guidance
to the financial mechanism, and an international regime for Access and Benefits
Sharing (i.e. for the equitable sharing of the benefits arising out of the
utilisation of genetic resources). CBD COP-11 in October 2012, in Hyderabad,
India focused on addressing implementation issues and established, for example,
an indicator framework to monitor progress on the implementation of the Aichi
Biodiversity Targets and the Strategy for Resource Mobilisation. The OECD’s
analysis supports the work of the CBD.
Evolution of
Biodiversity
Biodiversity is a
product of the numerous biological and geophysical events that have occurred
over the history of life on Earth.
- Life on Earth is 3.7 - 3.85x109 years old
- Evolutionary history shapes contemporary physical and biological environment
- Current diversity of species is a product of the processes of extinction and speciation
Extinction
Extinction is an
important part of the process of evolution of biodiversity and does not occur
at a constant pace. It is the complete disappearance of a species from Earth.
Thus, extinction is the final and irreversible event of species loss. In
contrast, extirpation is the local or regional
disappearance of a species from only a part of its range. There have been at
least five periods when there was a sudden increase in the rate of extinction –
to at least double – affecting many different types of plants and animals.
Levels of
biodiversity
Biodiversity is
commonly considered at three different levels:
- Within species (intraspecific) diversity; usually measured in terms of genetic differences between individuals or populations.
- Species (interspecific) diversity, measured as a combination of number and evenness of abundance of species.
- Community or ecosystem diversity, measured as the number of different species assemblages.
Biodiversity,
therefore, is usually considered at three hierarchical levels i.e. Genetic,
Species and Community and Ecosystem levels.
1. Genetic
diversity
Genetic diversity
refers to any variation in the nucleotides, genes, chromosomes, or whole genomes of organisms. This is the “fundamental currency of
diversity” (Williams and Humphries, 1996) and the basis for
all other organismal diversity. Genetic diversity is the sum total of genetic
information, contained in the genes of individuals of plants, animals and
microorganisms that inhabit the earth. It is needed by any species in order to
maintain reproductive vitality, resistance to disease and the
ability to adapt to changing conditions. It enables a
population to adapt to its environment and to respond to natural selection. The amount of
genetic variation is the basis of speciation. Genetic diversity within a
species often increases with environmental variability. Such genetic
variability has made it possible to produce new breed of crops plants and domestic animals, and in the world allowed species to adapt to changing conditions.
2. Species
diversity:
- A group of organisms genetically so similar, that they can interbreed and produce fertile off springs is called a species.
- The species diversity is usually measured in terms of the total number of species within discrete geographical boundaries.
- Species diversity -
“species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups”
(Mayr 1963)
- Species are distinct units of diversity each playing a specific role in the ecosystem.
- In nature, both the number and kind of species, as well as the number of individuals per species vary, leading to greater diversity. The different sample areas showing species richness (sample area 1), Species evenness (sample area 2) and diversity due to taxonomically unrelated species (sample area 3).
It is defined by
the species that occupy a particular locality and the interactions between
them. It represents the collective response of species to different
environmental conditions. Biological communities such as deserts, grasslands,
wetlands, and forest support the continuity of proper ecosystem functioning by
providing ecological beneficial services to people.
Diversity at the
level of community and ecosystem exists along 3 levels.
- It could be within-community diversity (alpha diversity), between-communities diversity (beta diversity) or
- diversity of the habitats over the total landscape or geographical area (gamma diversity).
Alpha, Beta, and
Gamma Diversity
Whittaker (1972)
described three terms for measuring biodiversity over spatial scales: alpha,
beta, and gamma diversity.
- Alpha Diversity : 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.
- Beta diversity : a comparison of diversity between ecosystems, usually measured as the amount of species change between the ecosystems.
- Gamma diversity : a measure of the overall diversity within a large region.
The values of biological diversity
- Human society depend on biological diversity for almost all the food supply, half of its medicines, much of its clothing and in some region virtually all of its fuel and building material and as well as, of course, an important part of its mental and spiritual welfare.
- Ecological services Biological diversity as a resource. The three main approaches used for determining the value of biological resources.
- Consumptive use value: The biological resources are consumed directly, without passing to the market. Assessing the value of nature’s products - such as fire wood, fodder, game meat, etc.
- Productive use value: The resource comes through market or trading. Assessing the value of products that are commercially harvested, such as timber, fish, game meat sold in a market, ivory, and medicinal plants.
- Non-consumptive use value: The resources meant for the future potential uses of biodiversity (tourism, scientific research) and ecological balance.
Benefits of
biodiversity
1. Economical
benefits –
- Food value – providing food to the human population on this earth for thousands of years. In the process of development of human civilization, man has unfolded many plant and animal life forms which are directly or indirectly helpful for him in solving his food problem. Due to the scientific advancement many new taxa have been discovered which are high yielding.
- Commercial value –timber which is a major component of material used for providing shelter to man. Natural fibres like cotton and silk are still used for clothing by human population.
- Medicinal value –Medicines, drugs and pharmaceuticals. Many plant genetic resources are used from derivation of basic drugs. These plant resources vary from actinomycetes and fungi to large trees. Traditional knowledge of indigenous people still keeps an edge over the scientific knowledge in this field. This benefit of biodiversity is still unexplored as the scientists could assess a small fraction of biodiversity for their potential for medicine and agriculture.
- Aesthetic value – Man has always been fascinated by the natural beauty and nature has inspired him resulting in development of his moral and ethical values. This intrinsic value of plants and animals are independent of their economic and commercial value. Wonderful plants and animals of this planet not only reflect their aesthetic value but they can make us think of the creator. This opens doors for spiritually which envisages to live in harmony with the nature.
2. Ecological
benefits/services (Indirect use value) – Biodiversity supplies the buffering
capacity and stability to life on the planet by maintaining the interactive dynamics
of the ecosystems of the world.
Causes of
biodiversity loss
The Millennium
Ecosystem Assessment identifies habitat change, climate change, invasive
species, over-exploitation and pollution as the primary drivers leading to loss
of biodiversity.
- Habitat change : Humans have had an effect on every habitat on Earth, particularly due to the conversion of land for agriculture. Cultivated systems (areas where at least 30% of the landscape is in croplands, shifting cultivation, confined livestock production, or freshwater aquaculture) now cover one quarter of Earth’s terrestrial surface. Habitat loss also occurs in coastal and marine systems, though these changes are less well documented. Trawling of the seabed, for instance, can significantly reduce the diversity of benthic habitats.
- Climate change : Observed recent changes in climate, especially warmer regional temperatures, have already had significant impacts on biodiversity and ecosystems, including causing changes in species distributions, population sizes, the timing of reproduction or migration events, and an increase in the frequency of pest and disease outbreaks. By the end of the twenty-first century, climate change and its impacts are likely to be the dominant direct driver of biodiversity loss and changes in ecosystem services globally.
- Invasive Species : The spread of invasive alien species has increased because of increased trade and travel. While increasingly there are measures to control some of the pathways of invasive species, for example, through quarantine measures and new rules on the disposal of ballast water in shipping, several pathways are not adequately regulated, particularly with regard to introductions into freshwater systems.
- Over-exploitation : For marine systems, the dominant direct driver of change globally has been over fishing. Demand for fish as food for people and as feed for aquaculture production is increasing, resulting in increased risk of major, long-lasting collapses of regional marine fisheries. 50% of the world’s commercial marine fisheries are fully exploited whilst 25% are being over exploited. For example, the Atlantic cod stocks off the east coast of Newfoundland collapsed in 1992, forcing the closure of the fishery, the depleted stocks may not recover even if harvesting is significantly reduced or eliminated.
- Pollution (especially nutrient loading) : Since 1950, human mediated increases in nitrogen, phosphorus, sulphur, and other nutrients (nutrient loading) has emerged as one of the most important drivers of ecosystem change in terrestrial, freshwater, and coastal ecosystems, and this driver is projected to increase substantially in the future. For example, humans now produce more biologically available nitrogen than is produced by all natural pathways combined. Aerial deposition of reactive nitrogen into natural terrestrial ecosystems, especially temperate grasslands, shrub-lands, and forests, leads directly to lower plant diversity; excessive levels of reactive nitrogen in water bodies, including rivers and other wetlands, frequently leads to algal blooms and eutrophication in inland waters and coastal areas. Similar problems have resulted from phosphorus, the use of which has tripled between 1960 and 1990. Nutrient loading will become an increasingly severe problem, particularly in developing countries and particularly in East and South Asia.
The World
Conservation Union (IUCN) (formerly known as International Union for the Conservation of
Nature and Natural Resources, IUCN) has recognized eight Red List categories
according to the conservation status of species. These categories are defined
below :
The IUCN Threat
Categories
- Extinct : A taxon is extinct when there is no reasonable doubt that the last individual has died. Extinct in the wild A taxon is extinct in the wild when exhaustive surveys in known and/or expected habitats have failed to record an individual.
- Critically endangered : A taxon is critically endangered when it is facing high risk of extinction in the wild in immediate future.
- Endangered : A taxon is endangered when it is not critically endangered but is facing a very high risk of extinction in the wild in near future.
- Vulnerable : A taxon is vulnerable when it is not critically endangered or endangered but is facing high risk of extinction in the wild in the medium term future.
- Lower risk : A taxon is lower risk when it has been evaluated and does not satisfy the criteria for critically endangered, endangered or vulnerable.
- Data deficient : A taxon is data deficient when there is inadequate information to make any direct or indirect assessment of its risk of extinction.
- Not evaluated : A taxon is not evaluated when it has not yet been assessed against the above criteria.
Examples of species which are categorised by Red list by IUCN (The International Union for conservation of Nature)
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| Chinese Pangulin : Critically Endangered Species |
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| Scimitar Oryx : Extinct Species |
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| Gaur (Indian Bias) : Vulnerable Species |
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| Great Indian Bustard : Endangered Species |
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| Primates : Least Concerned Species |
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| Nilgiri Tahr : Endangered Species |
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| Few Species categorised as Not Threatened |
Status of threatened species
The IUCN Red List
is an authentic source of information for this purpose. The 2000 Red List is
the latest available. It uses a set of criteria, relevant to all species and
all regions of the world, to evaluate the extinction risk of species. The 2000
Red List contains assessment of more than 18,000 species; 11,000 of which are
threatened (5,485 animals and 5611 plants). Out of these, 1,939 are listed as
critically endangered (925 animals, and 1,014 plants).According to the Red
List, in India, 44 plant species are critically endangered.,113 endangered and
87 vulnerable. Amongst animals, 18 are critically endangered, 54 endangered and
143 Vulnerable. A few examples of these plant and animals are given below :
Examples of
threatened species in India
- Critically endangered : Plant Species - Berberis nilghiriensis, Animal Species - Sus salvanius, (Pigmy hog)
- Endangered Plant : Species - Bentinckta nicobarica, Animal Species - Allurus fulgens , (Red Panda)
- Vulnerable : Plant Species - Cupressus cashmeriana, Animal Species - Antilope cervicapra, (Black buck)
Biodiversity Conservation
Why Should We
Conserve Biodiversity?
There are many
reasons, some obvious and others not so obvious, but all equally important.
They can be grouped into three categories: narrowly utilitarian, broadly
utilitarian, and ethical. The narrowly utilitarian arguments for conserving
biodiversity are obvious; humans derive countless direct economic benefits from
nature-food (cereals, pulses, fruits), firewood, fibre, construction material, industrial
products (tannins, lubricants, dyes, resins, perfumes) and products of
medicinal importance. More than 25 per cent of the drugs currently sold in the
market worldwide are derived from plants and 25,000 species of plants
contribute to the traditional medicines used by native peoples around the
world. Nobody knows how many more medicinally useful plants there are in
tropical rain forests waiting to be explored. With increasing resources put
into ‘bioprospecting’ (exploring molecular, genetic and species-level diversity
for products of economic importance), nations endowed with rich biodiversity
can expect to reap enormous benefits. The broadly utilitarian argument says
that biodiversity plays a major role in many ecosystem services that nature
provides. The fast-dwindling Amazon forest is estimated to produce, through
photosynthesis, 20 per cent of the total oxygen in the earth’s atmosphere. Can
we put an economic value on this service by nature? You can get some idea by
finding out how much your neighborhood hospital spends on a cylinder of oxygen.
Pollination (without which plants cannot give us fruits or seeds) is another
service, ecosystems provide through pollinators layer – bees, bumblebees, birds
and bats. What will be the costs of accomplishing pollination without help from
natural pollinators? There are other intangible benefits – that we derive from
nature–the aesthetic pleasures of walking through thick woods, watching spring
flowers in full bloom or waking up to a bulbul’s song in the morning. Can we
put a price tag on such things? The ethical argument for conserving
biodiversity relates to what we owe to millions of plant, animal and microbe
species with whom we share this planet. Philosophically or spiritually, we need
to realise that every species has an intrinsic value, even if it may not be of
current or any economic value to us. We have a moral duty to care for their
well-being and pass on our biological legacy in good order to future
generations. How do we conserve Biodiversity? When we conserve
and protect the whole ecosystem, its biodiversity at all levels is protected -
we save the entire forest to save the tiger. This approach is called in situ
(on site) conservation. However, when there are situations where an animal or
plant is endangered or threatened and needs urgent measures to save it from
extinction, ex situ (off site) conservation is the desirable approach.
In situ conservation – Faced with the conflict between development and conservation, many nations find it unrealistic and economically not feasible to conserve all their biological wealth. Invariably, the number of species waiting to be saved from extinction far exceeds the conservation resources available. On a global basis, this problem has been addressed by eminent conservationists. They identified for maximum protection certain ‘biodiversity hotspots’ regions with very high levels of species richness and high degree of endemism (that is, species confined to that region and not found anywhere else). Initially 25 biodiversity hotspots were identified but subsequently nine more have been added to the list, bringing the total number of biodiversity hotspots in the world to 34. These hotspots are also regions of accelerated habitat loss. Three of these hotspots – Western Ghats and Sri Lanka, Indo-Burma and Himalaya – cover our country’s exceptionally high biodiversity regions.
Although all the
biodiversity hotspots put together cover less than 2 percent of the earth’s
land area, the number of species they collectively harbour is extremely high
and strict protection of these hotspots could reduce the ongoing mass
extinctions by almost 30 per cent. In India, ecologically unique and
biodiversity-rich regions are legally protected as biosphere reserves, national
parks and sanctuaries. India now has 14 biosphere reserves, 90 national parks
and 448 wildlife sanctuaries. India has also a history of religious and
cultural traditions that emphasised protection of nature. In many cultures,
tracts of forest were set aside, and all the trees and wildlife within were
venerated and given total protection. Such sacred groves are found in Khasi and
Jaintia Hills in Meghalaya, Aravalli Hills of Rajasthan, Western Ghat regions
of Karnataka and Maharashtra and the Sarguja, Chanda and Bastar areas of Madhya
Pradesh. In Meghalaya, the sacred groves are the last refuges for a large
number of rare and threatened plants.
Ex situ Conservation – In this approach, threatened animals and plants are taken out from their natural habitat and placed in special setting where they can be protected and given special care. Zoological parks, botanical gardens and wildlife safari parks serve this purpose. There are many animals that have become extinct in the wild but continue to be maintained in zoological parks. In recent years ex situ conservation has advanced beyond keeping threatened species in enclosures. Now gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques, eggs can be fertilised in vitro, and plants can be propagated using tissue culture methods. Seeds of different genetic strains of commercially important plants can be kept for long periods in seed banks. Biodiversity knows no political boundaries and its conservation is therefore a collective responsibility of all nations. The historic Convention on Biological Diversity (‘The Earth Summit’) held in Rio de Janeiro in 1992, called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilisation of its benefits. In a follow-up, the World Summit on Sustainable Development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010, a significant reduction in the current rate of biodiversity loss at global, regional and local levels.
Multilateral
Environment Agreement
In response to the
current rate of biodiversity loss, and on the grounds that biodiversity is a
common concern for humankind, the Convention on Biological Diversity (CBD)was
opened for signature in 1992. As of June 2013 it has been ratified by 193
parties (governments). The CBD provides a global legal framework for action on
biodiversity and is considered a key instrument for sustainable development.
Its three main goals are:
- The conservation of biological diversity;
- The sustainable use of the components of biological diversity;
- The fair and equitable sharing of the benefits arising from the use of genetic resources.
The CBD’s governing
body is the Conference of the Parties (COP). It holds periodic meetings to review
progress on the Convention targets, and advance its implementation. To support
implementation of the CBD, the United Nations General Assembly declared
2011-2020 the United Nations Decade on Biodiversity and adopted the Strategic
Plan for Biodiversity 2011-2020. The Strategy is a ten-year framework for
action adopted by signatory countries in 2010 in Nagoya, Japan. It builds on
the vision that “by 2050, biodiversity is valued, conserved, restored and
wisely used, maintaining ecosystem services, sustaining a healthy planet and
delivering benefits essential for all people”. The Strategy calls for all
countries and stakeholders to effectively implement the three objectives of the
CBD by establishing national and regional targets, feeding into the five strategic
goals and 20 global targets (collectively known as the Aichi Biodiversity
Targets) outlined by the Strategy. The primary framework for action set forth
by the CBD is the ecosystem approach, an integrated strategy for the management
of biodiversity resources.
Biodiversity is
also at the centre of a number of other Conventions e.g. the Convention on
Migratory Species (CMS), the International Treaty on Plant Genetic Resources
for Food and Agriculture (Plant Treaty), The Convention on International Trade in
Endangered Species of Wild Fauna and Flora (CITES). It is also the subject of a
number of associated Protocols such as the Specially Protected Areas Protocol
and the Cartagena Protocol. A new platform, the Intergovernmental
Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), was
established by the international community in 2012 and is open to all United
Nations member countries. It is an independent intergovernmental body committed
to providing scientifically-sound assessments on the state of the planet’s
biodiversity in order to support informed decision-making on biodiversity and
ecosystem services conservation and use around the world.
Measuring and
monitoring biodiversity
Over the last 30
years, many different definitions of biodiversity have been used. As early as
1992, the year the Convention on Biological Diversity was opened for signature
at the Rio Earth Summit, it was noted that the definitions of biodiversity are ‘‘as
diverse as the biological resource’’. While the CBD definition is commonly
accepted, the variety of definitions of biodiversity is particularly relevant
when it comes to the scientific measurement of biodiversity. For the purposes
of detailed analysis, and the creation of indicators to measure or monitor trends,
exactly how biodiversity is defined will influence what is measured.
Biodiversity indicators aim at using quantitative data to measure aspects of
biodiversity, ecosystem condition, services, and drivers of change. This advances
understanding of how biodiversity is changing over time and space, why it is
changing, and what the consequences of the changes are for ecosystems, their
services, and human well-being. The huge variety of elements included in the
definition of biodiversity results in a varied set of methodologies to measure
the natural environment. There is no unified metric for quantitative
measurement. The variety of metrics employed include : species richness (number
of species); population number (number of genetically distinct populations of a
particular species defined by analysis of a specific element of its genetic
makeup) ; genetic diversity (The variation in the amount of genetic information
within and among individuals of a population, a species, an assemblage, or a
community ; species evenness (measurement of how evenly individuals are
distributed among species) ; and phenotypic (organism characteristics)
variance, (the measurement of the different between the phenotypes within a
sample).
Biodiversity measurement
and policy
The detail of how
to measure biodiversity is an area of discussion particularly relevant at the
science/policy interface. The CBD-mandated Biodiversity Indicators Partnership
(BIP) promotes the development of indicators in support of the CBD and related
Conventions, national and regional governments and a range of other sectors.
Indicators initiated under the partnership are linked to the goals of the
Strategic Plan for Biodiversity 2011-2020 and include habitat extent, protected
areas and species extinction.
Recent Transition in Biodiversity Conservation
Recent Transition in Biodiversity Conservation





































