Module 3 ENVIRONMENT AND ECOLOGY _VTU

ENERGY AND ENVIRONMENT
MODULE -3
ENVIRONMENT & ECOSYSTEM
Deviprasad N Mirashi
Assistant Professor
BIET, Davangere

 Environment.
Definition
• Environment is defined as the sum total of biotic and abiotic components that
surrounded by any organisms.
Biotic components
1. INTRODUCTION
Producers DecomposersConsumers

• Over the fast two centuries both human populations and economic wealth of world have grown
rapidly, these two factors which increases the resource consumption significantly.
Evident : Agriculture, Food production, Industrial development, Energy production and
Urbanization
 Stress on Earth by Human population
• In just few generations mankind started process of exhausting fossil fuels that were generated
over several hundred million years.
•The emission of from human activities that increased the global temperature for several degrees.
Carbon dioxide and other gases

• Chlorofluoro carbon and halons which releasing to the atmosphere it depleting the ozone that
faster than it formed. The ultraviolet rays which coming from the solar radiations that affects on
the human health may cause skin cancer and eye cataract problems.
• Almost half of the earths land surface utilized for human actions which makes significant
consequences on the biodiversity, nutrient cycle, soil structure and climate.
• Maximum fresh water reserves are used by man kind for direct and indirect utility, which
depleting the underground water rapidly in many areas.
•About quarter of recognized marine fisheries are over exploited and depleted are remaining
are there in limit of exploitation.
•Coastal and marine habitants are dramatically altered. 50% of the mangroves and wetland have
been destroyed.

• Most of the waste we dump into the air water and land eventually end up in the oceans. Oil
sticks. floating plastic debris, polluted estuaries, and beaches which adversely effects on the
aquatic living organisms. We are using worlds oceans as a largest trash dump.
• Extinction rates are increasing sharply in the marine and terrestrial ecosystem around the
world. Number of birds, animals, marine and fresh water creature have dropped by more
than quarter in since 1970.
•About 8.1 million kilometers of once productive land (crop land, forest and grass land) have
become desert in the 50 years. Each year, almost 61,000 square kilometer of new desert are
formed.
• Millions of hectares of grass land have been overgrazed, some especially in the Africa and
the middle east have been converted into desert.

• Almost half of the worlds original expanse of tropical forest has been cleared. Within the 30 to
50 years there may be little of these forests left. One third of the people cannot get enough fuel
wood to meet their basic needs and many are forced to meet their needs by cutting trees faster
than they are being replenished.
•An estimated 36,500 species of plants and animals become extinct each year mostly because
of human activities. If deforestation ( especially of tropical forest ), desertification, and
destruction of wet land and coral reefs if it continues in present rate 5,00,000 and perhaps 1
million species will extinct over next 20 years.
•Today more than 10 million people world wide have lost their home and land because of
environmental degradation. These people are now worlds single largest class of refugees.
•Top soil eroding faster than it forms on about 35% of the world crop lands.
• In developing countries 61% of people living in rural areas and 26 % of urban dwellers do
not have access to safe drinking water. Each year, 5 million die from preventable water born
dieses.

 Environmental Studies
Environmental studies deals with every issue that affects an organism. It is essentially a
multidisciplinary approach that brings about an positive reception of our natural world and
human impacts on its integrity. It is an applied science as its seeks practical answers to making
human civilization sustainable on the earth’s finite resources. Its components include biology,
geology, chemistry, physics, engineering, sociology, health, anthropology, economics, statistics,
computers and philosophy.

 Components of Environment and their interaction

Module 3 ENVIRONMENT AND ECOLOGY _VTU

 Scope
• As we look around at the area in which we live, we see that our surroundings were originally
a natural landscape such as a forest, a river, a mountain, a desert, or a combination of these
elements. Most of us live in landscapes that have been heavily modified by human beings, in
villages, towns or cities. But even those of us who live in cities get our food supply from
surrounding villages and these in turn are dependent on natural landscapes such as forests,
grasslands, rivers, seashores, for resources such as water for agriculture, fuel wood, fodder, and
fish. Thus our daily lives are linked with our surroundings and inevitably affects them. We use
water to drink and for other day-to-day activities. We breathe air, we use resources from which
food is made and we depend on the community of living plants and animals which form a web of
life, of which we are also a part. Everything around us forms our environment and our
livesdepend on keeping its vital systems as intact as possible.
Web of life

• Our dependence on nature is so great that we cannot continue to live without protecting the
earth’s environmental resources. Thus most traditions refer to our environment as ‘Mother
Nature’ and most traditional societies have learned that respecting nature is vital for their
livelihoods. This has led to many cultural practices that helped traditional societies protect and
preserve their natural resources. Respect for nature and all living creatures is not new to
India. All our traditions are based on these values. Emperor Ashoka’s edict proclaimed that all
forms of life are important for our well being in Fourth Century BC.
• Over the past 200 years however, modern societies began to believe that easy answers to the
question of producing more resources could be provided by means of technological innovations.
For example, though growing more food by using fertilizers and pesticides, developing better
strains of domestic animals and crops, irrigating farmland through mega dams and developing
industry, led to rapid economic growth, the ill effects of this type of development, led to
environmental degradation.
•The industrial development and intensive agriculture that provides the goods for our increasingly
consumer oriented society uses up large amounts of natural resources such as water, minerals,
petroleum products, wood, etc. Nonrenewable resources, such as minerals and oil are those
which will be exhausted in the future if we continue to extract these without a thought for
subsequent generations.

• Renewable resources, such as timber and water, are those which can be used but can be
regenerated by natural processes such as re growth or rainfall. But these too will be depleted if
we continue to use them faster than nature can replace them. For example, if the removal of
timber and firewood from a forest is faster than the re growth and regeneration of trees, it
cannot replenish the supply. And loss of forest cover not only depletes the forest of its resources,
such as timber and other non-wood products, but affect our water resources because an intact
natural forest acts like a sponge which holds water and releases it slowly. Deforestation leads to
floods in the monsoon and dry rivers once the rains are over.

 What is Sustainable utilization or development?
Interest
(Sustainable)
zero
(Unsustainable utilization)
Natural Resources = Money in Bank (Capital)
• Our natural resources can be compared with money in a bank. If we use it rapidly, the capital
will be reduced to zero. On the other hand, if we use only the interest, it can sustain us over
the longer term. This is called sustainable utilization or development

 Importance
• Environment is not a single subject. It is an integration of several subjects that
include both Science and Social Studies. To understand all the different aspects of
our environment we need to understand biology, chemistry, physics, geography,
resource management, economics and population issues. Thus the scope of
environmental studies is extremely wide and covers some aspects of nearly every
major discipline.
• Water, air, soil, minerals, oil, the products we get from forests, grasslands,
oceans and from agriculture and livestock, are all a part of our life support
systems. Without them, life itself would be impossible.

We waste or pollute large amounts of nature’s clean water; we create more and more
material like plastic that we discard after a single use; and we waste colossal amounts of
food, which is discarded as garbage. Manufacturing processes create solid waste
byproducts that are discarded, as well as chemicals that flow out as liquid waste and
pollute water, and gases that pollute the air. Increasing amounts of waste cannot be
managed by natural processes.
These accumulate in our environment, leading to a variety of diseases and other
adverse environmental impacts now seriously affecting all our lives. Air pollution
leads to respiratory diseases, water pollution to gastro-intestinal diseases, and
many pollutants are known to cause cancer.

 Need for public awareness
• As the earth’s natural resources are declining and our environment is being increasingly
degraded by human activities, it is evident that something needs to be done. We often feel that
managing all this is something that the Government should do. But if we go on endangering our
environment, there is no way in which the Government can perform all these clean-up functions.
It is the prevention of environment degradation in which we must all take part that must
become a part of all our lives. Just as for any disease, prevention is better than cure. To prevent
ill-effects on our environment by our actions, is economically more viable than cleaning up the
environment once it is damaged. Individually we can play a major role in environment
management. We can reduce wasting natural resources and we can act as watchdogs that inform
the Government about sources that lead to pollution and degradation of our environment.
• This can only be made possible through mass public awareness. Mass media such as
newspapers, radio, television, strongly influence public opinion. However, someone has to bring
this about. If each of us feels strongly about the environment, the press and media will add to our
efforts. Politicians in a democracy always respond positively to a strong publicly supported
movement. Thus if you join an NGO that supports conservation, politicians will make green
policies. We are living on spaceship earth with a limited supply of resources. Each of us is
responsible for spreading this message to as many people as possible.

 Suggested further activities for concerned students:
• Join local movements that support activities such as saving trees in your area, go on nature
treks, recycle waste, buy environmentally friendly products.
• Practice and promote good civic sense such as no spitting or tobacco chewing, no throwing
garbage on the road, no smoking in public places, no urinating or defecating in public places.
• Take part in events organized on World Environment Day, Wildlife Week, etc.
• Visit a National Park or Sanctuary, or spend time in whatever nature you have near your home.

 Institutions in Environment
• There are two type of institutions in environment, they are :
Government organization Non govt. organization
 Botanical Survey of India
(BSI)
 Zoological Survey of India
(ZSI)

BSI-Botanical Survey of India
• Established in 1890 at the Royal Botanic
Gardens, Calcutta.
• In 1952, plans were made to recognize the BSI
and formulate its objectives.
• The BSI currently has nine regional centers.

ZSI-Zoological Survey of India
• Established in 1916.
• It’s mandate was to do a symmetric survey of fauna in India.
• Its origins were collections based at the Indian Museum at
Calcutta, which was established in 1875.
• It has done an enormous amount of work on taxonomy and
ecology.
• It currently operates from 16 regional centers.

 BNHS-Bombay Natural History Society, Mumbai
• Begin as a small society of six members in 1883.
• Its influence is on wild life policy building, research,
popular publications.
• Publishes a popular magazine called Hornbill and also an
internationally well-known journal on Natural History.
• Helped the government to frame wild life related laws and
taken up battles such as ‘save the silent valley campaign’.
 Non government organizations :

 WWF-I World Wide Fund for Natural India, New Delhi
• Initiated in 1969 in Mumbai, after the head quarters is shifted to New
Delhi.
• Attention on wild life education and awareness.
• It runs several programs, including the Natural Clubs of India
program from school children.
 CSE-Center for Science and Environment, New Delhi
•The activities including organizing campaigns, holding workshops and conferences, and
producing environment related publications.
•Publication material is in the form of books, posters, video films and also conducts work shops
and seminars on bio-diversity related issues.

CPR-EEC CPR Environmental Education Center, Chennai
• Setup in 1988.
• Conducts a variety of programs to spread environmental awareness
and create an interest in conservation among the general public.
• To promote conservation of nature and natural resources.
• Its programs include components on wild life an biodiversity issues.
• Produces large number of publications.
 CEE-Center for Environmental Education, Ahemadabad
• Initiated in 1989.
• Wide range of programs on the environment and produces a variety of
educational material.
• CEE’s Training in Environment Education program has trained many
environmental educators.

 BVIEER-Bharati Vidyapeet Institute of Environmental
Education and Research, Pune
• Part of Bharati Vidyapeet deemed university.
• The institute has a PhD, master’s and Bachelor’s Program in
Environmental Sciences.
• It also offers an innovative diploma in Environment education
for in-service teachers.
• Biodiversity conservation is a major focus of its research
initiatives.

UKSN-Uttarkhand Seva Nidhi, Almora
• This organization is a Nodal agency that supports
NGOs in need of funds for their environment related
activities.
• Its main target is sustainable resource use at the
village level through training school children.
• Its environment education program covers about 500
schools

Kalpavriksh, Pune
• This NGO, initially Delhi based, is now working
from Pune.
• Works on a variety of fronts; education and
awareness; investigation and research; direct
action and lobbying; and litigation with regard
to environment and development issues.
• Responsible for developing India’s National
Biodiversity strategy and Action plan in 2003.

Salim Ali center for Ornithology and
Natural History (SACON), Coimbatore
• Intially conceived as being a wing of the BNHS,
it later evolved into an independent
organization based at Coimbatore in 1990.
• It has instituted a variety of field programs
that have added to the country’s information
on our threatened biodiversity.

WII- Wildlife Institute of India, Dehradun
• Established in 1982.
• This institute is established as a major training
for forest officials and for research in wild life
management.
• Its most significant publication has been
planning a Wild Life Protected Area Network
for India.

MCBT-Madras Crocodile Bank Trust,
Chennai
• The first Crocodile conservation breeding center in
Asia, was founded in 1976 to conserve Indian
Crocodiles an establish program for the conservation
an propagation of other species.
• MCBT has an ongoing Environmental Education
Program for the villages and schools that include
nature camps, training workshops for teachers.

People in Environment
• The following are the well-known names in the last
century include environmentalists, administrators,
legal experts, educationalists, and journalists.
– Indira Gandhi
– S.P.Gadgil
– M.S.Swaminathan
– Madhav Gadgil
– M.C.Mehta
– Anil Agarwal
– Medha Patkar
– Sunderlal Bahuguna

Indira Gandhi
• As PM played a very significant role in the
preservation of India’s Wild Life.
• During her period, the network and protected
areas grew from 65 to 98.
• Wild life protection act was formulated during
her period.

S.P.Godrej
• Was one of the India’s greatest supporter of
wild life conservation and nature awareness
programs.
• Between 1975 and 1999, received 10 awards
for his conservation activities, he was awarded
the Padmabhushan in 1999.

M S Swaminathan
• One of the India’s foremost agricultural
scientists.
• Founded the MS Swaminathan Research
Foundation in Chennai

Madhav Gadgil
• Well known ecologist in India.
• His interests range from broad ecological
issues such as developing community
Biodiversity registers studies on the behaviour
of mammals, birds, and insects.
• He was written several articles, published
papers in journals…

M.C.Mehta
• India’s most famous environmental lawyer.
• Since 1984, he has filed several public interest
litigations for supporting the cause of
environmental conservation.
• His most famous and long-drawn battles
supported by the supreme court include
protecting the Tajmahal, cleaning up the
Ganges river…..

Anil Agarwal
• Was a journalist who wrote the first report on
the state of India’s Environment in 1982.
• He founded the CES, an active NGO that
supports various environmental issues.

Medha Patkar
• Known as one of rural India’s Champions, has
supported the cause of the downtrodden
tribal people whose environment is being
affected by the dams on the Narmada River.

Sunderlal Bahuguna
• His chipko movement has become an
internationally well-known example of a
highly successfully conservation action
program through the efforts of local people
for guarding their forest resources.
• His fight to prevent the construction of Tehri
dam in a fragile earthquake-prone setting is a
battle that continues to wage

Activity 1:
 Take any article that you use in daily life – a bucket full of water, or an item of food, a table,
or a book. Trace its components journey backwards from your home to their origins as natural
resources in our environment. How many of these components are renewable resources and
how many non-renewable?
 Try to answer the questions above for one of the components in the article you chose in
Activity 1. Then answer the following questions:
Are you using that resource
unsustainably?
• In what ways could you reduce, reuse and recycle that resource?
• Is there an unequal distribution of this resource so that you are more fortunate than many
others who have less access to it?
Activity 2:
Activity 3:
• Think of all the things that you do in a day. List these activities and identify the main
resources used during these activities. What can you do to prevent waste, reuse articles that
you normally throw away, what recycled materials can you use?
• Think of the various energy sources you use everyday. How could you reduce their use?

Activity 4:
Exercises in self learning about the environment Attempt to assess the level of damage to the
environment due to your actions that have occurred during your last working day, the last
week, the last year. Then estimate the damage you are likely to do in your lifetime if you
continue in your present ways
Use the following examples for the above exercise: Example – Plastic: Plastic bags, plastic ball
pens Think about all the articles you use daily that are made from plastic. Plastic plays an
important part in our modern lives. Make a list of the plastic articles you usually use. How can
you reduce the amount of plastic you use?
 What effects does plastic have on our environment?
 Where did the plastic come from/ how is it made?
What happens to it when you throw it away/ where does it go?
Example – Fossil fuels:
How much do you use? Can you reduce your consumption?
What effect does it have on the air we breathe?
When we leave a motorbike or car running during a traffic stop, we do not usually remember
that the fuel we are wasting is a part of a nonrenewable resource that the earth cannot reform.
Once all the fossil fuels are burnt off, it will mean the end of oil as a source of energy. Only if
each of us contributes our part in conserving fossil based energy can we make it last longer on
earth.

Example – Water:
How much do you really need to use, as against how much you waste when you:
(a) Brush your teeth?
(b) Have a bath?
(c) Wash clothes?
(d) Wash the scooter or car?
• Where did the water come from?
• What is its actual source?
• How has it reached you?
• Where will the waste water go?
• Do you feel you should change the way you use water?
• How can you change this so that it is more sustainable?
Example – Food:
•Where has it come from?
•How is it grown?
•What chemicals are used in its production?
• How does it reach you? How is it cooked?
• How much is wasted? How is the waste disposed off?

Example – Paper:
•What is it made from?
•Where does it come from and what happens during manufacture?
•How much do you use and how much do you waste?
• How can you prevent it from being wasted?
Example – Electrical Energy:
How much do you use everyday? Where does it come from?
How do you waste it? How can you conserve energy?

ECOSYSTEM
• An ‘Ecosystem’ is a region with a specific and recognizable landscape form such as forest,
grassland, desert, wetland or coastal area. The nature of the ecosystem is based on its
geographical features such as hills, mountains, plains, rivers, lakes, coastal areas or islands. It is
also controlled by climatic conditions such as the amount of sunlight, the temperature and the
rainfall in the region. The geographical, climatic and soil characteristics form its non-living
(abiotic) component. These features create conditions that support a community of plants and
animals that evolution has produced to live in these specific conditions. The living part of the
ecosystem is referred to as its biotic component.
• Ecosystems have been formed on land and in the sea by evolution that has created species to
live together in a specific region. Thus ecosystems have both non-living (abiotic) and living
(biotic) components hat are typical to an area giving it its own special characteristics that are
easily observed.
•Ecosystems are divided into terrestrial or land based ecosystems, and aquatic ecosystems in
water. These form the two major habitat conditions for the Earth’s living organisms.
Definition: The living community of plants and animals in any area together with the non-living
components of the environment such as soil, air and water, constitute the ecosystem.

• Some ecosystems are fairly robust and are less affected by a certain level of human disturbance.
Others are highly fragile and are quickly destroyed by human activities. Mountain ecosystems are
extremely fragile as degradation of forest cover leads to severe erosion of soil and changes in
river courses. Island ecosystems are easily affected by any form of human activity which can lead
to the rapid extinction of several of their unique species of plants and animals. Evergreen forests
and coral reefs are also examples of species rich fragile ecosystems which must be protected
against a variety of human activities that lead to their degradation. River and wetland ecosystems
can be seriously affected by pollution and changes in surrounding land use.
 Understanding ecosystems
1. ‘What does the ecosystem look like?’
•One should be able to describe specific features of the different ecosystems in ones own
surroundings. Field observations must be made in both urban and natural surroundings.
2. What is its structure?
•Is it a forest, a grassland, a water body, an agricultural area, a grazing area, an urban area, an
industrial area, etc.?
•What you should see are its different characteristics. A forest has layers from the ground to the
canopy. A pond has different types of vegetation from the periphery to its center. The vegetation
on a mountain changes from its base to its summit.

3. What is the composition of its plant and animal species?
• List the well-known plants and animals you can see. Document their abundance and numbers
in nature: very common, common, uncommon, rare. Wild mammals will not be seen in large
numbers, cattle would be common. Some birds are common – which are the most common
species? Insect species are very common and most abundant. In fact there are so many that they
cannot be easily counted.
4.‘ How does the ecosystem work’?
The ecosystem functions through several biogeochemical cycles and energy transfer
mechanisms. Observe and document the components of the ecosystem which consists of its
non-living or abiotic features such as air, water, climate and soil. Its biotic components, the
various plants and animals. Both these aspects of the ecosystem interact with each other
through several functional aspects to form Nature’s ecosystems. Plants, herbivores and
carnivores can be seen to form food chains. All these chains are joined together to form a ‘web
of life’ on which man depends. Each of these use energy that comes from the sun and powers
the ecosystem.

 Ecosystem degradation
• Ecosystems are however frequently disrupted by human actions which lead to the extinction of
species of plants and animals that can live only in the different natural ecosystems. Some species
if eliminated seriously affect the ecosystem. These are called ‘keystone’ species. Extinction
occurs due to changes in land use. Forests are deforested for timber, wetlands are drained to
create more agricultural land and semi arid grasslands that are used as pastures are changed into
irrigated fields. Pollution from industry and waste from urban settings can also lead to extinction
of several species.
• The reason for the depletion of natural resources is two fold – our rapidly exploding population
that needs to sustain itself on resources, and the growth of affluent societies, which consume
and waste a very large proportion of resources and energy. Increasing extraction of resources
is at the cost of natural ecosystems, leading to a derangement of their important functions.
•Each of us in our daily lives use a variety of resources. If tracked back to their source, one finds
that the resources were originally obtained from nature and natural ecosystems. Our insensitivity
to using resources carefully has produced societies that nature can no longer sustain. If one
thinks before wasting resources such as water, reusing and recycling paper, using less
plastics that are non-degradable, definitely this can have positive implications on the
integrity of our natural resource base and conserve the resources that nature provides.

Resource utilization
• Though inequality in resource utilization has existed in every society, the number of individuals
that used a large proportion of resources was extremely limited. In recent times the proportion of
‘rich’ people in comfortable societies, grew rapidly.
•Inequality thus became a serious problem. Whereas in the past many resources such as timber
and fuel wood from the forest were extracted sustainably, this pattern has drastically changed
during the last century.
•The economically better off sections began to use greater amounts of forest products, while
those people who lived in the forest became increasingly poor. Similarly the building of large
irrigation projects led to wealth in those areas that had canals, while those who hand to remain
dependent on a constant supply of water from the river itself, found it difficult to survive.
•The key to this issue is the need for an ‘equitable’ distribution of all types of natural resources. A
more even sharing of resources within the community can reduce these pressures on the natural
ecosystems.

 Structure and functions of an Ecosystem
Components that make up the structural aspects of an ecosystem include:
1) Inorganic aspects – C, N, CO2, H2O.
2) Organic compounds – Protein, Carbohydrates, Lipids – link abiotic to bioticaspects.
3) Climatic regimes – Temperature, Moisture, Light & Topography.
4) Producers – Plants.
5) Macro consumers – Phagotrophs – Large animals.
6) Micro consumers – Saprotrophs, absorbers – fungi.
1) Energy cycles.
2) Food chains.
3) Diversity-inter linkages between organisms.
4) Nutrient cycles-biogeochemical cycles.
5) Evolution
Structural aspects
Functional aspects

• Since each ecosystem has a non-living and a living part that are linked to each other The non-
living components of an ecosystem are the amount of water, the various inorganic substances and
organic compounds, and climatic conditions such as rainfall and temperature, which depend on
geographical conditions and location which is also related to the amount of sunlight. The living
organisms in an ecosystem are inseparable from their habitat.
• The living component of plant life ranges from extremely small bacteria, which live in air, water
and soil, algae which live in fresh and salt water, to the terrestrial plants which range from
grasses and herbs that grow after the monsoon every year, to the giant long-lived trees of the
forest.
• The plants convert energy from sunlight into organic matter for their growth. They thus function
as producers in the ecosystem. The living component of the animal world ranges from
microscopic animals, to small insects and the larger animals such as fish, amphibia, reptiles, birds
and mammals

 Producers, Consumers and Decomposers
• Every living organism is in some way dependent on other organisms. Plants are food for
herbivorous animals which are in turn food for carnivorous animals. Thus there are different
tropic levels in the ecosystem. Some organisms such as fungi live only on dead material and
inorganic matter.

• Plants are the ‘producers’ in the ecosystem as they manufacture their food by using energy from
the sun. In the forest these form communities of plant life. In the sea these include tiny algal
forms to large seaweed.
• The herbivorous animals are primary consumers as they live on the producers. In a forest, these
are the insects, amphibian, reptiles, birds and mammals. The herbivorous animals include for
example Hare(Rabbit), deer and elephants that live on plant life. They graze on grass or feed on
the foliage from trees. In grasslands, there are herbivores such as the blackbuck that feed on
grass. In the semiarid areas, there are species such as the chinkara or Indian gazelle. In the sea,
there are small fish that live on algae and other plants.
blackbuckchinkara or Indian gazelleHare( resembles like Rabbit)
Elephant
Etc..
Herbivorous animals

• At a higher tropic level, there are carnivorous animals, or secondary consumers, which live on
herbivorous animals. In our forests, the carnivorous animals are tigers, leopards, jackals, foxes
and small wild cats. In the sea, carnivorous fish live on other fish and marine animals. Animals
that live in the sea range in size from microscopic forms to giant mammals such as the whale.

 Decomposers or detrivores
These are a group of organisms consisting of small animals like worms, insects, bacteria and
fungi, which break down dead organic material into smaller particles and finally into simpler
substances that are used by plants as nutrition. Decomposition thus is a vital function in nature, as
without this, all the nutrients would be tied up in dead matter and no new life could be produced.

Most ecosystems are highly complex and consist of an extremely large number of individuals of a
wide variety of species. In the species-rich tropical ecosystems (such as in our country), only a
few species are very common, while most species have relatively few individuals. Some species
of plants and animals are extremely rare and may occur only at a few locations. These are said to
be ‘endemic’ to these areas. When human activities alter the balance in these ecosystems, the
“perturbation” leads to the disappearance of these uncommon species. When this happens to an
endemic species that is not widely distributed, it becomes extinct for all time.
Energy flow in the Ecosystem

• Every ecosystem has several interrelated mechanisms that affect human life. These are the water
cycle, the carbon cycle, the oxygen cycle, the nitrogen cycle and the energy cycle. While every
ecosystem is controlled by these cycles, in each ecosystem its abiotic and biotic features are
distinct from each other.
• All the functions of the ecosystem are in some way related to the growth and regeneration of its
plant and animal species. These linked processes can be depicted as the various cycles.
•These processes depend on energy from sunlight. During photosynthesis carbon dioxide is
taken up by plants and oxygen is released. Animals depend on this oxygen for their respiration.
The water cycle depends on the rainfall, which is necessary for plants and animals to live. The
energy cycle recycles nutrients into the soil on which plant life grows. Our own lives are closely
linked to the proper functioning of these cycles of life. If human activities go on altering them,
humanity cannot survive on our earth.

Water Cycle
• When it rains, the water runs along the ground and flows into rivers or falls directly into the sea.
A part of the rainwater that falls on land percolates into the ground. This is stored underground
throughout the rest of the year. Water is drawn up from the ground by plants along with the
nutrients from the soil. The water is transpired from the leaves as water vapor and returned to the
atmosphere. As it is lighter than air, water vapour rises and forms clouds. Winds blow the clouds
for long distances and when the clouds rise higher, the vapour condenses and changes into
droplets, which fall on the land as rain. Though this is an endless cycle on which life depends,
man’s activities are making drastic changes in the atmosphere through pollution which is altering
rainfall patterns.

 Carbon cycle
•The carbon, which occurs in organic compounds, is included in both the abiotic and biotic parts
of the ecosystem. Carbon is a building block of both plant and animal tissues. In the atmosphere,
carbon occurs as carbon dioxide (CO2).

•In the presence of sunlight, plants take up carbon dioxide from the atmosphere through their
leaves. The plants combine carbon dioxide with water, which is absorbed by their roots from the
soil. In the presence of sunlight they are able to form carbohydrates that contain carbon. This
process is known as photosynthesis.
•Plants use this complex mechanism for their growth and development. In this process, plants
release oxygen into the atmosphere on which animals depend for their respiration. Plants
therefore help in regulating and monitoring the percentage of Oxygen and Carbon dioxide in the
earth’s atmosphere. All of mankind thus depends on the oxygen generated through this cycle. It
also keeps the CO2 at acceptable levels. Herbivorous animals feed on plant material, which is
used by them for energy and for their growth. Both plants and animals release carbon dioxide
during respiration. They also return fixed carbon to the soil in the waste they excrete. When
plants and animals die they return their carbon to the soil. These processes complete the carbon
cycle.

 Oxygen Cycle
Oxygen is taken up by plants and animals from the air during respiration. The plants return
oxygen to the atmosphere during photosynthesis. This links the Oxygen Cycle to the Carbon
Cycle. Deforestation is likely to gradually reduce the oxygen levels in our atmosphere. Thus plant
life plays an important role in our lives which we frequently do not appreciate. This is an
important reason to participate in afforestation programs.

Carnivorous animals feed on herbivorous animals that live on plants. When animals defecate,
this waste material is broken down by worms and insects mostly beetles and ants. These small
‘soil animals’ break the waste material into smaller bits on which microscopic bacteria and
fungi can act. This material is thus broken down further into nutrients that plants can absorb and
use for their growth. Thus nutrients are recycled back from animals to plants. Similarly the
bodies of dead animals are also broken down into nutrients that are used by the plants for their
growth. Thus the nitrogen cycle on which life is dependent is completed. closely interlinked to
soil animals, fungi and even bacteria in the soil. When we think of food webs, we usually think
of the large mammals and other large forms of life. But we need to understand that it is the
unseen small animals, plants and microscopic forms of life that are of great value for the
functioning of the ecosystem.

• Ecological succession is a process through which ecosystems tend to change over a period of
time. Succession can be related to seasonal environmental changes, which create changes in the
community of plants and animals living in the ecosystem.
•Other successional events may take much longer periods of time extending to several decades. If
a forest is cleared, it is initially colonized by a certain group of species of plants and animals,
which gradually change through an orderly process of community development. One can predict
that an opened up area will gradually be converted into a grassland, a shrub land and finally a
woodland and a forest if permitted to do so without human interference.
•There is a tendency for succession to produce a more or less stable state at the end of the
successional stages. Developmental stages in the ecosystem thus consist of a pioneer stage, a
series of changes known as serel stages, and finally a climax stage. The successive stages are
related to the way in which energy flows through the biological system. The most frequent
example of successional changes occur in a pond ecosystem where it fluctuates from a dry
terrestrial habitat to the early colonisation stage by small aquatic species after the monsoon,
which gradually passes through to a mature aquatic ecosystem, and then reverts back to its dry
stage in summer where its aquatic life remains dormant

 Food Chain
• The most obvious aspect of nature is that energy must pass from one living organism to
another. When herbivorous animals feed on plants, energy is transferred from plants to animals.
•In an ecosystem, some of the animals feed on other living organisms, while some feed on dead
organic matter. The latter form the ‘detritus’ food chain.
• At each linkage in the chain, a major part of the energy from the food is lost for daily activities.
Each chain usually has only four to five such links. However a single species may be linked to a
large number of species.

 Food Web
In an ecosystem there are a very large number of interlinked chains. This forms a food web. If the
linkages in the chains that make up the web of life are disrupted due to human activities that lead
to the loss or extinction of species, the web breaks down.

 Ecological pyramids
• An ecological pyramid (also trophic pyramid, eltonian pyramid, energy pyramid, or sometimes
food pyramid) is a graphical representation designed to show the biomass or bio productivity at
each trophic level in a given ecosystem.

 Ecosystem goods and services
Direct Values:
These are resources that people depend upon
directly and are easy to measure in economic
terms.
• Consumptive Use Value - Non-market
value of fruit, fodder, firewood, etc.
that are used by people who collect
them from their surrounds.]
• Productive Use Value - Commercial
value of timber, fish, medicinal plants,
etc. that people collect for sale.
Indirect Values
These are uses that do not have easy ways to
quantify them in terms of a clearly definable
price.
• Non-consumptive use value - scientific
research, bird-watching, ecotourism,
etc.
• Option value - maintaining options for
the future, so that by preserving them
one could obtain economic benefits in the
future.
• Existence value - ethical and emotional
aspects of the existence of wildlife and
nature.

 Terrestrial ecosystems
• In their natural state are found in different types of forests, grasslands, semiarid areas, deserts
and sea coasts. Where the land is intensively used, these have been gradually modified over
several thousand years into agricultural and pastoral regions.
•Though this has increased production of food and provides the raw material for ‘consumer’
goods that we use, the overuse and misuse of land and natural ecosystems has led to a serious
degradation of our environment.
•The unsustainable use of environmental goods such as soil, water, fuel wood, timber from forest,
grasses and herbs from grasslands for grazing and repeatedly burning the grass, degrades these
natural ecosystems.
• As industrial ‘development’ led to a very great increase in consumption of resources, the short-
term economic gains for people became an indicator of progress, rather than long term ecological
benefits. This has resulted in an ‘unsustainable use’ of natural resources.

Forest ecosystem
• Forest ecosystem a natural woodland unit consisting of all plants, animals and micro-organisms
(Biotic components) in that area functioning together with all of the non-living physical (abiotic)
factors of the environment.

• The non-living or abiotic aspects of the forest:
The type of forest depends upon the abiotic conditions at the site. Forests on mountains and hills
differ from those along river valleys. Vegetation is specific to the amount of rainfall and the local
temperature which varies according to latitude and altitude. Forests also vary in their plant
communities in response to the type of soil.
• The living or the biotic aspects of the forest:
The plants and animals form communities that are specific to each forest type. For instance
coniferous trees occur in the Himalayas. Mangrove trees occur in river deltas. Thorn trees grow
in arid areas. The snow leopard lives in the Himalayas while the leopard and tiger live in the
forests of the rest of India. Wild sheep and goats live high up in the Himalayas. Many of the birds
of the Himalayan forests are different from the rest of India. Evergreen forests of the Western
Ghats and North East India are most rich in plant and animal species
• The biotic component includes both the large (macrophytes) and the microscopic plants and
animals.
 Plants include the trees, shrubs, climbers, grasses, and herbs in the forest. These include
species that flower (angiosperms), and non-flowering species (gymnosperms) such as ferns,
bryophytes,
fungi and algae.
 The animals include species of mammals, birds, reptiles, amphibians, fish, insects and other
invertebrates and a variety of microscopic animals.

Forest types in India
 The forest type depends upon the abiotic factors such as climate and soil characteristics of a
region. Forests in India can be broadly divided into Coniferous forests and Broadleaved forests.
 They can also be classified according to the nature of their tree species – evergreen,
deciduous, xerophytic or thorn trees, mangroves, etc.
 They can also be classified according to the most abundant species of trees such as Sal or
Teak forests.
Coniferous forests grow in the Himalayan mountain region, where the temperatures are
low. These forests have tall stately trees with needlelike leaves and downward sloping branches
so that the snow can slip off the branches. They have cones instead of seeds and are called
gymnosperms.
Coniferous forests

 Broadleaved forests have several types, such as evergreen forests, deciduous forests, thorn
forests, and mangrove forests. Broadleaved forests have large leaves of various shapes.
Evergreen forests grow in the high rainfall areas of the Western Ghats, North Eastern India and
the Andaman and Nicobar Islands. These forests grow in areas where the monsoon lasts for
several months. Some even get two monsoons, such as in Southern India. Evergreen plants shed a
few of their leaves throughout the year. There is no dry leafless phase as in a deciduous forest. An
evergreen forest thus looks green throughout the year. The trees overlap with each other to form a
continuous canopy. Thus very little light penetrates down to the forest floor. The forest abounds
in animal life and is most rich in insect life.
 Evergreen forests
Evergreen forests

•Deciduous forests are found in regions with a moderate amount of seasonal rainfall that lasts for
only a few months.
•Most of the forests in which Teak trees grow are of this type. The deciduoustrees shed their
leaves during the winter and hot summer months. In March or April they regain their fresh leaves
just before the monsoon, when they grow vigorously in response to the rains. Thus there are
periods of leaf fall and canopy re growth. The forest frequently has a thick undergrowth as light
can penetrate easily onto the forest floor.
Deciduous forests
Deciduous forests

• Thorn forests are found in the semiarid regions of India. The trees, which are densely
distributed, are surrounded by open grassy areas.
•Thorny plants are called xerophytic species and are able to conserve water. Some of these trees
have small leaves, while other species have thick, waxy leaves to reduce water losses during
transpiration.
•Thorn forest trees have long or fibrous roots to reach water at great depths. Many of these plants
have thorns, which reduce water loss and protect them from herbivores.
Thorn forests
Thorn forests

Mangrove forests grow along the coast especially in the river deltas. These plants are able to
grow in a mix of saline and fresh water. They grow luxuriantly in muddy areas covered with silt
that the rivers have brought down. The mangrove trees have breathing roots that emerge from the
mud banks.
Mangrove forests
Mangrove forests

Forest utilization
• Natural forests provide local people with a variety of products if the forest is used carefully.
Over-exploitation for fuel wood or timber, and conversion to monoculture plantations for timber
or other products, impoverishes local people as the economic benefit goes to people who live
elsewhere.
•The entire resource base on which local people have traditionally survived for generations, is
rapidly destroyed. Eventually the forest is completely degraded. Natural forest ecosystems play
an important role in controlling local climate and water regimes.
•It is well-known that under the canopy of a natural forest, it is cooler than outside the forest. The
loss of forest cover in the catchments of a river thus leads to irreversible changes such as
excessive soil erosion, large run-off of surface water during monsoons leading to flash floods,
and a shortage of water once the monsoons are over.

Forest services
•It include the control of the flow of water in streams and rivers. Forest cover reduces surface
runoff of rainwater and allows ground water to be stored.
•Forests prevent erosion of soil. Once soil is lost by erosion, it can take thousands of years to
reform. Forests regulate local temperature. It is cooler and more moist under the shade of the
trees in the forest.
• Most importantly, forests absorb carbon dioxide and release oxygen that we breathe. The wild
relatives of our crop plants and fruit trees have special characteristics in their genes which are
used to develop new crops and newer varieties of fruit.
•These newer varieties developed from wild relatives give greater yields or are more resistant to
diseases. New industrial products are being produced from the wild plants of the forest. Many of
our new medicines come from wild plants
.

What are the threats to the forest ecosystem?
 As forests grow very slowly, we cannot use more resources than they can produce during a
growing season. If timber is felled beyond a certain limit the forest cannot regenerate. The gaps
in the forest change the habitat quality for its animals. The more sensitive species cannot
survive under these changed conditions.
 Over utilizing forest resources is an unsustainable way of misusing our limited forest
resources. We are now creating more and more goods that are manufactured from raw material
from the forest. This leads to forest degradation and finally changes the ecosystem into
wasteland. Wood is illegally extracted from many forests leading to a highly disturbed
ecosystem
 Developmental activities such as rapid population growth together with, urbanization,
industrialization and the increasing use of consumer goods, leads to over utilization of forest
produce. Forests are shrinking as our need for agricultural land increases. It is estimated that
India’s forest cover has decreased from about 33% to 11% in the last century.
 The increasing use of wood for timber, wood pulp for paper and the extensive use of fuel
wood results in continual forest loss. Forests are also lost by mining and building dams. As the
forest resources are exploited beyond what they can produce the forest canopy is opened up, the
ecosystem is degraded, and its wildlife is seriously threatened. As the forest is fragmented into
small patches its wild plant and animal species become extinct. These can never be brought
back. Extinction is forever

 What if the forests disappear?
• When forests are cut down tribal people who depend directly on them for food and fuel wood
and other products find it very difficult to survive.
• Agricultural people do not get enough fuel wood, small timber, etc. for making houses and farm
implements. Urban people who depend on food from agricultural areas, which in turn depend on
neighboring forest ecosystems have to pay a higher price for food as human population grows.
• Insects that live and breed in the forest such as bees, butterflies and moths decrease in
abundance once forests are degraded. As their numbers decrease they are unable to effectively
pollinate agricultural crops and fruit trees. This leads to a decrease in agricultural yields.
•The rain that falls on deforested land flows directly into nearby rivers. Thus water is not retained
under the ground.
•The exposed soil is rapidly washed away during the rains once the protective forest cover is
removed.
•Wild animals lose their habitat. This leads to extinction of our precious species.

How can forest ecosystems be conserved?
We can conserve forests only if we use its resources carefully. This can be done by using
alternate sources of energy instead of fuel wood.
There is a need to grow more trees than are cut down from forests every year for timber.
Afforestation needs to be done continuously from which fuel wood and timber can be
judiciously used.
 The natural forests with all their diverse species must be protected as National Parks and
Wildlife Sanctuaries where all the plants and animals can be preserved

Grassland ecosystems
• A wide range of landscapes in which the vegetation is mainly formed by grasses and small
annual plants are adapted to India’s various climatic conditions. These form a variety of grassland
ecosystems with their specific plants and animals.

 What is a grassland ecosystem?
• Grasslands cover areas where rainfall is usually low and/or the soil depth and quality is poor.
The low rainfall prevents the growth of a large number of trees and shrubs, but is sufficient to
support the growth of grass cover during the monsoon. Many of the grasses and other small herbs
become dry and the part above the ground dies during the summer months. In the next monsoon
the grass cover grows back from the root stock and the seeds of the previous year. This change
gives grasslands a highly seasonal appearance with periods of increased growth followed by a
dormant phase.
•A variety of grasses, herbs, and several species of insects, birds and mammals have evolved so
that they are adapted to these wide-open grass covered areas. These animals are able to live in
conditions where food is plentiful after the rains, so that they can store this as fat that they use
during the dry period when there is very little to eat.

Grassland Types in India:
Himalayan pasture belt
• The Himalayan pasture belt extends up to the snowline. The grasslands at a lower level form
patches along with coniferous or broadleaved forests. Himalayan wildlife require both the forest
and the grassland ecosystem as important parts of their habitat. The animals migrate up into the
high altitude grasslands in summer and move down into the forest in winter when the snow
covers the grassland. These Himalayan pastures have a large variety of grasses and herbs.
Himalayan hill slopes are covered with thousands of colorful flowering plants. There are also a
large number of medicinal plants.
Himalayan pasture belt

Terai grassland
The Terai consists of patches of tall grasslands interspersed with a Sal forest ecosystem. The
patches of tall elephant grass, which grows to a height of about five meters, are located in the
low-lying waterlogged areas. The Sal forest patches cover the elevated regions and the
Himalayan foothills. The Terai also includes marshes in low-lying depressions. This ecosystem
extends as a belt south of the Himalayan foothills.
Terai grassland

 Semiarid grassland
The Semi-arid plains of Western India, Central India and the Deccan are covered by grassland
tracts with patches of thorn forest. Several mammals such as the wolf, the blackbuck, the
chinkara, and birds such as the bustards and floricans are adapted to these arid conditions. The
Scrublands of the Deccan Plateau are covered with seasonal grasses and herbs on which its fauna
is dependent. It is teaming with insect life on which the insectivorous birds feed.
Semiarid grassland

 Shola grassland
• The Shola grasslands consist of patches on hill slopes along with the Shola forests on
theWestern Ghats, Nilgiri and Annamalai ranges. This forms a patchwork of grassland on the
slopes and forest habitats along the streams and low-lying areas.
Shola grassland

 What are the threats to grassland ecosystems?

 How can grassland ecosystems be conserved?

What should we do?
• There is a need to preserve the few natural grassland areas that still survive by creating
National Parks and Wildlife Sanctuaries in all the different types of grasslands.
• Animals such as the wolf, blackbuck, chinkara and birds such as bustards and floricans
have now become rare all over the country. They must be carefully protected in the few
National Parks and Wildlife Sanctuaries that have natural grassland habitats as well as
outside these Protected Areas.
• We need to create an awareness among people that grasslands are of great value. If we are
all concerned about our disappearing grasslands and their wonderful wildlife, the
Government will be motivated to protect them.
• Keeping grasslands alive is a National priority.

Desert ecosystem
Desert is an arid region characterized by a extremely high and low temperature and has
scares of vegetation.

• Deserts and semi arid areas are located in Western India and the Deccan Plateau. The climate in
these vast tracts is extremely dry.
•There are also cold deserts such as in Ladakh, which are located in the high plateaus of the
Himalayas.
Cold deserts such as in Ladakh

•The most typical desert landscape that is seen in Rajasthan is in the Thar Desert. This has sand
dunes. There are also areas covered with sparse grasses and a few shrubs, which grow if it rains.
In most areas of the Thar the rainfall is scanty and sporadic. In an area it may rain only once
every few years. In the adjoining semi arid tract the vegetation consists of a few shrubs and
thorny trees such as kher and babul.
Rajasthan is in the Thar Desert
Sand Dunes or Sand Waves

The Great and Little Rann of Kutch are highly specialised arid ecosystems. In the summers they
are similar to a desert landscape. However as these are low-lying areas near the sea, they get
converted to salt marshes during the monsoons. During this period they attract an enormous
number of aquatic birds such as ducks, geese, cranes, storks, etc. The Great Rann is famous, as it
is the only known breeding colony of the Greater and Lesser Flamingos in our country. The Little
Rann of Kutch is the only home of the wild ass in India. Desert and semi arid regions have a
number of highly specialized insects and reptiles. The rare animals include the Indian wolf, desert
cat, desert fox and birds such as the Great Indian Bustard and the Florican. Some of the
commoner birds include partridges, quails and sandgrouse
.
Summer season
Monsoon season

Flamingos Wild ass
Indian wolf Indian Bustard

How are desert and semi-arid ecosystems used?
Areas of scanty vegetation with semi-arid scrubland have been used for camel, cattle and goat
grazing in Rajasthan and Gujarat, and for sheep grazing in the Deccan Plateau. Areas that have a
little moisture, such as along the watercourses, have been used for growing crops such as jowar,
and bajra. The natural grasses and local varieties of crops have adapted to growing at very low
moisture levels

What are the threats to desert ecosystems?

•Desert ecosystems are extremely sensitive. Their ecological balance that forms a habitat for their
plants and animals is easily disturbed. Desert people have traditionally protected their insufficient
water resources.
•The Bishnois in Rajasthan are known to have protected their Khejdi trees and the blackbuck
antelope for several generations.
•The tradition began when the ruler of their region ordered his army to cut down trees for his own
use. Several Bishnois were said to have been killed while trying to protect their trees. There is an
urgent need to protect residual patches of this ecosystem within National Parks and Wildlife
Sanctuaries in desert and semi arid areas.
•The Indira Gandhi Canal in Rajasthan is destroying this important natural arid ecosystem, as it
will convert the region into intensive agriculture. In Kutch, areas of the little Rann, which is the
only home of the Wild Ass, will be destroyed by the spread of salt works.
•Development Projects alter the desert and arid landscape. There is a sharp reduction in the
habitat available for its specialised species bringing them to the verge of extinction. We need a
sustainable form of development that takes the special needs of the desert into account.
How can desert ecosystems be conserved?
Bishnois Khejdi tree

 Aquatic ecosystem
An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are
dependent on each other and on their environment live in aquatic ecosystems. The two main
types of aquatic ecosystems are marine ecosystems and fresh water ecosystems.

Types of Aquatic ecosystems
• The aquatic ecosystems are classified into freshwater, brackish and marine ecosystems, which
are based on the salinity levels.
•The fresh water ecosystems that have running water are streams and rivers.
• Ponds, tanks and lakes are ecosystems where water does not flow.
•Wetlands are special ecosystems in which the water level fluctuates dramatically in different
seasons. They have expanses of shallow water with aquatic vegetation, which forms an ideal
habitat for fish, crustacea and water birds.
•Marine ecosystems are highly saline, while brackish areas have less saline water such as in river
deltas.

• Coral reefs are very rich in species and are found in only a few shallow tropical seas. The
richest coral reefs in India are around the Andaman and Nicobar islands and in the gulf of Kutch.
• Brackish water ecosystems in river deltas are covered by mangrove forests and are among the
world’s most productive ecosystems in terms of biomass production. The largest mangrove
swamps are in the Sunderbans in the delta of the Ganges.
Coral reefs Brackish water ecosystems

•The pond is the simplest aquatic ecosystem to observe. There are differences in a pond that is
temporary and has water only in the monsoon, and a larger tank or lake that is an aquatic
ecosystem throughout the year. Most ponds become dry after the rains are over and are covered
by terrestrial plants for the rest of the year.
•When a pond begins to fill during the rains, its life forms such as the algae and microscopic
animals, aquatic insects, snails, and worms come out of the floor of the pond where they have
remained dormant in the dry phase. Gradually more complex animals such as crabs frogs and fish
return to the pond.
 Pond ecosystem

• The vegetation in the water consists of floating weeds and rooted vegetation on the periphery
which grow on the muddy floor under water and emerge out of the surface of the water.
• As the pond fills in the monsoon a large number of food chains are formed. Algae is eaten by
microscopic animals, which are in turn eaten by small fish on which larger carnivorous fish
depend. These are in turn eaten by birds such as kingfishers, herons and birds of prey. Aquatic
insects, worms and snails feed on the waste material excreted by animals and the dead or
decaying plant and animal matter. They act on the detritus, which is broken down into nutrients
which aquatic plants can absorb, thus completing the nutrient cycle in the pond. The temporary
ponds begin to dry after the rains and the surrounding grasses and terrestrial plants spread into the
moist mud that is exposed. Animals such as frogs, snails and worms remain dormant in the mud,
awaiting the next monsoon.

 Lake ecosystem
• A lake ecosystem functions like a giant permanent pond. A large amount of its plant material is
the algae, which derives energy from the sun. This is transferred to the microscopic animals,
which feed on the algae. There are fish that are herbivorous and are dependent on algae and
aquatic weeds. The small animals such as snails are used as food by small carnivorous fish,
which in turn are eaten by larger carnivorous fish. Some specialized fish, such as catfish, feed on
the detritus on the muddy bed of the lake.

Energy cycles through the lake ecosystem from the sunlight that penetrates the water surface to
the plants. From plants energy is transferred to herbivorous animal and carnivores. Animals
excrete waste products, which settle on the bottom of the lake. This is broken down by small ani-
mals that live in the mud in the floor of the lake. This acts as the nutrient material that is used by
aquatic plants for their growth. During this process plants use Carbon from CO2 for their growth
and in the process release Oxygen. This Oxygen is then used by aquatic animals, which filter
water through their respiratory system.

 Stream and River ecosystem
Stream River

• Some species of fish, such as Mahseer, go upstream from rivers to hill streams for breeding.
They need crystal clear water to be able to breed. They lay eggs only in clear water so that their
young can grow successfully.
•As deforestation occurs in the hills the water in the streams that once flowed throughout the year
become seasonal. This leads to flash floods in the rains and a shortage of water once the streams
dry up after the monsoon. The community of flora and fauna of streams and rivers depends on the
clarity, flow and oxygen content as well as the nature of their beds. The stream or river can have a
sandy, rocky or muddy bed, each type having its own species of plants and animals.
Mahseer

 Marine ecosystems
Marine ecosystems are among the largest of Earth's aquatic ecosystems. Examples include salt
marshes, intertidal zones, estuaries, lagoons, mangroves, coral reefs, the deep sea, and the sea
floor. They can be contrasted with freshwater ecosystems, which have a lower salt content.

• The Indian Ocean, the Arabian Sea and the Bay of Bengal constitute the marine ecosystems
around peninsular India.
•The producers in this ecosystem vary from microscopic algae to large seaweeds. There are
millions of zooplankton and a large variety of invertebrates on which live fish, turtles and marine
mammals.
•The shallow areas near Kutch and around the Andaman and Nicobar Islands are some of the
most incredible coral reefs in the world. Coral reefs are only second to tropical evergreen forests
in their richness of species. Fish, crustacea, starfish, jellyfish and the polyps that deposit the coral
are a few of the thousands of species that form this incredible world under the shallow sea.
Crustaceans form a large, diverse arthropod taxon which
includes such familiar animals as crabs, lobsters, crayfish,
shrimp, krill, woodlice and barnacles.
Star fish

•The marine ecosystem is used by coastal fisher folk for fishing which forms their livelihood. In
the past, fishing was done at a sustainable level.
•The marine ecosystem continued to maintain its abundant supply of fish over many generations.
Now with intensive fishing by using giant nets and mechanized boats, fish catch in the Indian
Ocean has dropped significantly.

Seashore ecosystems
•Beaches can be sandy, rocky, shell covered or muddy. On each of these different types, there are
several specific species which have evolved to occupy a separate niche. There are different
crustacean such as crabs that make holes in the sand.
•Various shore birds feed on their prey by probing into the sand or mud on the sea shore. Several
different species of fish are caught by fishermen. In many areas the fish catch has decreased
during the last decade or two.

Module 3 ENVIRONMENT AND ECOLOGY _VTU

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Module 3 ENVIRONMENT AND ECOLOGY _VTU