ECOSYSTEM
Ecosystem. Eco=Environment. System=Web of interaction
An ecosystem is a community of organisms involved in a dynamic network
of biological, chemical and physical interactions between themselves and
with the non-living components.
Such interactions are crucial for sustaining the system and allowing it to
respond to changing conditions.
An ecosystem is also defined as a functional and structural unit of Ecology.
This implies that each ecosystem has a definite structure and components, and
that each component part of the system has a definite role to play in the
functioning of the ecosystem.
Unlike ecological communities which comprise of living elements only,
ecosystems have two ‘parts’: The living (biotic) components like plants and
animals; and the non-living (abiotic) components like water, air, nutrients and
solar energy.
These two parts of the ecosystem do not stand in isolation, rather they
continuously interact with one another. In fact they are so closely linked to
each other.
Difference between ECOLOGY and ECOSYTEM
Ecology is the study of ecosystems and the environment while the Ecosystem is
a unit of ecology that addresses both BIOTIC and ABIOTIC components of a
community.
Ecology is the study of relationships and interactions of living organisms either
with other living organisms or the surrounding environment.
Ecosystem is a subpart of ecology. It comprises of a biotic factor including all
animals, plants, and microorganisms, and an abiotic factor including all non-living
physical factors in the environment.
The main difference between ecology and ecosystem is that ecology is the
study of ecosystems whereas ecosystems are units that are formed by the
interaction of a community of organisms with the environment.
ECOSYSTEM
An ecosystem is made up of all the living and non-living things in an environment.
An ecosystem is a natural unit consisting of all plants, animals and micro-organisms (biotic factors) in an area
functioning together with all of the non-living physical (abiotic) factors of the environment.
It is an interaction between BIOTIC and ABIOTIC components.
1. Abiotic: (Non-living things) namely – Air, Rocks, Soil, Cave, Water…
The abiotic environmental components include basic inorganic elements and compounds such as water and carbon
dioxide, calcium and oxygen, carbonates and phosphates besides such physical factors as soil, rainfall, temperature,
moisture, winds, currents, and solar radiation with its concomitants of light and heat.
Non-living things in a ecosystem can include water, air, soil, and light. Non-living things help the living things meet
their needs.
2. Biotic: (Living things) namely – Fish, water-lilly, plants, animals, people.
The biotic environmental factors comprise plants, animals, and microbes; They interact in a fundamentally energy-
dependent fashion. In the words of Helena Curtis “The scientific study of the interactions of organisms with their
physical environment and with each other, is called ecology”. According to Herreid II “It mainly concerns with the
directive influences of abiotic and biotic environmental factors over the growth, distribution behaviour and survival
of organisms.
Living components
Living organisms (biotic components) in an ecosystem can be classified as either producers or consumers,
depending on how they get their food.
Producers (autotrophs, i.e. self-feeders) can make the organic nutrients they need, using simple inorganic
compounds in their environment: for instance, the green plants on land and the small algae in aquatic ecosystems
produce their food by the process of photosynthesis.
Consumers (heterotrophs, i.e. otherfeeders) are those organisms, which directly or indirectly depend on food
provided by producers. Consumers, depending on their food habits, can be further classified into four types.
Herbivores,e.g. deer, rabbits, cattle, etc., are plant eaters and they feed directly on producers. In a food
chain, they are referred to as the primary consumers.
Carnivores are meat eaters and they feed on herbivores (primary consumers). They are thus known as
secondary consumers. They are animal eaters, e.g. lions, tigers.
Omnivores eat both plants and animals, e.g. pigs, rats, cockroaches and humans.
Decomposers digest the complex organic molecules in dead organic matter (detritus) into simpler inorganic
compounds. They absorb the soluble nutrients as their food. Some examples are bacteria, fungi, and mites.
What is important to note is that each ecosystem will have certain representative organisms playing each of the
above mentioned roles.
Non-living components
Non-living (or abiotic) components of an ecosystem include all the physical and
chemical factors that influence living organisms, like air, water, soil, rocks etc. Thus, it is
an assemblage of organic and inorganic substances present in an ecosystem. The
various climatic factors that affect the ecosystem functioning are also a part of this. The
non-living components are essential for the living world. Without sunlight, water, air and
minerals, life cannot exist.
All organisms play a role in their ecosystem:
Decomposers
Break down waste and dead organisms to return raw materials to the
environment
• Ex: bacteria, fungi, worms
DECOMPOSERS
Decomposers are organisms that break down dead organic material and wastes.
Decomposers (primarily bacteria, fungi; nematodes like tapeworms; mites and certain insects)
are organisms that feed by degrading organic matter.
Decomposers are sometimes considered their own trophic level. As a group, they eat dead
matter and waste products that come from organisms at various other trophic levels; for
instance, they would happily consume decaying plant matter, the body of a half-eaten
squirrel, or the remains of a deceased eagle.
Fungi and bacteria are the key decomposers in many ecosystems; they use the chemical
energy in dead matter and wastes to fuel their metabolic processes. These are usually
multicellular animals such as earthworms, crabs, slugs, or vultures. They not only feed on
dead organic matter but often fragment it as well, making it more available for bacterial or
fungal decomposers.
Decomposers are essential components of all nutrient cycles and food chains. Decomposers
break down organic waste and recycle the nutrients present in it.
If decomposers are removed from the biosphere, the earth will become a vast dump of dead
organisms.
Life will probably stop, as the nutrients for life would be tied up in the dead organisms.
Earthworms
Tapeworms
Food Chain
Food chain – shows one path of the flow of energy in an ecosystem. It describes the feeding relationship
between a producer and a single chain of consumers in an ecosystem.
The transfer of energy from sun to producer to primary consumer to secondary consumer to tertiary consumer
can be shown in a FOOD CHAIN.
A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats
another. This feeding relationship in an ecosystem is called a food chain.
Food chains are usually in a sequence, with an arrow used to show the flow of energy.
All living things need to feed to get energy to grow, move and reproduce.
What do these living things feed on? Smaller insects feed on green plants, and bigger animals feed on smaller ones and so
on.
Order of the food chain:
1.Sun – energy source
2.Producer
3.1st level Consumer – eats producers
4.2nd level Consumer – eats 1st level consumers
5.Decomposer – recycles materials for use by producers
The sun is the source of all the energy in food chains. Green plants, usually the
first level of any food chain, absorb some of the Sun’s light energy to make their
own food by photosynthesis. Green plants (autotrophs) are therefore known as
‘Producers’ in a food chain.
At the base of the food chain lie the primary producers. The primary producers
are autotrophs and are most often photosynthetic organisms such as plants, algae,
or cyanobacteria.
The organisms that eat the primary producers are called primary consumers.
Primary consumers are usually herbivores, plant-eaters, though they may be
algae eaters or bacteria eaters.
The organisms that eat the primary consumers are called secondary consumers.
Secondary consumers are generally meat-eaters—carnivores.
The organisms that eat the secondary consumers are called tertiary consumers.
These are carnivore-eating carnivores, like eagles or big fish.
Some food chains have additional levels, such as quaternary consumers—
carnivores that eat tertiary consumers. Organisms at the very top of a food chain
are called apex consumers.
At the top of the levels are Predators. They are animals that have little or no
natural enemies. They are the ‘bosses’ of their ecosystems. Predators feed on preys.
A prey is an animal that predators hunt to kill and feed on. Predators include owls,
snakes, wild cats, crocodiles and sharks. Humans can also be called predators.
When any organism dies, detrivores (like vultures, worms and crabs) eat them up.
The rest are broken down by decomposers (mostly bacteria and fungi), and the
exchange of energy continues. Decomposers start the cycle again.
FOOD CHAINS
who
Food Chain: is a sequence of feeding relationships describing ______
eats whom .
_________
Sun is the source
The ____ of energy for
______________
food chains.
eagle
Keep in mind that the arrow
tip always points towards the
snake “eater”.
eater
frog
grass-
hopper
grass food
1. FOOD CHAIN IN THE FOREST
ECOSYSTEM
There are different levels
of consumers…..
eagle
cannot make
Since they _______
their own food, they must snake
consume other
eat or “________”
organisms.
frog
basis of all
They form the _____
terrestrial grass-
________ food chains.
hopper
They use the energy in
sunlight
_______ to make their grass
own food through a process
photosynthesis
called _____________.
FOOD CHAINS Top carnivore: any organism that is
There are different levels of __________ top
not hunted by any other. It’s at the ___
consumers….. of its food chain.
eagle quaternary consumer
The ___
4th consumer in a food chain.
It eats tertiary
________________.
consumers
snake tertiary consumer
The 3rd
___ consumer in a food chain.
It eats secondary consumers
__________________.
frog secondary consumer
The 2nd
___ consumer in a food chain.
It eats primary
________________.
consumers
grass-
primary consumer
hopper 1st consumer in a food chain.
The ___
producers
It eats _________.
grass
FOOD CHAINS All organisms eventually die and decompose.
eagle Detritus: is the waste
___________
matter
and _____________
rotting remains of dead
organisms.
snake
Decomposers: are
frog eat
detritus organisms that ___
detritus and break
_______
grass- it down into
hopper nutrients
________.
decomposers
grass
Nutrients: are substances
needed for an organism’s
The cycle restarts. nutrients ______
growth and _____.
repair
FOOD CHAIN IN THE AQUATIC ECOSYSTEM
aquatic ecosystems.
Food chains can occur in _______
FOOD CHAINS top carnivore
killer whale
Marine food chains
start with microscopic
shark
aquatic organisms called
phytoplankton that can
_____________
larger fish photosynthesis
perform _____________
to make their own food.
small fish
zooplankton
phytoplankton
aquatic ecosystems.
Food chains can occur in _______
FOOD CHAINS
Though most aquatic food chains
start off with photosynthetic
AQUATIC ECOSYSTEM
phytoplankton that get their
energy from the sun, there are
exceptions.
In the 1970s, scientists discovered
deep sea _________________
hydrothermal vents in
the ocean which were too deep
sunlight to reach.
for _______
Chemoautotrophic Bacteria Here they found new types of
in Hydrothermal Vents bacteria that could generate
_______
sulfides found in
energy using the _______
How could a food the vents. They didn’t need the
chain start without sunlight sun
___ for energy.
and photosynthesis?
EXAMPLES OF DIFFERENT FOOD CHAIN
HUMANS AND FOOD CHAINS
Have you ever eaten one of these? What food chains did you
What is it made of? participate in when you ate this?
wheat tomato mutton
cheese onion
lettuce
HUMANS AND FOOD CHAINS
Since humans are not hunted for food by any other animal,
and since humans eat almost anything, (well maybe not this)
this makes us
top carnivores
____________.
Where are humans on
any food chain?
?
Count how many of these
animals you’ve eaten in
your life.
FOOD WEB
FOOD WEB
Food chains give us a clear-cut picture of who eats whom. It
shows how energy is transferred from one living organism to
another via food
For instance, an organism can sometimes eat multiple
types of prey or be eaten by multiple predators,
including ones at different trophic levels.
BUT, a food web is a model that shows the energy flow
through different organisms in an ecosystem. It consists of
many overlapping food chains in an ecosystem
In fact Food Web is an interconnected food chains. They
show the feeding relationships in an ecosystem
THE DIFFERENCE
FOOD WEB VS FOOD CHAIN
• The difference between Food Chain and Food Web:
ENERGY FLOW
ENERGY FLOW IN TROPHIC LEVELS
As organisms eat one another,energy
______ is
transferred up the food chain.
eagle 0.1 kcal However, as energy is moved from one
10 % of the
trophic level to the next, only ___
- 0.9 kcal
energy makes it to the next level.
snake 1 kcal
- 9 kcal
This 10 % is used to build biomass
_______
frog 10 kcal bodily functions
as well as to fuel ______________.
- 90 kcal
grass- 90 of the energy is
This means that ___%
100 kcal lost, mostly in the form of
hopper
- 900 kcal detritus and as heat
_______ ____ from metabolic
processes.
grass 1000 kcal
Flow of energy
When an organism eats, it obtains energy, then uses a lot of energy in life
process like growth and movement.
This means that only part of their energy is available to the next organism in the
food web.
Some of the energy is lost as heat, but some energy is stored and can passed on
to another consumer
Energy Pyramid
Illustrates the amount of energy that moves
from one feeding level to another in a food
chain or web
That the amount of available energy
decreases down the food chain
It takes a large number of producers to
support a small number of primary consumers
It takes a large number of primary consumers
to support a small number of secondary
consumers
The greatest amount of energy is available at
the producer level
The least amount of energy available to going to be a
the top of the food chain.
Only about 10% of the trophic level’s energy
is transferred to the next level.
STRUCTURE AND FUNCTION OF AN
ECOSYSTEM
Ecosystem Structure – The vertical and horizontal distribution of ecosystem components
(e.g., vegetation, distribution of plant biomass above and below ground, etc.). It is an
organisation of biotic and abiotic components within the ecosystem.
POPULATION, COMMUNITY, HABITAT
A group of organisms of the same kind living in the same place is a population.
All the population that live in an ecosystem at the same time form a
community. All members of a community live in the same ecosystem but they
do not all live in the same part of the ecosystem.
Habitat is a place where plants and animals lives. It is a place where they can
meet their needs. Animals get food, water, and shelter from their habitat. Some
organisms can survive only in certain habitats. For example, a polar could not
find the water it needs in a desert.
ECOLOGY AND ECOSYSTEM
Ecology Defined:
1. Taylor (1936) defines ecology as “the science of the relations of all organisms to all their environments.”
2. G.L. Clarke (1954) defined ecology as “the study of inter-relations of plants and animals with their
environment which may include the influences of other plants and animals present as well as those of the
physical features.”
3. R.L. Smith (1977), considers ecology as “a multidisciplinary science which deals with the organism and its
place to live and which focuses on the ecosystems.”
ECO-SYSTEM
At present ecological studies are made at Eco-system level. At this level the units of study are quite large. This
approach has the view that living organisms and their non-living environment are inseparably interrelated and
interact with each other. A.G. Tansley (in 1935) defined the Eco-system as ‘the system resulting from the
integrations of all the loving and non-living actors of the environment’. Thus he regarded the Eco-systems as
including not only the organism complex but also the whole complex of physical factors forming the
environment.
1. The terms ecosystems is most preferred, where ‘eco’ implies the environment, and ‘system’ implies an
interacting, inter-dependent complex.
Division of Ecosystem
The ecosystem can be divided, from the energetic view point into three types of
organisms:
producers, consumers, and reducers. These can be explained as under:
(1) Producer
Photosynthetic algae, plants and bacteria are the producers of the ecosystem; all
other organisms depend upon them directly or indirectly for food.
(2) Consumers
Consumers are herbivorous, carnivorous, and omnivorous animals; they eat the
organic matter produced by other organisms.
(3) Reducers / Decomposers
Reducers are heterotrophic organisms like animals; they are fungi and bacterial
that decompose dead organic matter.
PRODUCERS AND CONSUMERS
PRODUCERS: Producers are also called “autotrophs” which means self-feeders, because they make their own food.
In other words, plants perform a complex set of chemical reactions called photosynthesis.
Producers provide energy for other organisms in an ecosystem.
Producers get their energy from non-living resources.
Producers are also called autotrophs because they make their own food.
Producers provide energy for other organisms in an ecosystem.
CONSUMERS: Organisms that eat plants are called primary consumers.
Consumers are organisms that get their energy by eating other living or once-living resources.
Consumers are also called heterotrophs because they feed off of different things.
Primary consumers are herbivores – the only eat plant material.
Primary consumers are right above plants in any given food chain
Secondary consumers are those that eat primary consumers, tertiary consumer secondary and so on…
These consumers are either carnivores (sometimes insectivores or egg eaters), or ominvores
Almost all producers obtain energy from sunlight.
Photosynthesis in most producers uses sunlight as an energy source.
Chemosynthesis in prokaryote producers uses chemicals as an energy source.
PRODUCERS AND CONSUMERS
Consumers are not all alike:
Herbivores eat only plants.
Carnivores eat only animals.
Omnivores eat both plants and animals.
Detritivores eat dead organic matter.
Decomposers are detritivores that break down organic matter into simpler
compounds.
Scavengers : are animals that do not kill for a meal, but pick on “leftovers” from other animals
Hyenas, vultures, crows, racoons, and some bears are scavengers.
Decomposers: Decomposers or detritivores are organisms that degrade or decompose dead or
organic material in simpler molecules Fungi and bacteria are decomposers
The Forest Ecosystems
They are the ecosystems in which an abundance of flora, or plants, is seen
so they have a big number of organisms which live in relatively small space.
Therefore, in forest ecosystems the density of living organisms is quite high. A
small change in this ecosystem could affect the whole balance, effectively
bringing down the whole ecosystem. You could see a fantastic diversity in the
fauna of the ecosystems, too.
The Desert Ecosystem
Desert ecosystems are located in regions that receive an annual rainfall less than 25%. They occupy about 17 percent of all
the land on our planet. Due to the extremely high temperature, low water availability and intense sunlight, fauna and flora
are scarce and poorly developed.
The vegetation is mainly shrubs, bushes, few grasses and rare trees. The stems and leaves of the plants are
modified in order to conserve water as much as possible. The best known desert ones are the succulents
such as the spiny leaved cacti. The animal organisms include insects, birds, camels, reptiles all of which are
adapted to the desert conditions.
.
The Grassland Ecosystem
Grasslands are located in both the tropical and temperate regions of the world though the
ecosystems vary slightly. The area mainly comprises grasses with a little number of trees and
shrubs. The main vegetation includes grasses, plants and legumes that belong to the
composite family. A lot of grazing animals, insectivores and herbivores inhabit the grasslands
The Mountain Ecosystem
Mountain land provides a scattered and diverse array of habitats where a large
number of animals and plants can be found. At the higher altitudes, the harsh
environmental conditions normally prevail, and only the treeless alpine vegetation
can survive. The animals that live there have thick fur coats for prevention from
cold and hibernation in the winter months. Lower slopes are commonly covered
with coniferous forests.
Aquatic Ecosystems
The aquatic ecosystem is the ecosystem found in a body of water. It
encompasses aquatic flora, fauna and water properties, as well. There are two
main types of aquatic ecosystem - Marine and Freshwater.
The Marine Ecosystem
Marine ecosystems are the biggest ecosystems, which cover around 71% of Earth's surface and contain 97% of out
planet's water. Water in Marine ecosystems features in high amounts minerals and salts dissolved in them.
Contrary to the Marine ecosystems, the freshwater ecosystem covers only 0.8% of Earth's surface and contains 0.009% of the
total water. Three basic kinds of freshwater ecosystems exist:
Lentic: Slow-moving or till water like pools, lakes or ponds.
Lotic: Fast-moving water such as streams and rivers.
Wetlands: Places in which the soil is inundated or saturated for some lengthy period of time.
The ecosystems are habitats to reptiles, amphibians and around 41% of the world’s fish species. The faster moving turbulent
waters typically contain a greater concentrations of dissolved oxygen, supporting greater biodiversity than slow moving waters
in pools.
LITHOSPHERE
• The earth is roughly 4.5 billion years old
• It is the third planet orbiting around the sun
• It is the only planet in our solar system to
have surface liquid water
• It is home to the only known life in the
universe
• The Lithosphere is always in motion, but it is
very gradual and usually takes hundreds to
thousands of years to notice. The movement
of the Earth's crust is known as PLATE
TECHTONICS. Again, we'll get more into
detail 2nd semester with that.
Internal Structure of Earth
Lithosphre Comprises the Earth’s crust and
part of the upper mantle.
The Word ‘Litho’ means Rock.
A rock is a heterogeneous blend of various
grains (each grain is a mineral)
A mineral is a pure, natural and inorganic
substance
LITHOSPHERE
The lithosphere (geosphere) is the "solid" part of Earth.
It has two parts, the crust and the upper mantle
The lithosphere “ sits on the” asthenosphere.
The Earths Plates are the lithosphere.
It is the rocky, solid portion of the crust. Remember that it is made up of mostly Silicon( Si)
and Oxygen (O). Earth’s crust is broken into about 19 pieces
These plates move on top of the asthenosphere
The land that makes up all the continents on earth is called
CONTINENTAL CRUST. It is pretty thick, like 40-50 kilometers.
BIOSHPHERE
• The biosphere is the “life zone” of the Earth,
and includes all living organisms (including
humans), and all organic matter that has not
yet decomposed.
• The biosphere is structured into a hierarchy
known as the food chain (all life is dependent on
the first tier – mainly the primary producers
that are capable of photosynthesis).
• Energy and mass is transferred from one level
of the food chain to the next.
• The Word “Bio” means living, so the biosphere
includes ALL LIVING THINGS on Earth.
• All types of organisms are included: Archaea,
Bacteria, Protists, Fungi, Plants, Animals.
The Biosphere is made up of 3 parts
• Atmosphere (air)
• Hydrosphere (water)
• Lithosphere (rock and sediments)
Biosphere Consists of the following:
1. Ecosystems
Habitat - where an organism lives, its environment
Niche - interactions of an organism with its habitat
Ecosystem - habitat, niche and interactions between
organisms
2. Energy
Sun plants animals
First Law of Thermodynamics energy cannot be
destroyed or created, just changes form
3. Water cycle : Water evaporation, cloud formation,
precipitation….
4. Nutrients and minerals recycled
Most plants require 17 elements
Composition of life (95%) is Carbon, Oxygen, Hydrogen,
Nitrogen, Phosphorous, and Sulfur.
Elements and minerals necessary for animal functions
5. Food chain
HYDROSPHERE
The Hydrosphere is ALL THE WATER on the planet Earth.
Most (as in 97% or more) of Earth's water is in the Oceans. Most of the freshwater on Earth is frozen in glaciers and ice caps.
Only a super tiny fraction of Earth's water makes up lakes + rivers.
Earth's water is always transferring from place to place known as Water Cycle.
Water found on the surface of our planet includes the ocean as well as water from lakes and rivers, streams, and creeks.
Water found under the surface of our planet includes water trapped in the soil and groundwater.
Water found in our atmosphere includes water vapor.
Frozen water on our planet includes ice caps and glaciers.
Only about 3% of the water on Earth is “fresh” water, and about 70% of the fresh water is frozen in the form of glacial ice.
The water of the seas and oceans is salty because of the vast quantity of mineral salts dissolved in it.
ISSUES RELATED TO BIODIVERSITY
What is Biodiversity?
Biodiversity is the variety of life on Earth and the essential interdependence of all living things
It deals with the degree of nature’s variety in the biosphere.
This variety can be observed at three levels:
1. The genetic variability within a species
2. Species Diversity
3. Ecosystem Diversity
1. GENETIC DIVERSITY:
Each member of any animal or plant species differs widely from other individuals in its genetic makeup
because of the large number of combinations possible in the genes that give every individual specific characteristics.
Example: Each human being is very different from all others.
This genetic variability is essential for a healthy breeding population of a species.
If the number of breeding individuals is reduced the extinction of the species begins.
Today the variety of nature’s bounty is being further harnessed by using wild relatives of crop plants to create
new varieties of more productive crops and to breed better domestic animals.
Modern biotechnology manipulates genes for developing better types of medicines and a variety of industrial
products.
2. Species diversity:
The number of species of plants and animals that are present in a region constitutes its species
diversity.
This diversity is seen both in natural ecosystems and in agricultural ecosystems.
Some areas are more rich in species than others. Example: Natural undisturbed tropical forests have a
much greater species richness than plantations developed by the Forest Department for timber
production.
A natural forest ecosystem provides a large number of non-wood products that local people depend on
such as fruit, fuel wood, fodder, fibre, gum, resin and medicines.
Timber plantations do not provide the large variety of goods that are essential for local consumption.
Thus the value of a natural forest, with all its species richness is much greater than a plantation.
Modern intensive agricultural ecosystems have a relatively lower diversity of crops than traditional
agro pastoral farming systems where multiple crops were planted.
At present conservation scientists have been able to identify and categorise about 1.8 million species
on earth. However, many new species are being identified, especially in the flowering plants and
insects. Areas that are rich in species diversity are called ‘hotspots’ of diversity.
India is among the world’s 15 nations that are exceptionally rich in species diversity.
3. Ecosystem diversity:
Distinctive ecosystems include land scales such as forests, grasslands, deserts,
mountains, etc., as well as aquatic ecosystems such as rivers, lakes, and the sea.
Each region also has man-modified areas such as farmland or grazing pastures.
An ecosystem is referred to as ‘natural’ when it is relatively undisturbed by
human activities, or ‘modified’ when it is changed to other types of uses, such as
farmland or urban areas.
Ecosystems are most natural in wilderness areas. If natural ecosystems are
overused or misused their productivity eventually decreases and they are then
said to be degraded. India is exceptionally rich in its ecosystem diversity.
Direct Use Value of Biodiversity: Goods
Food
Building Materials
Fuel
Paper Products
Fiber (clothing, textiles)
Industrial products (waxes, rubber, oils)
Medicine
Source: © AMNH-CBC
Indirect Use Values of Biodiversity: Services
Regulating global processes, such as
atmosphere and climate
Soil and water conservation
Nutrient cycling
Pollination and seed dispersal
Control of agricultural pests
Genetic library
Inspiration and information
Scientific and educational
Tourism and recreation
Cultural, spiritual, and aesthetic
Community Resilience
Strategic
THREATS TO BIODIVERSITY
1. Habitat Loss and Fragmentation:
A habitat is the place where a plant or animal naturally lives. Habitat loss is identified as main threat to 85% of all
species described as threatened or endangered. Factors responsible for this are deforestation, fire and over-use and
urbanization.
2. Over-exploitation for Commercialization:
Over-exploitation of resources has coasted more environmental degradation than earning. For example; shrimp farming
in India, Thailand, Ecuador and Indonesia results in Wetland destruction, pollution of coastal waters and degradation of
coastal fisheries. Scientific studies have concluded that cost of environmental degradation resulting from shrimp
farming was costing more than the earning through shrimp exports.
3. Invasive Species:
Invasive species are ‘alien’ or ‘exotic’ species which are introduced accidentally or intentionally by human. These
species become established in their new environment and spread unchecked, threatening the local biodiversity. These
invasive alien species have been identified as the second greatest threat to biodiversity after habitat loss. Today there
are 157 invasive plants in India.
4. Pollution:
Pollution is a major threat to biodiversity, and one of the most difficult problems to overcome; Pollutants do not
recognize international boundaries. For example, agricultural run-off, which contains a variety of fertilizers and
pesticides, may seep into ground water and rivers before ending up in the ocean. Atmospheric pollutants drift with
prevailing air currents and are deposited far from their original source.
5. Global Climate Change:
Many climatologists believe that the greenhouse effect is likely to raise world temperatures by
about 2°C by 2030, meaning that sea levels will rise by around 30-50 cm by this time. Global
warming, coupled with human population growth and accelerating rates of resource use will
bring further losses in biological diversity. Vast areas of the world will be inundated causing loss
of human life as well as ecosystems.
6. Population Growth and Over-consumption:
From a population of one billion at the beginning of the 19th century, our species now numbers
more than six billion people. Such rapid population growth has meant a rapid growth in the
exploitation of natural resources— water, foods and minerals. Although there is evidence that
our population growth rate is beginning to slow down, it is clear that the exploitation of natural
resources is currently not sustainable. Added to this is the fact that 25 per cent of the population
consumes about 75 per cent of the world’s natural resources. This problem of over-consumption
is one part of the broader issue of unsustainable use.
7. Illegal Wildlife Trade:
The international trade in wild plants and animals is enormous. Live animals are
taken for the pet trade, or their parts exported for medicines or food. Plants are
also taken from the wild for their horticultural or medicinal value.
8. Species extinction:
Extinction is a natural process. The geological record indicates that many hundreds
of thousands of plant and animal species have disappeared over the eras as they
have failed to adapt to changing conditions. Recent findings however indicate that
the current rate of species extinction is at least a hundred to a thousand times
higher than the natural rate.
SUMMARY
QUESTIONS
1. Define: Ecology and ecosystem.
2. Classify ecosystems.
3. What are the classifications of biotic components of ecosystems?
4. What is food chain and food web?
5. What are tropical levels?
6. What is energy flow?
7. Define the term producers and consumers.
8. Most fertile and productive soils in the world have developed under grassland. Why?
9. Name the factors that affect the aquatic ecosystem.
10. Explain why some of the ecological pyramids are upright while the others are
inverted in different ecosystems.
11.Why poaching of wild life is happening?
12. List the major threats to biodiversity.
13. Name the few endangered wild life species of India (AU)
Long Questions
1. Explain ecological pyramids.
2. Explain: (1) Forest ecosystem (2) Ecological succession
3. What are the different types of Eco-system and explain them with an example?
4. Briefly discuss the structural and functional components of an ecosystem.
5. Explain the functioning of hydrological cycle.
6. Discuss the environmental factors affecting the performance of an aquatic ecosystem.
7. Explain: The grass land ecosystem.
8. Write a note on food chain.
9. Write the short notes on the following: (i) Energy flow in ecosystem (ii) Pond ecosystem (iii) Threats to bio-diversity.
10. Explain the flow of energy in the atmosphere and its utilities in an ecosystem.
11. Explain the different components of an ecosystem with the help of pond ecosystem.
12. Explain the biodiversity of India.
13. Discuss the status of India as a mega diverse nation of biodiversity.
14. “Extinction is part of the evolutionary process. Then why should we bother about extinction of species”. Comment.
15. Briefly explain the conservation of bio-diversity.
16. Enumerate the major causes of degeneration of biodiversity.
17. With a neat sketch explain the flow of energy through the various components of the ecosystem (Producers, Consumers and
Decomposers)
18. Discuss the concept of ecological pyramids.
19. Explain the various types of values of biodiversity.
20. List the major endemic species of India. What are measures taken to conserve them?
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