Kegy 214
Kegy 214
Kegy 214
UNIT
VI
Rationalised-2023-24
CHAPTER
Y
ou have already learnt about the the earth are today extinct. Biodiversity is not
geomorphic processes particularly found evenly on the earth. It is consistently
weathering and depth of weathering richer in the tropics. As one approaches the
mantle in different climatic zones. See the polar regions, one finds larger and larger
Figure 5.2 in Chapter 5 in order to recapitulate. populations of fewer and fewer species.
You should know that this weathering mantle Biodiversity itself is a combination of two
is the basis for the diversity of vegetation and words, Bio (life) and diversity (variety). In
hence, the biodiversity. The basic cause for simple terms, biodiversity is the number and
such weathering variations and resultant variety of organisms found within a specified
biodiversity is the input of solar energy and geographic region. It refers to the varieties of
water. No wonder that the areas that are rich plants, animals and micro-organisms, the
in these inputs are the areas of wide spectrum genes they contain and the ecosystems they
of biodiversity. form. It relates to the variability among living
organisms on the earth, including the
Biodiversity as we have today is the result variability within and between the species and
of 2.5-3.5 billion years of evolution. Before that within and between the ecosystems.
the advent of humans, our earth Biodiversity is our living wealth. It is a result
supported more biodiversity than in any
of hundreds of millions of years of evolutionary
other period. Since, the emergence of
history.
humans, however, biodiversity has begun
a rapid decline, with one species after Biodiversity can be discussed at three
another bearing the brunt of extinction levels : (i) Genetic diversity; (ii) Species diversity;
due to overuse. The number of species (iii) Ecosystem diversity.
globally vary from 2 million to 100 million,
with 10 million being the best estimate. Genetic Diversity
New species are regularly discovered
most of which are yet to be classified (an Genes are the basic building blocks of various
estimate states that about 40 per cent of life forms. Genetic biodiversity refers to the
fresh water fishes from South America variation of genes within species. Groups of
are not classified yet). Tropical forests are individual organisms having certain
very rich in bio-diversity. similarities in their physical characteristics are
called species. Human beings genetically
Biodiversity is a system in constant belong to the homo sapiens group and also
evolution, from a view point of species, as well differ in their characteristics such as height,
as from view point of an individual organism. colour, physical appearance, etc., considerably.
The average half-life of a species is estimated This is due to genetic diversity. This genetic
at between one and four million years, and 99 diversity is essential for a healthy breeding of
per cent of the species that have ever lived on population of species.
Rationalised-2023-24
116 FUNDAMENTALS OF PHYSICAL GEOGRAPHY
Rationalised-2023-24
BIODIVERSITY AND CONSERVATION 117
ecosystems of which we are also a species. This The International Union of Conservation of
fact must be drawn upon every one of us so Nature and Natural Resources (IUCN) has
that we live and let other species also live their classified the threatened species of plants and
lives. animals into three categories for the purpose
It is our ethical responsibility to consider of their conservation.
that each and every species along with us have
an intrinsic right to exist. Hence, it is morally Endangered Species
wrong to voluntarily cause the extinction of any
It includes those species which are in danger
species. The level of biodiversity is a good
of extinction. The IUCN publishes information
indicator of the state of our relationships with
about endangered species world-wide as the
other living species. In fact, the concept of
Red List of threatened species.
biodiversity is an integral part of many human
cultures.
LOSS OF BIODIVERSITY
Since the last few decades, growth in human
population has increased the rate of
consumption of natural resources. It has
accelerated the loss of species and habitation
in different parts of the world. Tropical regions
which occupy only about one-fourth of the
total area of the world, contain about three-
fourth of the world human population. Over-
exploitation of resources and deforestation
have become rampant to fulfil the needs of large
population. As these tropical rain forests
contain 50 per cent of the species on the earth, Figure 14.2 : Red Panda — an endangered species
destruction of natural habitats have proved
Vulnerable Species
disastrous for the entire biosphere.
Natural calamities such as earthquakes, This includes the species which are likely to
floods, volcanic eruptions, forest fires, be in danger of extinction in near future if the
droughts, etc. cause damage to the flora and factors threatening to their extinction continue.
fauna of the earth, bringing change the Survival of these species is not assured as their
biodiversity of respective affected regions. population has reduced greatly.
Pesticides and other pollutants such as
hydrocarbons and toxic heavy metals destroy Rare Species
the weak and sensitive species. Species which Population of these species is very small in the
are not the natural inhabitants of the local world; they are confined to limited areas or
habitat but are introduced into the system, are
thinly scattered over a wider area.
called exotic species. There are many
examples when a natural biotic community of
CONSERVATION OF BIODIVERSITY
the ecosystem suffered extensive damage
because of the introduction of exotic species. Biodiversity is important for human existence.
During the last few decades, some animals like All forms of life are so closely interlinked that
tigers, elephants, rhinoceros, crocodiles, minks disturbance in one gives rise to imbalance in
and birds were hunted mercilessly by poachers the others. If species of plants and animals
for their horn, tusks, hides, etc. It has resulted become endangered, they cause degradation
in the rendering of certain types of organisms in the environment, which may threaten
as endangered category. human being’s own existence.
Rationalised-2023-24
118 FUNDAMENTALS OF PHYSICAL GEOGRAPHY
Rationalised-2023-24
BIODIVERSITY AND CONSERVATION 119
EXERCISES
Rationalised-2023-24
120 FUNDAMENTALS OF PHYSICAL GEOGRAPHY
Project Work
Collect the names of national parks, sanctuaries and biosphere reserves of the
state where your school is located and show their location on the map of India.
Rationalised-2023-24