The document discusses ecology, defined as the study of organisms interacting with their environment in ecosystems, which consist of abiotic (non-living) and biotic (living) components. It covers energy flow, food chains, and the roles of producers, consumers, and decomposers in ecosystems, as well as ecological pyramids and natural versus artificial ecosystems. Additionally, it outlines ecological succession, distinguishing between primary and secondary succession processes.

1. Dr. M.Saraswathi,

2. ECOLOGY:
 Everything in the natural world is connected.
 Ecology: It deals with the study of organisms in their
natural home interacting with their surroundings.

3. ECOSYSTEM
• The self-sustaining structural and functional interaction
between living and non-living components.
• Ecosystem is the basic functional unit of ecology.
• Ecosystem is derived from Greek, means “Study of
home”.
• Ecosystem has been defined as a system of organisms
with surroundings.

4. An ecosystem consists of two main components
Abiotic or Non-living components.
1. Climatic Factors
2. Physical Factors
3. Chemical factors
Biotic or Living components.
1. Autotrophs or Producers
2. Heterotrophs or Consumers
3. Saprotrophs or Decomposers

5. ABIOTIC FACTORS:
1. Climatic Factors: Temperatures,
Moisture, Wind etc.,
2. Physical Factors: light, Fire,
pressure etc.,
3. Chemical Factors: inorganic substances (minerals),
pH,
Salinity and organic substances etc.,

6. BIOTIC COMPONENTS
Autotrophs
 Autotrophs (=self-nourishing) are called as
producers.
 Photosynthesis—use light energy to convert
carbon dioxide and water into oxygen and
carbohydrates (= green plants, algae, some
bacteria)
 6CO2 + 6H2O 6O2 + C6H12O6
Autotrophs
simple
inorganic
compounds
complex
organic
compounds
light

7. Photosynthesis
Chemosynthesis
 chemosynthesis is the biological conversion of one or more
carbon molecules and nutrients into organic matter using the
oxidation of inorganic molecules or methane as a source of
energy, rather than sunlight, as in photosynthesis.
chemoautotroph
Reduced
inorganic
compounds
complex
organic
compounds
oxygen

8.  CONSUMERS may also be classified as follows depending
upon their food habits:
 i. Primary consumers(Herbivores)
 ii. Secondary consumers(Primary carnivores)
 iii. Tertiary consumers(Secondary carnivores)
Herbivores: Animals that feed on plants. Ex. Cattle, elephant
—obtain energy
by eating only plants

9.  Primary Carnivores: Animals that feed on the
Herbivores.
—eat only animals

10. Secondary Carnivores: Animals that feed on the
Herbivores and primary carnivores.
—eat only animals

11. Omnivores—eat both plants and animals
Decomposers—breaks down dead organic matter

12. The function of an ecosystem is to allow flow of energy and cycling of
nutrients
1. Primary Function: Manufacture of starch by photosynthesis with
the help of minerals take from their edaphic environment.
2. Secondary Function: Distribution of energy in the form of food
for all consumers.
3. Tertiary Function: When plants and animals die, then
decomposers(like certain bacteria and fungi) act on their dead
bodies and decompose them into simple materials like carbon
dioxide, water and minerals which go back to air, water bodies
and soil from where they were taken.

14. Energy flow in an ecosystem:
 Energy is the most essential requirement for all living
organisms.
 Solar energy is the main source of earth planet. Solar energy is
transformed to chemical energy in photosynthesis by green
plants.
 Some amount of chemical energy is used by plants for their
growth, remaining is utilized for all living organisms.
 This is the first and most essential step to provide energy for all
living organisms in an ecosystem. Thus, the energy enters in
the ecosystem through photosynthesis and passes different
feeding levels.

15. Energy flow - Thermodynamics:
The flow of energy through an ecosystem follows two laws
of thermodynamics.

16. ENERGY FLOW- LAWS OF
THERMODYNAMICS
FIRST LAW of THERMODYNAMICS:
 Energy can be converted from one form to
another, but cannot be created or destroyed.
 Energy for an ecosystem comes from sun. It is absorbed by plants.
Where it is converted into stored chemical energy, i.e. solar energy is
converted into chemical energy.

17. SECOND LAW of THERMODYNAMICS
 It states that “whenever energy is transformed, that is a loss of
energy through the release of heat”.
 In energy exchanges in a closed system, the potential energy of
the final state will be less than that of the initial state
Examples
 Internal combustion engines in cars are 25% efficient in
converting chemical energy to kinetic energy; the rest is not used
or is lost as heat.
 There will be a loss of energy in the form of heat as it moves
from one tropic level to another tropic level. The loss of energy
takes through respiration, running, hunting e etc.

18. ENERGY FLOW
 This pattern of energy flow among different organisms
is the TROPHIC STRUCTURE of an ecosystem.
heat
Producers Consumers
Decomposers
heat

19. Trophic Levels—each step in a food chain or food web
1. Level 1—Producers (autotrophs)
2. Level 2—Primary Consumers (herbivores)
3. Level 3—Secondary Consumers
(carnivores or omnivores)
4. Level 4—Tertiary Consumers
(carnivore—usually top carnivore)
5. Level 5 — Decomposers

20. Food Chain—“The sequence of eating and being eaten in an ecosystem is
known as food chain”
Or
“Transfer of food energy the through a series of organisms in different tropic levels
is referred to as food chain”. Start with producer and end with top consumer or
carnivores
Ex: grass grasshopper frog raccoon

22. Types of food chain:
1.Grazing food chain: The food chain starts from plants
goes through herbivores and ends with carnivores. This
food chain depends on the autotrophs, which can capture
the energy from solar radiation.
2.Detritus food chain: Detritus food chain starts from
dead organic matters and ends with inorganic compounds.
In this type of food chain, microorganisms are feed their
food from animal and plants dead bodies. Microorganisms
are also called as detritivores.

23. In a forest ecosystem:
Grazing food chain
Detritus food chain

24. In a Grassland ecosystem:
Grazing food chain
Detritus food chain
The above two food chains can not operate independently. They are
interconnected at various levels. The grazing food chain gets energy
from plants, while the detritus food chain gets energy from dead
plants.

25. Food Web: The interlocking pattern of various food chains in an
ecosystem is known as food web.
A food web is a network of food chains where different types of living
organisms are connected at different tropic levels, so that there are a
number of options of eating and being eaten at each tropic level.
Hawks
Weasels Raccoons
Mice
Grass

26. Hawks
Weasels Raccoons
Mice
Grass
Food Webs

27. The number, biomass and energy of the organisms gradually
decrease from the producer level to the consumer level. This can be
represented in the form of a pyramid called ecological pyramid. In the
ecological pyramids, the producers form the base and the consumers
occupy the apex. There are three types of ecological pyramids namely
1.Pyramid of Biomass
2.Pyramid of energy
3.pyramid of numbers

28. PYRAMID OF BIOMASS:
• The amount of biomass in each trophic level
 In this particular type of ecological pyramid, each level
takes into account the amount of biomass produced by
each trophic level.
 The pyramid of biomass is also upright except for that
observed in oceans where large numbers of
zooplanktons depend on a relatively smaller number of
phytoplanktons.

29. PYRAMID OF BIOMASS

30. PYRAMID OF ENERGY:
• Shows the energy available at each trophic level.
 Pyramid of energy is the only type of ecological pyramid, which is
always upright as the energy flow in a food chain is always
unidirectional. Also, with every increasing trophic level, some
energy is lost into the environment.

31. PYRAMID OF NUMBERS:
In this type of ecological pyramid, the
number of organisms in each trophic level is
considered as a level in the pyramid.
The pyramid of numbers is usually upright
except for some situations like that of the
detritus food chain, where many organisms
feed on one dead plant or animal.

33. Natural ecosystem
1.Terrestrial ecosystem (grasslands, forests, desert
ecosystems)
2.Aquatic ecosystem
a. Lentic (Stagnant water) like lake, ponds etc.
b. Lotic (Flowing water) like river, ocean, sea, etc.
Artificial
1.A crop land, garden, aquarium, park, kitchen garden.

34. Forest Ecosystems

35. FORESTS
Deciduous forests Tropicalrain forests Coastalforests Coniferous forests
A forest is an area in which the main plants that grow there are trees.
A forest is a living community of various species of trees and
smaller forms of vegetation. Forest ecosystem covers about 40% of land
area of the earth.

36. CHARACTERISTICS OF FOREST
ECOSYSTEM
 Forests are characterized by warm temperature and
adequate rainfall, which makes the generation of no. of ponds
and lakes.
 The forest maintains climate and rainfall
 The forest supports many wild animals and protect
biodiversity
 Soil is rich in organic matter and nutrients, which supports
the growth of trees
 In the forest, the penetration of light is very poor; the
conversion of organic matter into nutrients is very fast.

38. GRASSLAND ECOSYSTEMS

39. GRASSLANDS
 Grasslands are
occupies 20% of the
earth surface. In
addition to grass
species, some trees and
shrubs also present in
the grassland. Limited
grazing improves the
grasslands and
overgrazing degrades
the lands resulting
desertification.

40. TYPES GRASSLANDS
Depending upon the
climate conditions,
grasslands can be
classified into three
types
1. Tropical grasslands
2. Temperate grasslands
3. Polar grasslands

41. CHARACTERISTICS OF GRASSLANDS
 Grassland ecosystem is a plain land occupied by grasses
 Soil is very rich in nutrients and organic matters.
 Since it has tall grass, it is ideal place for grazing
animals.
 It is characterized by low or uneven rainfall.

42. STRUCTURE & FUNCTION OF THE
GRASSLAND ECOSYSTEM

43. DESERT
ECOSYSTEMS

44. DESERTS
 Deserts occupy 35% of world’s land area. It is
characterized by less than 25cm rainfall. The
atmosphere is dry, so it is a poor insulator.
 Types of desert ecosystem:
Based on the climatic conditions, deserts are
classified into three types.
 Tropical deserts
 Temperate deserts
 Cold deserts

45. CHARACTERISTICS OF DESERT
ECOSYSTEM
 The desert air is dry and the climate is hot
 Vegetation is very less. Because the soil is
very poor in nutrients and organic matter

46. STRUCTURE AND FUNCTION OF
THE
DESERT ECOSYSTEM

47. Roadrunner
Anteater
Scorpion
Gila monster (lizard)
Camel

48. The aquatic ecosystem deals with water bodies. The
aquatic ecosystems have numerous small and large
species of plants and animals. Aquatic ecosystem can
be classified into two types
Fresh water bodies: Ponds, streams, lakes and
rivers
Marine water ecosystem: Oceans, estuaries

49. PONDS ECOSYSTEM
PONDS ECOSYSTEM

50. Ponds Ecosystem
Ponds Ecosystem
It is a small fresh water aquatic ecosystem,
where water is stagnant. It receives water
during rainy season.
Characteristics of ponds:
Pond is temporary, only seasonal
Ponds get polluted easily due to limited
amount of water

51. Components or structure & function of ponds
ecosystem

52. LAKES
LAKES
ECOSYSTEM
ECOSYSTEM

53. Lake Ecosystem
Lake Ecosystem
Lakes are formed by water from rainfall,
melting snow and streams.
Characteristics of Lake Ecosystem:
Lake is a shallow fresh water body
It is permanent water body with large water
resources
It helps in irrigation and drinking

54. STRUCTURE & FUNCTION OF THE
LAKE ECOSYSTEM

55. RIVER/ STREAM
ECOSYSTEMS

56. RIVER/STREAM ECOSYSTEM
The number of animals is low in river or stream.
Characteristics of river or stream:
 It is a fresh water, and free flowing water system
 Due to mixing of water, dissolved oxygen content is
more
 River deposits large amount of nutrients.

57. COMPONENTS OR STRUCTURE &
FUNCTION OF RIVER OR STREAM
ECOSYSTEM

58. Ocean Ecosystem

59. Oceans cover more than two third of the earth’s surface. The
ocean environment is characterized by its high concentration of
salts and minerals.

60. Characteristics of ocean ecosystem:
It occupies a large surface area with
saline water
It is rich in biodiversity
It moderates the temperature of the
earth
It is used for commercial like marine,
ship etc.
Ocean Ecosystem

61. Components or structure & function of an ocean
ecosystem

63. Phytoplankton Blooms
Bands of the dionflagellate
Lingulodinium polyedrum
moving onshore over the
troughs of a series of internal
waves

65. Ecological Succession
Change in an Ecosystem

66. What is Succession?
 The gradual replacement of
one plant community by
another through natural
processes over time.

67. Primary vs. Secondary Succession
 Primary
 The gradual growth of an ecosystem in an area lacking
soil over a long period of time.
 Often takes several hundred to a few thousand years.
 Secondary:
 Occurs when a plant community
has been destroyed without severe
disturbance to the soil.
 Typically much faster but not
always.

68. Primary Succession
• Begins in a place without any soil:
– Sides of volcanoes
– Landslides
– Flooding
• Starts with the arrival of living
things such as lichens that do
not need soil to survive.
• These organisms like lichens are
called PIONEER SPECIES.

69. Secondary Succession
 Secondary Succession is initiated by an event.
 For example: a forest fire, hurricane, or harvesting a crop
 The already-established ecosystem is reduced or drastically
changed.
 Secondary Succession occurs on
land with preexisting soil.

70. STAGES OF ECOLOGICAL
SUCCESSION
 Pioneer Community –First group of organisms
in an area.
 Seral Stage: Various developmental stage