Ecology :- is the study of
organisms in their natural habitat.
It is concerned with the study of
organisms in various habitats like
land, oceans, fresh water and air.
• The word ecology comes from the Greek Oikos,
meaning house or place to live.
• It refers to the study of organisms in their natural
• or the study of the structure and function of
• It is a science which investigates organisms in
relation to their environment.
• study of the relationships that
living organisms have with each other and with
their natural environment
Ecologists seek to explain:
• Life processes and adaptations
• Distribution and abundance of organisms
• The movement of materials
and energy through living communities
• The step by step development of ecosystems,
• The abundance and distribution of
biodiversity in the context of the environment.
Ecology proceeds at three levels
1. The individual organism
At the individual level of organism ecology
deals with how individuals are affected by
and how they affect their environment
2. The population
consisting of individuals of the
same species. At the level of
population, ecology deals with
the presence and absence of
particular species and with trends
and fluctuations in their numbers
3. The community
consisting of number of
populations. Community ecology
deals with the composition or
structure of communities and
with the natural resources
affected by them
• An ecosystem is a complex set of relationships
among living resources, habitat and residents
of a region.
• And Ecology is the scientific study of the
processes influencing the distribution and
abundance of organisms, the interactions
among organisms, and the interactions
between organisms and the transformation
and flux of energy and matter.
“An ecosystem may be defined as
- a system formed by the
interaction of a group of
organisms and their environment
Ecosystem: The collection of all living
organisms in a geographic area, together with
all the living and non-living things with which
· Aquatic Ecosystems (water-based)
· Terrestrial Ecosystems (land-based)
concepts of ecology
2. Cycles & its imbalance
4. Food Chain
5. Carrying Capacity
6. Limiting factor
8. Biological clock
consists of population &
communities of organisms and their
interdependence. It emphasis
relationship & interdependence.
E.g. forest, sea
Ecosystem- dynamic system
Ecosystem is at a constant state of change.
Change can be in its structure and process of
living beings over time. Or changes can be in
its physical environment.
These changes leads to the formation of
different or other ecosystem
Ecosystem is capable of self maintenance
and self regulation.
Human intervention has being the main
cause of imbalance in the ecosystem.
E.g. industrial revolution, green
revolution (intense farming) etc.
Goal for higher rate of productivity has
lead to conflict within the ecosystem.
Our country has a variety of ecosystems
2. Cycles & its imbalance
• Cycles Refers to circulation of elements
like water or carbon in the atmosphere.
This is from environment to organism &
back. E.g. carbon cycle.
• Human activities can upset this cycle
• Recycling & its process is also a part of
cycle. E.g. battery.
• Community where organisms of different
species live together.
• Imbalance is caused when the principle of
interdependence is disrupted. E.g. Extinction
of Dinosaurs or Breeding of Mosquito.
Transfer of food energy from plants through a
series of organisms where eating & being
Pollutants can also be transferred
E.g. ban of DDT
• Every ecosystem has limits in terms of various
populations it can support
• The same concept is applicable to air and
• If the carrying capacity is exceeded by
pollutants it will affect the quality
• E.g. factors such as temperature, light and
water in greater amount than required can
inhibit organisms development
• Government and industry should focus on the
impact of a project on these factors
Habitat refers to place where an
organism, population or community
• The internal clock operates through signals
arising with in the organism or from the
environment like temperature, light, or other
• Changing environmental conditions can
disturb the biological clock
• Resources like oxygen, water, food & other materials
• Cyclic mechanism like water, carbon & nutrient cycle
• Regulatory services like flood, disease & climate control,
temperature regulation & pollination
Any disturbance in ecosystem would lead to breakdown of
For sustainability we have to redesign both our industrial and
• Means application of ecosystem concepts to
• It is based on minimization of raw material usage,
waste production and optimization of energy.
• The concept of closed loop manufacturing system
must be adopted.
• It is a system that integrate profitability with
social and environmental responsibilities
Eg:-many countries in Europe require
manufacturers to follow life cycle thinking
• In Germany under law manufacturers has to
use their products for ever
• E.g. :- INTERFACE worlds largest American
company in manufacturing carpets and other
Extended Producer Responsibility (EPR),
• where producers have a responsibility for their
entire product life cycle including the post
consumer phase of their product, is one
politically feasible way to promote closed loop
• EPR holds product designers responsible for
the environmental and public health impacts
of their products.
The factors affecting ecosystem
• Population growth
• Human activities
• Resources availability
• Climatic factors
• Population growth mainly affects ecosystem
balance, if the number of population
increases, than there exists a resource
• Population growth is the number of
individuals present in each species of
• Two kinds of resources
• Renewable Resources: These types of resources can be
• Non- renewable: These types of resources cannot be
renewed, once used it will not be produced back.
• These resources can be utilized by different species in
the ecosystem, if the population size increases, there
exists a resource shortage.
• Climatic factors such as temperature, rainfall, etc
play the main role in ecological balance.
• Certain animals will exist only in moderate
temperature; if there is high temperature these
species can’t survive leads to extinction.
• Factors such as heavy rainfall, floods, cyclones
and hurricanes lead death to many species
• Human activities like deforestation and
urbanization greatly destroys the habitats of
animals and plants. So that they can’t get the
sufficient resources to exist. They migrate to
other places and some of the species will die .
STRUCTURE OF ECOSYSTEMS
Biotic and Abiotic components
Every ecosystem is composed of two basic
a) Biotic components: the living organisms - all
plant & animals, human beings and microbes
b) Abiotic: the non-living physical and chemical
component consisting of wind, temperature,
water, soil, precipitation etc
Major biological (Biotic) components
of eco system
1. PRODUCERS- Autotrophic components
2. CONSUMERS – Heterotrophic components
3. DECOMPOSERS- saprophytes
1. PRODUCERS: Autotrophic components
includes Green plants, bacteria , algae, and other
organisms that carry on photosynthesis. Producers are
self-nourished – they do not depend on other species
During photosynthesis, plants capture light energy with
their chlorophyll and use it to convert carbon dioxide
and moisture (absorbed from air) into carbohydrates,
protein etc. Oxygen is released as a by-product
Every major ecosystem has its particular green plants
that carry on photosynthesis and release chemical
energy ,on which non-producers feed.
2. CONSUMERS: Heterotrophic components
All other organisms which cannot convert solar
energy into food and depends on autotrophs to
obtain their energy for survival
Consumers are subdivided into groups according
to their food source.
Primary consumers: Species that feed directly on
producers (plant-eating species). They are also
called Herbivores. E.g. elephants, cattle, insects
Secondary Consumers: Species that feed on the
flesh of primary consumers. Secondary and
higher order consumers are called Carnivores.
E.g. fox, cat.
Tertiary and higher level Consumers: Species that
obtain their nourishment by eating other meat-
species. E.g. tiger, lion
Multiple level Consumers: Species that obtain their
nourishment from eating both plants and animal
species. Also called Omnivores
• They are the final link in the food chain.
• Comprise of organisms that feed on dead
matter and break it down to release chemical
energy back into the soil for plants to re-use
• E.g. fungi, bacteria, insects, worms and
• Also called scavengers.
Abiotic components of ecosystem
• All the non-living components of the
environment such as light, temperature,
humidity, moisture, solar radiation and salinity
of soil as well as inorganic and organic
compounds constitute the abiotic components
of the ecosystem.
• The variation in physical factors that a
population can withstand and continue to
thrive in an environment is termed Range of
• The quality of abiotic materials present in an
ecosystem is known as the ‘standing stage’.
• All biotic organisms interact only with the
abiotic components of the environment.
Major Abiotic factors are
Climatic factors- light ,temperature, rainfall,
Topographical factors-altitude, slope and
direction of mountain
Edaphic factors-structure, formation and nature
These factors are considered as
resources and conditions.
• Resources are those factors that can be
consumed or directly utilized by the organism
like nitrogen, potassium etc.
• Environmental conditions are factors that are
not directly utilized by the organism but affect
the growth and survival of the organism
Types of ecosystem
1. Terrestrial ecosystem- includes forest
ecosystem, desert ecosystem, grass land
ecosystem, tree ecosystem, etc.
2. Marine ecosystem e.g.- seas, oceans.
3. Fresh water ecosystem e.g.- ponds, streams,
rivers and lakes.
4. Man-engineered ecosystem:- agriculture
Terrestrial ecosystems are-
• Depending on annual rain fall and its distribution
avrg monthly temperature, annual dry and wet
periods, humidity etc Indian forests can be
classified into 16 different types.
• Different components of the all forest
ecosystems are the same – abiotic components
(Inorganic and organic substances minerals
present in the atmosphere ),biotic components
(producers consumers and decomposers.
• Continental interiors with law rainfall are dominated by
• Grassland comes under terrestrial ecosystem and
occupy about 19% of the earths total surface.
• The abiotic components of grassland ecosystems are
the nutrients of the environment- supplied by carbon
dioxide, water, nitrates, phosphates and sulphates
present in the air and soil of the area
• Biotic components includes producers, consumer sand
decomposers in the grassland
• Continental interiors with very law rainfall and
with very law humidity are converted to
• The species composition is quite different
because of the extreme climatic conditions.
Fresh water ecosystem
• Fresh water ecosystem can be two types
1. Lotic – having flowing water eg streams and
2. Lentic- having stagnant or still water eg
ponds and lakes
The components of a fresh water ecosystem
are self regulating and self sufficient.
The components of an aquatic system can
also be classified into biotic and abiotic.
Abiotic components are carbon dioxide,
oxygen, calcium, nitrogen, phosphorous,
amino acids and water
Biotic components consists of producers
consumers and decomposers.
Marine (ocean) eco system
• Marine ecosystem can be devided into
1. Littoral zone
4. Benthic zone
• Littoral zone- the shore line between the land
and open sea is termed as littoral zone. waves
and tides have the maximum effect in this zone.
• Just above the continental shelf lies the Neritic
zone- this zone is rich in nutrients washed from
land and hence rich in species too. Sunlight also
penetrates the neritic zone. Hence the
productivity of this zone is high. Pollutions affect
this zone first
• Pelagic zone- the open sea constituting 90%
of the total ocean surface forms the pelage
• Photosynthesis is carried out by
phytoplankton's are present in this zone.
• This zone is very large in area, it is low in
nutrients and productivity.
• fin and blue whale are present here
• Benthic zone- the floor of the ocean
constitutes the benthic zone. It streches from
the edge of the continental shelf to the
deepest ocean trenches. Organisms present
here are heterotrophic