Biosphere
• Food, from crops and domestic animals,
providing human metabolic requirements.
• Food, for all forms of life which live as interdependent
species in a community and
form food chains in nature on which man is
dependent.
• Energy needs: Biomass fuel wood collected
from forests and plantations, along with
other forms of organic matter, used as a
source of energy.
• Timber and other construction materials.
This is the relatively thin layer on the earth in
which life can exist. Within it the air, water, rocks
and soil and the living creatures, form structural
and functional ecological units, which together
can be considered as one giant global living system,
that of our Earth itself. Within this framework,
those characterised by broadly similar
geography and climate, as well as communities
of plant and animal life can be divided for convenience
into different biogeographical realms.
These occur on different continents. Within
these, smaller biogeographical units can be identified
on the basis of structural differences and
functional aspects into distinctive recognizable
ecosystems, which give a distinctive character
to a landscape or waterscape. Their easily visible
and identifiable characteristics can be described
at different scales such as those of a
country, a state, a district or even an individual
valley, hill range, river or lake.
The simplest of these ecosystems to understand
is a pond. It can be used as a model to understand
the nature of any other ecosystem and to
appreciate the changes over time that are seen
in any ecosystem. The structural features of a
pond include its size, depth and the quality of
its water. The periphery, the shallow part and
the deep part of the pond, each provide specific
conditions for different plant and animal
communities. Functionally, a variety of cycles
such as the amount of water within the pond at
different times of the year, the quantity of nutrients
flowing into the pond from the surrounding
terrestrial ecosystem, all affect the ‘nature’
of the pond.
Natural cycles between the spheres: All four
spheres are closely inter-linked systems and are
dependent on the integrity of each other. Disturbing
one of these spheres in our environment
affects all the others.
The linkages between them are mainly in the
form of cycles. For instance, the atmosphere,
hydrosphere and lithosphere are all connected
through the hydrological cycle. Water evaporated
from the hydrosphere (the seas and freshwater
ecosystems), forms clouds in the atmosphere.
This becomes rain, which provides moisture
for the lithosphere, on which life depends.
The rain also acts on rocks as an agent of erosion
and over millions of years has created soil,
on which plant life grows. Atmospheric movements
in the form of wind, break down rocks
into soil. The most sensitive and complex linkages
are those between the atmosphere, the
hydrosphere and the lithosphere on the one
hand, with the millions of living organisms in
the biosphere on the other. All living organisms
which exist on earth live only in the relatively
thin layer of the lithosphere and hydrosphere
that is present on the surface of land and in the
water. The biosphere which they form has
countless associations with different parts of the
three other ‘spheres’.
It is therefore essential to understand the interrelationships
of the separate entities soil, water,
air and living organisms, and to appreciate
the value of preserving intact ecosystems as a
whole
RENEWABLE AND NON-RENEWABLE RESOURCES
Ecosystems act as resource producers and processors.
Solar energy is the main driving force
of ecological systems, providing energy for the
growth of plants in forests, grasslands and
aquatic ecosystems. A forest recycles its plant
material slowly by continuously returning its
dead material, leaves, branches, etc. to the soil.
Grasslands recycle material much faster than
forests as the grass dries up after the rains are
over every year. All the aquatic ecosystems are
also solar energy dependent and have cycles of
growth when plant life spreads and aquatic
animals breed. The sun also drives the water
cycle.
Our food comes from both natural and agricultural
ecosystems. Traditional agricultural ecosystems
that depended on rainfall have been modified
in recent times to produce more and more
food by the addition of extra chemicals and
water from irrigation systems but are still dependent
on solar energy for the growth of crops.
Moreover modern agriculture creates a variety
of environmental problems, which ultimately
lead to the formation of unproductive land.
These include irrigation, which leads to the
development of saline soil, and the use of artificial
fertilizers eventually ruin soil quality, and
pesticides, which are a health hazard for
humans as well as destroying components vital
to the long-term health of agricultural ecosystems.
To manufacture consumer products, industry
requires raw materials from nature, including
water, minerals and power. During the manufacturing
process, the gases, chemicals and
waste products pollute our environment, unless
the industry is carefully managed to clean up
this mess.
Natural resources and associated problems:
The unequal consumption of natural resources:
A major part of natural resources are
today consumed in the technologically advanced
or ‘developed’ world, usually termed ‘the North’.
The ‘developing nations’ of ‘the South’, including
India and China, also over use many resources
because of their greater human population.
However, the consumption of resources
per capita (per individual) of the developed countries
is up to 50 times greater than in most developing
countries. Advanced countries produce
over 75% of global industrial waste and greenhouse
gases.
Energy from fossil fuels is consumed in relatively
much greater quantities in developed countries.
Their per capita consumption of food too is
much greater as well as their waste of enormous
quantities of food and other products,
such as packaging material, used in the food
industry. The USA for example with just 4% ofthe world’s population consumes about 25%
of the world’s resources.
Producing animal food for human consumption
requires more land than growing crops. Thus
countries that are highly dependent on non-vegetarian
diets need much larger areas for
pastureland than those where the people are
mainly vegetarian.
Planning Landuse: Land itself is a major resource,
needed for food production, animal
husbandry, industry, and for our growing human
settlements. These forms of intensive landuse
are frequently extended at the cost of ‘wild
lands’, our remaining forests, grasslands, wetlands
and deserts. Thus it is essential to evolve a
rational land-use policy that examines how much
land must be made available for different purposes
and where it must be situated. For instance,
there are usually alternate sites at which
industrial complexes or dams can be built, but a
natural wilderness cannot be recreated artificially.
Scientists today believe that at least 10
percent of land and water bodies of each ecosystem
must be kept as wilderness for the longterm
needs of protecting nature and natural
resources.
Land as a resource is now under serious pressure
due to an increasing ‘land hunger’ - to produce
sufficient quantities of food for an exploding
human population. It is also affected by degradation
due to misuse. Land and water resources
are polluted by industrial waste and rural
and urban sewage. They are increasingly
being diverted for short-term economic gains
to agriculture and industry. Natural wetlands of
great value are being drained for agriculture and
other purposes. Semi-arid land is being irrigated
and overused.
The most damaging change in landuse is demonstrated
by the rapidity with which forests have
vanished during recent times, both in India and
in the rest of the world. Forests provide us with
a variety of services. These include processes
such as maintaining oxygen levels in the atmosphere,
removal of carbon dioxide, control over
water regimes, and slowing down erosion and
also produce products such as food, fuel, timber,
fodder, medicinal plants, etc. In the long
term, the loss of these is far greater than the
short-term gains produced by converting forested
lands to other uses.
The need for sustainable lifestyles: The quality
of human life and the quality of ecosystems
on earth are indicators of the sustainable use of
resources. There are clear indicators of sustainable
lifestyles in human life.
• Increased longevity
• An increase in knowledge
• An enhancement of income.
These three together are known as the ‘Human
development index’.
The quality of the ecosystems have indicators
that are more difficult to assess.
• A stabilized population.
• The long term conservation of biodiversity.
• The careful long-term use of natural resources.
• The prevention of degradation and pollution
of the environment.
Non-renewable resources :
These are minerals that have been formed in the lithosphere over millions of years and constitute a closed system. These non-renewable resources, once used, remain on earth in a different form and, unless recycled, become waste material. Non-renewable resources include fossil fuels such as oil and coal, which if extracted at the present rate, will soon be totally used up. The end products of fossil fuels are in the form of heat and mechanical energy and chemical compounds, which cannot be reconstituted as a resource. 2.2.3 Renewable resources Though water and biological living resources are considered renewable. They are in fact renewable only within certain limits. They are linked to natural cycles such as the water cycle. • Fresh water (even after being used) is evaporated by the sun’s energy, forms water vapour and is reformed in clouds and falls to earth as rain. However, water sources can be overused or wasted to such an extent that they locally run dry. Water sources can be so heavily polluted by sewage and toxic substances that it becomes impossible to use the water. • Forests, once destroyed take thousands of years to regrow into fully developed natural ecosystems with their full complement of species. Forests thus can be said to behave like non-renewable resources if overused. • Fish are today being over-harvested until the catch has become a fraction of the original resource and the fish are incapable of breeding successfully to replenish the population. • The output of agricultural land if mismanaged drops drastically. • When the population of a species of plant or animal is reduced by human activities, until it cannot reproduce fast enough to maintain a viable number, the species becomes extinct. • Many species are probably becoming extinct without us even knowing, and other linked species are affected by their loss.
Non-renewable resources :
These are minerals that have been formed in the lithosphere over millions of years and constitute a closed system. These non-renewable resources, once used, remain on earth in a different form and, unless recycled, become waste material. Non-renewable resources include fossil fuels such as oil and coal, which if extracted at the present rate, will soon be totally used up. The end products of fossil fuels are in the form of heat and mechanical energy and chemical compounds, which cannot be reconstituted as a resource. 2.2.3 Renewable resources Though water and biological living resources are considered renewable. They are in fact renewable only within certain limits. They are linked to natural cycles such as the water cycle. • Fresh water (even after being used) is evaporated by the sun’s energy, forms water vapour and is reformed in clouds and falls to earth as rain. However, water sources can be overused or wasted to such an extent that they locally run dry. Water sources can be so heavily polluted by sewage and toxic substances that it becomes impossible to use the water. • Forests, once destroyed take thousands of years to regrow into fully developed natural ecosystems with their full complement of species. Forests thus can be said to behave like non-renewable resources if overused. • Fish are today being over-harvested until the catch has become a fraction of the original resource and the fish are incapable of breeding successfully to replenish the population. • The output of agricultural land if mismanaged drops drastically. • When the population of a species of plant or animal is reduced by human activities, until it cannot reproduce fast enough to maintain a viable number, the species becomes extinct. • Many species are probably becoming extinct without us even knowing, and other linked species are affected by their loss.
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