1. Environmental Studies
Subject Code: 110007 (GTU)

2. Ecology and Ecosystem
Unit-2.1
Sub: Environmental Science

3. Introduction to Ecology
• The word ecology is derived from
Greek words ‘Oikos’ meaning
house, habitat or place of living
and ‘Logos’ meaning to study.
• Ecology is defined as the study of
interrelationship of different
organisms with each other and
with their environment. It is
concerned with the general
principles that apply to both
animals and plants.
• Under ecology, we study
various ecosystems which are
a part of the biosphere.
• An ecosystem includes all the
organisms and the nonliving
environment that are found in
a particular place.

4. Classification of Ecology
• Based on study area :
1. Autecology : It deals with the study of an individual species of
organisms and it’s population. The ecologists study the
behavior and adaptations of particular species to the
environmental condition at every stage of that individual’s life
cycle. It is also called the Species ecology. E.g. a fish in pond, a
tree in forest.
2. Synecology : It deals with the study of communities, their
composition, their behavior and relation with the environment.
It is also called as Ecology of communities. It is further divided
into 3 types : 1) Population Ecology
2) Community Ecology
3) Ecosystem Ecology
E.g. a pond, a forest.

5. 2. Based on Environment or habitat
1) Aquatic ecology : The study of interaction of organisms in the water
1) Marine water ecology
i) Ocean
ii) Deep Sea
iii) Estuary
2) Freshwater Ecology
i) Letic (Running water)
a) River
b) Stream
c) Spring
ii) Lentic (Standing Water)
a) Pond
b) Lake
Classification of Ecology
Fresh water river Coral reefs

6. 2) Terrestrial Ecology : The study of interaction of organisms on land :
a. Grassland Ecology
b. Forest Ecology
c. Desert Ecology
3. Based on Advancement in
the field of ecology
a. Productive ecology
b. Population ecology
c. Community ecology
d. Ecosystem ecology
e. Microbial ecology
f. Radiation ecology
g. Pollution ecology
h. Space ecology
Classification of Ecology
Forest
Ecology

7. Objectives of Ecological Studies
• It is important for humanity to understand its
environment because we have the ability to modify the
environment through the use of technology, and through
overexploitation of natural resources as a result of greed
or sheer pressure of numbers. Therefore, ecology is
more than just the understanding of the
interrelationships between organisms and their
environment; it also has social, political, economic and
technological dimensions.
• It also is a study of evolutionary development of
organisms, the biological productivity and energy flow in
the natural system.
• To develop mathematical models to relate interaction of
parameters and to predict the effects

8. • The term ecosystem was first coined by
A.G.Tansely.
• Ecosystem consists of two Words :
Ecosystem
Eco Environment
System Interaction

9. • According to E.P.Odum, an American ecologist, the
ecosystem is the basic functional unit of organism and
their environment interacting with each other and
with their own components.
• e.g. Grassland, Forest, Aquarium, Pond, Lake, River and
Ocean.
Grassland Ecosystem Forest Ecosystem Ocean Ecosystem

10. Types of Ecosystem
1. Natural Ecosystems : These
operate under natural
conditions without any major
interference by man.
i. Terrestrial Ecosystem :
Forest, grassland, desert,
etc.
ii. Aquatic Ecosystem :
a. Fresh water : Lotic
(running water like
spring, stream, or
rivers) or Lentic
(standing water as
lake, pond, pools, etc.)
b. Marine water : Such as
deep bodies as ocean
or shallow ones as Sea
or an estuary.
Lentic (standing water) lake
ecosystem
Lotic (flowing water) river ecosystem

11. Types of Ecosystem
2. Artificial (Man
Engineered)
Ecosystems : These
are maintained
artificially by man
where by addition of
energy and planned
manipulation,
natural balance is
disturbed regularly
e.g., crop land
ecosystem.
Crop land
ecosystem

12. Components of Ecosystem

13. Components of Ecosystem
1. Abiotic
• Consists of Non-living chemical & physical components such as water, air,
nutrients in the soil or water & Solar Energy.
• Physical & chemical factors that influence living organisms in land
(terrestrial) ecosystem & aquatic life zones.
• Abiotic factors can act as LIMITING FACTORS that keep a population at a
certain level.
Abiotic Components are mainly of two types:
1) Climatic Factors:
which include rain, temperature, light, wind, etc.
2) Edaphic Factors:
which include soil, pH, Topography, Minerals, etc.

14. 2. Biotic factors
• All the living things that directly or indirectly affect the ecosystem
biotic factors interact with other living organisms and the physical
environment can also be Limiting Factors ex. disease (bacteria),
predators, food resources.
• Made up of biological components consisting of living and dead plants,
animals and microorganisms.
• The Major Biological Components of Ecosystem :
a. Producers (Autotrophs)(self-feeders)
– Make their own food from compounds that are obtained from their
environment.
– Are the source of all food in an ecosystem.
– On land most producers are green plants.
– In freshwater and marine ecosystems, algae and plants are the major
producers near shorelines.
– In open water, the dominant producers are phytoplankton (most of them
microscopic) that float or drift in the water.
– Most producers capture sunlight to make carbohydrates (such as glucose)
by photosynthesis .
Components of Ecosystem

15. b. Consumers (Heterotrophs) (“other feeders”)
Get their energy and nutrients by feeding on other organisms
or their remains.
i. Primary consumers : Are those that eat producers
(plants) as a source of food. They are also known as
herbivores.
ii. Secondary consumers or carnivores : Eat other
animals.
iii. Tertiary Consumers : Large Carnivores which feed on
secondary consumers.
iv. Quaternary Consumers : Largest Carnivores that feed on
tertiary consumers. They are not eaten by any animals.
v. Omnivores : Have mixed diet that include both plants and
animals.
Components of Ecosystem

16. Components of Ecosystem
3. Decomposer :
• Mostly certain types of
bacteria and fungi are
specialized consumers
that recycle organic
matter in ecosystems.
• They do this by breaking
down (biodegrading)
dead organic material to
get nutrients and
releasing the resulting
simpler inorganic
compounds into the soil
and water, where they
can be taken up as
nutrients by producers.

17. The components of the ecosystem
are seen to function as a unit when
we consider the following aspects:
• Productivity
• Decomposition
• Energy flow
• Nutrient cycling

18. • Productivity - The rate of biomass production is
called productivity.
Units: g–2 yr –1 or (kcal m–2) yr–1
• Gross primary productivity - The rate of production
of organic matter during photosynthesis is called
gross primary productivity.
Gross PP (GPP) = total energy fixed
Net PP (NPP) = GPP – respiration
• Secondary productivity – The rate of formation of
new organic matter by consumers is called
secondary productivity .
PRODUCTIVITY

19. • The breakdown of complex organic matter
into inorganic substances like carbon
dioxide, water and nutrients and the process
is called decomposition.
Steps in decomposition
Fragmentation
Leaching
Catabolism
Humification
Mineralization

20. Decomposition cycle in a Terrestrial Ecosystem

21. Structure and function of an ecosystem

22.  Producers
(autotrophs)
 Consudmers
(heterotrophs)
 Decomposers

23. • Biological activities requires energy which ultimately comes from the sun.
Solar energy is transformed into chemical energy by a process of
photosynthesis this energy is stored in plant tissue and then transformed into
heat energy during metabolic activities.
• •Thus in biological world the energy flows from the sun to plants and then to
all heterotrophic organisms The flow of energy is unidirectional and non-
cyclic. This one way flow of energy is governed by laws of thermodynamics
which states that:
• •(a) Energy can neither be created nor be destroyed but may be transformed
from one form to another.
• •(b) During the energy transfer there is degradation of energy from a
concentrated form (mechanical, chemical, or electrical etc.) to a dispersed
form (heat).
• •No energy transformation is 100 % efficient, it is always accompanied by
some dispersion or loss of energy in the form heat. Therefore, biological
systems including ecosystems, must be supplied with energy on a continuous
Basis.

24. Summary energy flow in the
ecosystem
• All organisms require energy, for growth,
maintenance, reproduction, locomotion, etc.
• Hence, for all organisms there must be:
A source of energy
A loss of usable energy

26. Energy flow in an Ecosystem

27. Block diagram of an ecosystem

28. Energy Flow In Ecosystem
10% Law – Energy Loss
• During every transfer of energy in an ecosystem,
energy is lost as heat.
• Although heat can be used to do work (as in a steam
engine), it is generally not a useful source of energy
in biological systems.
• Thus, the amount of useful energy decreases as
energy passes through the levels of an ecosystem.
• This loss of energy limits the number of trophic levels
an ecosystem can support.
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29. Energy Flow In Ecosystem
10% Law – Energy Loss
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30. Energy Flow In Ecosystem
10% Law – Energy Loss
• When a plant harvests energy from sunlight,
photosynthesis captures only about 10% of the
energy available to the leaves.
• When a herbivore consumes a plant only about
10% of the energy in the plant ends up in the
herbivores molecules.
• When a carnivore consumes the herbivore, again
only 10% of the energy of the herbivore gets
passed along.
• As such 90% energy is lost into environment.8 Oct '14 30Ecology & Ecosystem

31. Energy Flow In Ecosystem
Models
• The flow of energy through various trophic levels in
an ecosystem can be explained with the help of
various energy flow models –
– Single channel energy flow model
– Y shaped or double channel energy flow model
– Universal energy model
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32. Energy Flow In Ecosystem
Models – Single channel
• The flow of energy takes place in a unidirectional
manner through a single channel of producers to
herbivores to carnivores.
• The energy once travelled by a lower trophic level to
higher one, cannot travel back to the lower level.
• Hence entire system would collapse if a lower trophic
level organism were cutoff.
• At each level there is progressive decrease in energy
due to loss as heat.
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33. Single Channel Energy Flow Model

34. Y- Shaped or Double Channel Energy Flow Model
• Y- shaped model shows a common boundary, light and heat flow
as well as import , export and storage of organic matter .
Decomposers are placed in separate box to partially separate the
grazing and detritus food chains. In terms of energy levels
decomposers are in fact a mixed group.
• •Y- shaped energy flow is more realistic and practical than the
single channel energy flow model because:
• •It conforms to the basic stratified structure of ecosystems
• •It separates the two chains i.e. grazing & detritus food chain in
both time and space. •Micro consumers (bacteria & fungi) and the
macro consumers (animals) differ greatly in size- metabolism
relations in two models.

35. Energy Flow In Ecosystem
Models – Double channel
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36. Energy Flow In Ecosystem
Models – Universal
• Energy is lost while moving from one trophic level to
another, indicated by narrower pipes and smaller
boxes.
• Energy lost is the one which is not utilized (NU). This
is lost due to locomotion, excretion, respiration (CR) ,
etc.
• Rest energy is used for production (P).
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37. Energy Flow In Ecosystem
Models – Universal
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38. Food Chain
• Every organism needs to obtain energy in order to live. For example, plants
get energy from the sun, some animals eat plants, and some animals eat
other animals.
• A food chain is the sequence of who eats whom in a biological community
(an ecosystem) to obtain nutrition

39. Food Chain
 A food chain shows the feeding relationship between
different living things in a particular habitat.
 Food chains show how energy is passed from the sun
to producers, from producers to consumers, and from
consumers to decomposers.
 In any ecosystem, many food chains overlap. When
this happens, the food chain forms a food web.

40. PRODUCERS
GRASS
GRASS
PRIMARY
CONSUMERS
SECONDARY
CONSUMERS
CARNIVORES
DEER
HERBIVORES
LION

41. Food Chain
Examples
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42. Food Chain
Examples
• In the above picture three food chains were
included.
– Grassland
• Producer – Grass
• Primary Consumer – Grasshopper
• Secondary Consumer – Rat
• Tertiary Consumer – Snake
– Pond
• Producer – Algea
• Primary Consumer – Mosquito
• Secondary Consumer – Dragonfly
• Tertiary Consumer – Frog
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43. Food Chain
Examples
– Ocean
• Producer – Phytoplankton
• Primary Consumer – Zooplanktons
• Secondary Consumer – Small Fish
• Tertiary Consumer – Tuna Fish
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44. The trophic level is the position of an organism it occupies in
the community or a food chain.
Ecologists study how energy moves through an
ecosystem by assigning organisms in that
ecosystem to a specific level called a trophic
level.

45. Energy flow in different Trophic Levels

46. Trophic Level: The trophic level of an organism is the position the
organism is in a food chain
Trophic levels are based on the ways organisms get food. Here these are:
Producer - plants or algae that use Carbon Dioxide and Water and Sunlight to
make their own food using photosynthesis
Consumer - animals who cannot make their own food and need to consume other
organisms for energy.
Three types:
o Herbivores: Animals that eat primary producers (like plants)
o Carnivores: Animals that eat other animals
o Omnivores: Animals that eat both plant and other animals
Decomposer – organisms that get energy by breaking down dead plant and animal
material and wastes. The decayed matter is then released as energy and nutrients
into the ecosystem for recycling.
Trophic Levels – 10% of energy is passed on, 90% lost as heat etc.
1: Primary producers - Plants and algae
2: Primary consumers - Herbivores
3: Secondary consumers – Carnivores that eat herbivores
4: Tertiary consumers - Carnivores which eat other carnivores
5: Top predators - have no predators and are at the top of the food chain.
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47. Energy Flow In Ecosystem
Trophic Level – Producers
• Producers - The lowest trophic level of an
ecosystem is occupied by the producers (plants,
algae, bacteria) which take sunlight and convert
it to food energy.
• It use the energy of the sun to build energy rich
carbohydrates.
• Ultimately all organisms get their energy from
the sun.
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48. Energy Flow In Ecosystem
Trophic Level – Consumers – Herbivorous
• A herbivore is an animal anatomically and
physiologically adapted to eating plant material.
• As a result of their plant diet, herbivorous animals
typically have mouthparts adapted to rasping or
grinding.
• Eg: Elephant, deer, grasshopper, etc.
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49. Energy Flow In Ecosystem
Trophic Level – Consumers – Carnivorous
• A carnivore meaning 'meat eater' is an organism that
derives its energy and nutrient requirements from a
diet consisting mainly or exclusively of animal tissue,
whether through predation or scavenging.
• Eg: Lion, panther, eagle, owl, etc.
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50. Energy Flow In Ecosystem
Trophic Level – Consumers – Omnivorous
• An omnivore is an animal that can derive its energy
and nutrients from a diet consisting of a variety of
food sources that may include plants, animals, algae,
fungi and bacteria.
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51. Energy Flow In Ecosystem
Trophic Level – Decomposers
• They assists in breaking down dead organisms and
helping return their nutrients to the Earth. E.g.:
worms, bacteria, fungi, etc
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52. Types of Food Chains
• Grazing Food Chain: This type of food chain starts from living
green plants goes to grazing herbivores and onto carnivores.
Ecosystem with such type of food chain directly depends
upon the solar energy for their food requirements.
• Most of the ecosystem in nature follow this type of food
chain.
In the first step plants convert the sun’s energy to chemical energy through
a process called photosynthesis. The chemical energy is stored both as
food and as structural elements in the plant.
The next step involves the primary consumers, animals that eat only
plants.
At step three are the secondary consumers, also called predators; these
animals eat primary consumers.
At step four are the tertiary consumers that eat secondary consumers, and
sometimes primary consumers as well.

53. Grazing Food Chain

54. Detritus food chain
The "detritus" food chain cycles energy from non-living remains of both
plants and animals (also called detritus).
The "detritus" food chain is a system where the energy produced by the
breakdown of dead plant and animal matter is cycled into the "grazing" food
chain.
Detritus is organic matter formed by decaying animal or plant tissue, or fecal
matter.
Detritus eaters (or detritivores) such as insects, worms and other small
organisms feed on dead plants, waste products from animals and dead
animals.
Decomposers are fungal or bacterial organisms that work within the dead
material to help break it down, activating decay and decomposition.
This important part of the ecosystem takes the last of the energy that was
originally absorbed by the plants and returns it to the soil.
5

55. Characteristics of Detritus Food Chain
a) Primary source of energy is dead organic matter called
'detritus' which are fallen leaves, plant parts or dead animal
bodies.
b) Primary consumers are 'detritivores' including protozoans,
bacteria, fungi, etc which feed upon the detritus saprophytically.
c) Detritivores are in turn eaten by secondary consumers such as
insect larvae, nematodes, etc.
d) Detritus food chains are generally shorter than grazing food
chains
e) In nature, detritus food chains are vital as the dead organic
matter of grazing food chain is acted upon by the detritivores to
recycle the inorganic elements into the ecosystem.

56. Detritus Food Chain

57. Food Web
 A food web is a graphical
description of feeding
relationship among
species in an ecological
community.
 It even specifies the
energy relation and
transfer of energy
amongst them.
 There are many food
chains contained in these
food webs

58. Food Web
• Food Web: The interconnected,
interlocking pattern of food chain is known
as food web.
• Under natural condition of the linear
arrangement of food chain hardly occurs
and they remain interconnected with each
other through different types of organisms
at different levels Such a interconnected
and interlocking pattern of food chain is
known as food web..

59. Food Web
• Multiple food chains connected together.
• The more chains the more stable the ecosystem.
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60. Food Web
Example
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62. Food Web
Example
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63. Food Web
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64. Biogeochemical Cycle
• The chemical interactions (cycles) that exist between
the atmosphere, hydrosphere, lithosphere, and
biosphere.
• Also known as Nutrient cycle.
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65. Biogeochemical Cycle
Various Forms
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66. Biogeochemical Cycle
Components
• All things in an ecosystem can either be biotic or
abiotic.
– Biotic : The living components of the ecosystem. E.g.:
Plants, animals, etc.
– Abiotic : the non-living components of the ecosystem. E.g.:
water, land, temperature, air, etc.
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67. Bio-Geo- Chemical Cycles
• •Nutrients, unlike energy are recycled in the ecosystem. The
Producers of an ecosystem take up several basic nutrients
from their non-living ecosystem. Materials are in limited
quantity in the earth’s system and to keep the system going
continuously, these materials get transformed into biomass of
the producers. Thus they are utilized by the consumer
population and are ultimately returned to the environment
with the help of reducers or decomposers. The unique
method evolved in nature is recycling materials continuously
is by linking them in cycle changes. This cyclic exchange of
nutrient material between the living organisms & their non-
living environment is called Bio-Geochemical cycle. As
indicated by the name the nutrients are circulated through life
(bio) and through earth(geo) repeatedly (cycle).

68. Elemental Cycles
H, O, and C make up > 99 % of the Earth’s biomass
N, Ca, K, Mg, S, and P are significant nutrients
Cycling of C, O, N, P, and S are discussed in this chapter

69. Hydrological cycle
At a glance
PrecipitationPrecipitation
Transpiration
Condensation
Evaporation
Ocean storage
Transpiration from
plants
Precipitation
to land
Groundwater movement (slow)
Evaporation
from land Evaporation
from ocean Precipitation
to ocean
Infiltration and
Percolation
Rain clouds
Runoff
Surface runoff
(rapid)
Surface
runoff
(rapid)
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70. Hydrological cycle
Major Steps
• Evaporation from the pool of water resource due to
heating by the sun.
• The process of evaporation from plants
is known as Transpiration (in other
words it is also known as plants
sweating).
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71. Hydrological cycle
Major Steps
• As water (in the form of gas) rises higher in the
atmosphere, it starts to cool and become a liquid
again. This process is called Condensation.
When a large amount of water vapor condenses,
it results in the formation of clouds.
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72. Hydrological cycle
Major Steps
• When the water in the clouds
gets too heavy, the water falls back to the earth. This
is called precipitation.
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73. Hydrological cycle
At a glance
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74. Hydrological Cycle
27

75. Hydrological Cycle
• •The natural flow of water through various components of environment resulting
in the global circulation is called water cycle. •Steps in Hydrological Cycle:
•Evaporation: Surface water is heated by sun and evaporates to become water
vapour, water vapour floats in the air.
• •Condensation: As water vapour rises into the air it gradually cools and
condenses and become minute droplet of water.
• •Clouds: Tiny droplets of water together forms clouds.
• •Precipitation: The fall of water on earth surface in any form of water it may be
in the form of dew, drizzle, rain is known as precipitation.
• •Runoff: Precipitated rain water accumulates and flows on the surface and sub-
surface towards rivers, streams, and underground stores and ultimately reaches
to sea.
• •Percolation & infiltration: The process of stored water flowing under earth,
merge to the ground water source is called percolation and infiltration
• •Transpiration: The water which directly evaporates from leaves of plants is
called Transpiration.
• •Completion of Cycle: All the water bodies continues its journey towards the
natural slope and meet the sea where the cycle starts again.

76. Hydrological cycle
1. Reservoir – oceans, air (as water vapor), groundwater,
lakes and glaciers; evaporation, wind and precipitation
(rain) move water from oceans to land.
2. Assimilation – plants absorb water from the ground,
animals drink water or eat other organisms which are
composed mostly of water.
3. Release – plants transpire, animals breathe and expel
liquid wastes.

77. Human Impact
Pollution of water
Reduces the vegetation cover increases the surface ran
off decreases the percolation
Global warming
Heavy deforestation reduces the transpiration loss of water
through plants and trees

78. Carbon Cycle
• The carbon cycle is the biogeochemical cycle by which carbon is
exchanged among the biosphere, pedosphere, geosphere, hydrosphere,
and atmosphere of the Earth.

79. Carbon Cycle
• The carbon cycle is the biogeochemical cycle by
which carbon is exchanged among the biosphere.
• It comprises a sequence of events that are key to
making the Earth capable of sustaining life; it
describes the movement of carbon as it is recycled
and reused throughout the biosphere.
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80. Carbon Cycle
At a glance
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81. Carbon Cycle
Major Steps
• Carbon moves from the atmosphere to plants – due
to photosynthesis it moves into plants body.
• Carbon moves from plants to animals – plants are
eaten by animals and they are in turn eaten by other
animals, and hence carbon moves along.
• Carbon moves from plants and animals to the ground
– their body decay when they die, and carbon is
pulled into the ground.
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82. Carbon Cycle
Major Steps
• Carbon moves to atmosphere – 3 ways –
– While respiration carbon is put back into air as CO2
– While burning of fossil fuel carbon is released as CO2
– The ocean and other water bodies absorb carbon from the
atmosphere.
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83. Carbon Cycle
At a glance
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84. Carbon Cycle
• •Carbon dioxide gas is emitted from various natural and
anthropogenic sources such as , volcanic eruptions, burning
forests, decomposition of carbonates, factories & Automobile
exhausts, during respiration by humans and plants. The plants
consume carbon dioxide during the process of
photosynthesis.
• •The major reservoir for carbon dioxide are in oceans, carbon
dioxide dissolves readily in water.
• •On land and in water, plants take up carbon dioxide and
convert it into carbohydrates during the process of
photosynthesis.
• •6CO2 + 6H20 C6 H12 O6 + 6 CO2
• •The plants are eaten by animals and when plants & animals
die the carbon content in the organic matter again return to
the soil with the help of decomposers.

85. Reservoirs of Carbon
Carbon is found in all four spheres
Biosphere - organic matter
Atmosphere - CO2, CH4
Hydrosphere - H2CO3 ,HCO3
- , CO3
=
Lithosphere - CaCO3 , coal, oil, and gas
Processes: photosynthesis, formation of sediments,
weathering, combustion, plate tectonics
Decay of organic material

86. Carbon Cycle
(carbon is required for building
organic compounds)
1. Reservoir – atmosphere (as CO2), fossil fuels (oil, coal),
durable organic materials (for example: cellulose).
2. Assimilation – plants use CO2 in photosynthesis; animals
consume plants.
3. Release – plants and animals release CO2 through respiration
and decomposition; CO2 is released as wood and
fossil fuels are burned.

87. Human Interference
Human-induced processes
Extraction and combustion of fossil fuels (speeds up the
medium-term cycling)
Cement manufacturing
Deforestation (biomass burning)
All of these processes release CO2 into the atmosphere and
affect the natural cycling of carbon

88. Nitrogen Cycle
• •Nitrogen is present in atmosphere as N2 in large amount (78
%) and it is fixed either by physical process of lightening or
biologically by some bacteria like rhizobium, aezotobacter and
cyanobacteria these microorganisms converts elemental
nitrogen into nitrates.
• Nitrogen in the for of Nitrates is taken up by plants and used
in metabolism for biosynthesis of amino acids, proteins,
vitamins etc. and passes through the food chain.
• After death of the plant and animals, the organic nitrogen in
dead tissues is decomposed by several groups of nitrifying
bacteria which convert them in to ammonia, nitrite & nitrates,
which are again used by plants.
• Some bacteria ( denitrifying bacteria) converts nitrates in to
molecular Nitrogen or N2 under anaerobic condition, which is
release back into atmosphere and the cycle goes on.

91. Nitrogen Cycle
(Nitrogen is required for the manufacture of
amino acids and nucleic acids)
1. Reservoir – atmosphere (as N2); soil (as NH4
+ or
ammonium, NH3 or ammonia, N02
- or nitrite, N03
-
or nitrate
2. Assimilation – plants absorb nitrogen as either NH4
+ or as
N03
-, animals obtain nitrogen by eating plants and
other animals. The stages in the assimilation of
nitrogen are as follows:
3. Release – Denitrifying bacteria convert N03
- back to N2
(denitrification); detrivorous bacteria convert
organic compounds back to NH4
+
(ammonification); animals excrete NH4
+ (or NH3)
urea, or uric acid.

92. 30

93. Human Impact
Harvesting of timber
Automobile and industrial exhaust
Acid rain is caused by emissions of sulfur
dioxide and nitrogen oxide, which react with
the water molecules in the atmosphere to produce acids.
NO2 + OH· → HNO3
Eutrophication

94. Oxygen Cycle
• • Atmosphere contains about 21 % of oxygen. Almost all living
organisms need oxygen. They use oxygen during the process of
creating energy or process of photosynthesis.
• •Just as water moves from sky to earth and back into
hydrological cycle, oxygen is also cycled through the
environment. Plants mark the beginning of oxygen cycle. Plant
produce oxygen during the process of photosynthesis. Animal
form the other half of the oxygen cycle, they breath oxygen. So
the oxygen created in plants are used up by animals.
• •There is continuous exchange of O2 between the atmosphere
and all water surface on the earth. The total amount of O2 in the
biosphere is relatively constant, so that the oxygen cycle may get
stable.

97. Oxygen cycle

98. Oxygen Cycle
Essential for aerobic life
Closely linked to carbon cycle
Very large reservoir (21% of gas in atm.), not susceptible to
human interference
Also, not a greenhouse gas
Reservoirs: atmosphere, surface organic material (biosphere),
and buried organic matter (lithosphere)

99. Oxygen Cycle
Processes
Photosynthesis/ respiration: short-term cycle; balanced on
land; excess O2 in ocean -phytoplanktons
Mineral oxidation, weathering, burial - removes O2 from
atmosphere
Combustion or weathering of organic matter - removes O2
from atmosphere
Atmosphere => marine biota => sediments => rocks =>
atmosphere (fig )

100. Oxygen
Cycle
31

101. Phosphorus Cycle
• •The Phosphorus cycle is the simplest of all cycles. Phosphorus is generally
available in the soluble form i.e. phosphate (PO4-3). Which is a phosphorous
atom with 4 oxygen atoms. This heavy molecules never makes into the
atmosphere, they are always present in dissolved form in water or in the rock.
When phosphorous rock dissolves in water the phosphate goes into the
solution. Producer take this phosphorous up and use it in various metabolic
activities. Phosphate is considered to be a important constituent of cell
membrane, DNA, ATP.
• •Consumer obtain their phosphorus from plants they eat.
• •Animals also use phosphorous as a component of bones & teeth, shells.
When animal or plant die, phosphate returns to the soil or water by the
decomposers.
• •Nowadays the synthetic detergents & fertilizers have also become a source of
Phosphates in a water course. Thus excess of phosphates due to these sources
have resulted in a problem of Eutrophication.(i.e. Excess of plant growth).

104. Phosphorus Cycle
1. Reservoir – erosion transfers
phosphorus to water and soil;
sediments and rocks that
accumulate on ocean floors return
to the surface as a result of uplifting
by geological processes
2. Assimilation – plants absorb
inorganic PO4
3- (phosphate) from
soils; animals obtain organic
phosphorus when they plants and
other animals
3. Release – plants and animals
release phosphorus when they
decompose; animals excrete
phosphorus in their waste products
33

105. Sulphur Cycle
• •Sulphur occurs both in free state as well as
sulphides and sulphates as PBs, ZnS, BaSO4, etc.
Sulphur is very essential element for the living
organisms for synthesizing amino acids, enzymes,
co-factors and certain vitamins. The burning of fossil
fuels and volcanoes releases H2S and SO2 gas in
atmosphere, which ultimately returns to the soil as
sulphuric acid along with rain, forming sulphate
compounds. Sulphur in the form of SO4-2 is
absorbed by plants. The elemental Sulphur
converted to sulphates SO4-2 is also released into
the soil through weathering of some sulphates
containing rocks.

108. ECOSYSTEM
• An ecosystem is a community of living
organisms called producers, consumers, and
decomposers
• The study of certain processes that link the
living, or biotic, components to the non-living,
or abiotic, components
• Ecosystem = Community + Abiotic
environment, interacting
27.02.2016 108S.M.B.T. College of Pharmacy, Nandi Hills

109. Classification of Ecosystem

111. Types Of Ecosystems
 Forest Ecosystem
 Grassland Ecosystem
 Desert Ecosystem
 Aquatic Ecosystem
 Estuarine Ecosystem

112. Forest Ecosystem
• •Forest Occupy roughly 40 % of the land. The different components of forest ecosystem
are as follows:
• •Abiotic Components: These are organic & inorganic substances present in the soil
and atmosphere. In addition to minerals present in forest we find the dead organic
debris, moreover light conditions are different due to complex stratification in the
plants.
• •Biotic Components:
• •Producers These are mainly trees that show much species and greater degree of
stratification. Besides trees there are also present shrubs, and ground vegetation.
• •Consumers:
• Primary Consumers: These are herbivores that include animals feeding on tree
leaves, ants, beetles, grass hoppers, etc., and large elephants, dears, squirrels, etc.
• •Secondary Consumers: These are carnivores, like snakes, birds, lizards, fox, etc.
feeding on herbivores.
• •Tertiary consumers: These are top carnivores like lion tiger, etc. that eat carnivores
of secondary level.
• •Decomposers: These are wide variety of micro organisms including, fungi, bacteria.

113. Functions Forest Ecosystems
 Enhance the water resources in both quality and quantity
 Hydrological cycle depend on the forest ecosystem
 Forest gives shelter to wildlife and fish
 Considered as a pathway for exchange and regulation of
atmospheric gases, water and trace elements

114. Forest Ecosystem
• They have a predominance of trees that are interspersed with large
number of species of herbs, shrubs, climbers, lichens algae & a
variety of wild animals & birds.
• Depending upon the climatic conditions forests can be of different
types :
1. Tropical Rain Forest
2. Tropical Deciduous forests
3. Tropical Scrub Forests
4. Temperate Rain Forests
5. Temperate Deciduous Forests
6. Evergreen Coniferous Forests

115. Coniferous forest of Alaska Tropical rain forest
Deciduous Forest
15

117. Grassland Ecosystem
• Grassland occupy comparatively fewer area roughly 19 % of the earth’s
surface.
• •Abiotic Components: These are nutrients present in soil, and aerial
environment, thus the elements like, phosphates, sulphates, water, carbon
dioxide, present in soil and in air. Moreover some trace elements are also
present.
• •Biotic Components:
• •Producers: They are mainly grasses as species of Cynadon, Desmodium,
besides them a few shrubs also contribute some primary production.
•Consumers:
• •Primary Consumers: The herbivores feeding on grasses are grazing animals,
as cows, goats, rabbit, etc. besides them there are some insects as termites,
millipedes that feed on grasses.
• •Secondary Consumers: These are carnivores feeding on herbivores these
include, animals like, fox, jackals, snakes, frogs, birds.
• •Tertiary Consumers: Some times hawks, vultures, feeding on secondary
consumer, thus occupy tertiary consumers.
• •Decomposers: The microbes active in the decay of dead organic matter of
different form are fungi and some bacteria

120. Desert Ecosystem
• •Desert occupy 17 % of land.
• •Abiotic components include, light, temperature, minerals.
•Biotic Components:
• •Producers : These are shrubs, especially bushes, some
grasses, and few trees. •E.g. Cacti, Xerophytes, mosses
•Consumers: The most common animals are reptiles, and
insects, there are some rodents, and birds, and above all ship
of desert camels, feed on tender plants.
• •Decomposers: These are very few as due to poor vegetation
the amount of dead organic matter is less. They are some
fungi and bacteria.

122. Types Of Desert Ecosystem
Hot and Dry Deserts
Cold Deserts
Semi-Arid Deserts
Coastal Deserts

123. Thar Desert
Sahara Desert
Mojave in south California
Gobi desert in China

125. Aquatic Ecosystem
 It is an ecosystem located in
a water bodies.
 The two main types of
aquatic ecosystems are
marine ecosystems and
freshwater ecosystems.

126. Types Of Aquatic Ecosystem
 Marine Ecosystem.
 Freshwater Ecosystem
1.Lentic
2.Lotic
3.Wetland

128. 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
• Aquatic Ecosystem can be further classified into :
1. Fresh water Ecosystem
- Pond Ecosystem : small bodies of freshwater with shallow and still
water, marsh, and aquatic plants
- Lake Ecosystem : slow moving water like pools, ponds, and lakes.
- River Ecosystem : large streams flowing downwards from the
mountain highlands into the sea
2. Marine Ecosystem : cover approximately 71% of the Earth's surface and
contain approximately 97% of the planet's water

129. Aquatic Ecosystem
• Detailed information about aquatic system

130. Types Of Aquatic Ecosystem
Freshwater Ecosystem
1. Pond ecosystem
2. Lake ecosystem
3. Stream
4. Riverine Ecosystem
5. Fresh water marshes ecosystem

131. Ocean Ecosystem
• •Ocean Ecosystem are more stable than pond ecosystem, they occupy 70 % of
the earth surface.
• •Abiotic Components: Dissolved oxygen, light, temperature, minerals.
•Biotic Components:
• •Producers: These are autotrophs and are also known Primary producers.
They are mainly, some microscopic algae (phyto-planlanktons) besides them
there are mainly, seaweeds, as brown and red algae also contribute to
primary production.
• •Consumers: They are all heterotrophic macro consumers
• •Primary Consumer: The herbivores, that feed on producers are shrimps,
Molluscs, fish, etc.
• •Secondary Consumers: These are carnivores fish as Herring, Shad, Mackerel,
feeding on herbivores.
• •Tertiary Consumers: These includes, other carnivores fishes like, COD,
Halibut, Sea Turtle, Sharks etc.
• •Decomposers: The microbes active in the decay of dead organic matter of
producers, and animals are chiefly, bacteria and some fungi.

133. Estuarine Ecosystem
• •An estuary is a partially enclosed body of water along the coast where fresh
water from river and streams meet and mix with salt water from oceans. This
Ecosystems are considered as most fertile ecosystem.
• •Abiotic Components: Nutrients such as phosphorus and nitrogen,
temperature, light, salinity, pH.
• •This ecosystem experience wide daily and seasonal fluctuations in
temperature and Salinity level because of variation in freshwater in flow.
• •Biotic Components:
• •Producers: Phyplanktons- these micro-organisms manufacture food by
photosynthesis and absorb nutrients such as phosphorous and nitrogen,
besides them, mangroves, sea grass, weeds, and salt marshes.
• •Consumers: Primary consumers, Zooplanktons that feed on Phytoplankton,
besides them some small microorganisms that feed on producers.
•Secondary Consumer: Include worms, shellfish, small fish, feeding on
Zooplanktons
• •Tertiary Consumer :Fishes, turtles, crabs, starfishes feeding on secondary
consumers.
• •Decomposers: Fungi & Bacteria are the chief microbes active in decay of
dead organic matter.

134. Estuaries
• An estuary is a semi closed coastal body of water that has free connection
with sea.
• An area in which fresh water from a river mixes with salt water from the
ocean; a transition area from the land to the ocean. Other names: bay,
sound, lagoon, harbor, or bayou
River bringing
freshwater to the
sea
The Ocean
Area where fresh
and salt water
mix

135. Characteristics of Estuaries
• Very nutrient rich ecosystems  leads to high
productivity and high biodiversity.
• There is a gradual increase in salinity as you go from
the river (0-5ppt) to the middle of the estuary (5-
25ppt), to the ocean (>25 ppt) .
ppt = parts per thousand
• Sediment settles out in the estuary when the water
slows down.
• Nutrients accumulates on the bottom (benthic zone).
• Pollutants are absorbed in estuaries.

136. Pond ecosystem

137. Pond Ecosystem
• •Producers are of following type •Macrophytes: these are large rooted plants,
which include partly or completely submerged hydrophytes, eg Hydrilla, Trapha,
Typha. •Phytoplankton: These are minute floating or submerged lower plants eg
algae.
• •Consumers: They are heterotrophs which depends for their nutrition on the
organic food manufactured by producers.
• •Primary Consumers: – Benthos: These are animals associated with living plants
,detrivores and some other microorganisms –Zooplanktons: These are chiefly
rotifers, protozoans, they feed on phytoplankton
• •Secondary Consumers: They are the Carnivores which feed on herbivores, these
are chiefly insect and fish, most insects & water beetles, they feed on
zooplanktons.
• •Tertiary Consumers: These are some large fish as game fish, turtles, which feed
on small fish and thus become tertiary consumers.
• •Decomposers: They are also known as micro-consumers. They decompose dead
organic matter of both producers and animal to simple form. Thus they play an
important role in the return of minerals again to the pond ecosystem, they are
chiefly bacteria, & fungi.

139. Riverine Ecosystem
• •As Compared with lentic freshwater (Ponds & lakes), lotic waters
such as streams, and river have been less studied. However, the
various components of an riverine and stream ecosystem can be
arranged as follows.
• •Producers: The chief producers that remain permanently attached
to a firm substrata are green algae as Cladophora, and aquatic
mosses.
• •Consumers: The consumers show certain features as permanent
attachment to firm substrata, presence of hooks & suckers, sticky
undersurface, streamline bodies, flattened bodies.. Thus a variety of
animal are found, which are fresh spongy and caddis-fly larvae,
snails, flat worms etc.
• •Decomposers: Various bacteria and fungi like actinomycetes are
present which acts as decomposers.

140. • An ecological pyramid is a graphical representation of trophic levels
in a given ecosystem.
Ecological
Pyramids
Pyramid of
Number
Pyramid of
Biomass
Pyramid of
Energy

141. An ECOLOGICAL PYRAMID is a graphical
representation designed to show…….
 the number of organisms,
 energy relationships, and
 biomass of an ecosystem.
They are also called Eltonian pyramids after
Charles Elton, who developed the concept of
ecological pyramids.
Charles Elton (1927) developed the concept of
ecological pyramids who noted that "…the
animals at the base of a food chain are
relatively abundant while those at the end are
relatively few in number…"

142. Producer organisms (usually green plants) form the base of
the pyramid, With succeeding levels above representing the
different trophic levels (respective position of the organisms
within ecological food chains).
Succeeding levels in the pyramid represent the dependence
of the organisms at a given level on the organisms at lower
level.

143. There are three types of pyramids:
of numbers, of biomass, and of
energy.
9

144. Energy Pyramids
Types - Number
• Illustrates of the number of organisms at each level.
8 Oct '14 144Ecology & Ecosystem

145. Pyramid Of Numbers:
• A pyramid of numbers is a graphical
representation of the numbers of
individuals in each population in a
food chain. Often it is drawn from the
autotrophic level up. A pyramid of
numbers can be used to examine how
the population of a certain species
affects another. Often, the
autotrophic level in a pyramid of
numbers is much larger than any of
the higher trophic levels, and the
numbers decreases upon ascending
the pyramid. There are exceptions,
however. For example, in a tree
community, a single tree could
support many different populations of
larger numbers.

146. Pyramid of Numbers
 The pyramid of numbers represents the number of organisms in each
trophic level. This pyramid consists of a plot of relationships between the
number herbivores (primary consumers), first level carnivore (secondary
consumers), second level carnivore (tertiary consumers) and so forth. This
shape varies from ecosystem to ecosystem because the number of
organisms at each level is variable
 Upright, partly upright and inverted are the three types of pyramids of
numbers.
 An aquatic ecosystem is an example of upright pyramid where the number
of organisms becomes fewer and fewer higher up in the pyramid.
 A forest ecosystem is an example of a partially upright pyramid, as fewer
producers support more primary consumers, but there are less secondary
and tertiary consumers.
 An inverted pyramid of numbers is one where the number of organisms
depending on the lower levels grows closer toward the apex. A parasitic
food chain is an example.

147. 11

148. 12

149. Pyramid of Number
• •They show the relationship between producers, herbivores, and
carnivores at successive tropic levels in terms of their number
• . •In case of grassland ecosystem the producers are mainly
grasses and are always maximum in number this number then
shows a decrease towards apex as primary consumers like mice,
rabbit are lesser in number than grasses, the secondary
consumers like lizard, snake, are even lesser in number than the
grasses, finally the top tertiary consumers like hawks are least in
number. Thus the shape of pyramid is upright.
• But in case of forest ecosystem the pyramids is always inverted
because the producers are mainly large trees, are lesser in
numbers, the herbivores fruit eating birds are more in number
than the producers, then there is gradual decrease in number of
secondary consumers thus making pyramid upright again. Thus
the pyramid of number does not give a true picture of the food
chain and are not very functional.

151. Energy Pyramids
Types - Biomass
Illustrates the amount of biomass in each trophic
level. Biomass weight is determined after
dehydration
Shows the amount
of matter lost
between trophic
levels. Measured
in Kg, grams or
pounds.
8 Oct '14 151Ecology & Ecosystem

152. Energy Pyramids
Types - Biomass
• One problem: They can make a trophic level look like
it has more energy than it really does.
• For example: A bird has a beak, feathers and a
skeleton that would count as biomass even though it
does not contribute to the overall flow of energy into
the next trophic level.
8 Oct '14 152Ecology & Ecosystem

153. • The pyramid of biomass in sea is also
generally inverted because the biomass of
fishes far exceeds that of phytoplankton.
PYRAMID OF BIOMASS

154. Pyramid of Biomass
 Biomass is (is the mass of living biological organisms in
a given area or ecosystem at a given time) renewable
organic (living) material.
 A pyramid of biomass is a representation of the amount
of energy contained in biomass, at different trophic
levels for a particular time.
 It is measured in grams per meter2, or calories per
meter2. This demonstrates the amount of matter lost
between trophic levels.
 Each level is dependent on its lower level for energy,
hence the lower level determines how much energy will
be available to the upper level. Also, energy is lost in
transfer so the amount of energy is less higher up the
pyramid.

155.  There are two types of biomass pyramids: upright and
inverted.
 An upright pyramid is one where the combined weight of
producers is larger than the combined weight of
consumers. An example is a forest ecosystem.
 An inverted pyramid is one where the combined weight of
producers is smaller than the combined weight of
consumers. An example is an aquatic ecosystem.

156. Pyramid of Biomass
• •The pyramid of biomass represents the relationship
between different tropic levels in terms of biomass.
• •There is generally gradual decrease in biomass of
organisms at successive levels from the producers to
the top carnivores. Thus pyramid of biomass is upright
for grassland ecosystem.
• •However in case of a pond as the producers are
algae, are least in number and this value gradually
shows an increase towards the apex of pyramid thus
making the pyramid inverted in shape.

159. Energy Pyramids
Types - Energy
• Shows the energy available at each trophic level.
– The size of the blocks represents the proportion of
productivity
– Measured in Joules or Calories
8 Oct '14 159Ecology & Ecosystem

160. • Most of the energy available to the community is in
the 1st trophic level.
• Only 10-20% of the energy is available to the next
trophic level (≈ 90% lost)
Energy Pyramids
Types - Energy
8 Oct '14 160Ecology & Ecosystem

162. • Pyramid of energy is always upright.
• It can never be inverted.
PYRAMID OF ENERGY

163. • Start with 1,300,000,000 cal. at the Diatom (Producer)Level
• Properly complete both Niche and Energy data.
Energy
Pyramids
compare
the energy
available
at each
trophic
level of a
food chain
in an
ecosystem.
1,300,000,000
130,000,000
13,000,000
1,300,000
130,000
13,000
1,170,000,000
117,000,000
11,700,000
1,170,000
117,000
Producer
Omnivore
1st level Consumer
Omnivore
2nd level Consumer
Carnivore
3rd level Consumer
Carnivore
4th level Consumer
Top Carnivore
5th level Consumer
jschmied©2016

164. Pyramid of Energy
• Of the 3 types of ecological pyramid the energy
pyramid gives the best picture of overall nature of
the ecosystem. In this type of pyramid the tropic
level is decided depending upon the rate at which
food is being produced.
• •In shape it is always upright as in most of the
cases there is always gradual decrease in the
energy content at successive trophic level from
producers to various consumers.