Ecology

ECOLOGY
Dr. Rajendra Singh Thakur
Dr. Rajendra Singh Thakur/ ECOLOGY 1

Ecology
 Ecology define as the study of organisms, plants and animal in
relation to other and to their non-living environment.
 The terms Ecology derived from Greek word “Oekologie”
Oekos : home or surround and Logs: Study.
 It can be said that ecology is study of earths households including –
plants, animals, microorganism and human beings lives together
as inter dependant component.
 On basis of study of nature ecology can be sub divided as -
 Autecology - individual organism or species, ex. Neem
 Synecology – group organ which associate together as unit , Forest

SCOPE OF ECOLOGY
 Ecology was consider to be branch of biology that deal with relation of organisms or
group of organisms to their environment.
 Ecology is organisms, plants and animals in energy flow and material cycles on in
lands, ocean, air, fresh water as consider modern emphasis that study of structure
and function of nature.
 The movement of materials is known as biogeochemical cycle ex. Nitrogen &
sulphure cycle etc.
 Focus is on the role of man in degradation of environment and suggest remedies
i.e.
 Ecology mgt. for minimizing the effects of pollution,
 Deforestation,
 Killing of animal life,
 Chemical or biological or nuclear warfare,
 Population explosion and
 Other problems. Dr. Rajendra Singh Thakur/ ECOLOGY 3

ECOSYSTEM
 An ‘Ecosystem’ is a region with a specific and recognizable landscape form such as forest,
grassland, desert, wetland or coastal area.
 The nature of the ecosystem is based on its geographical features such as hills, mountains,
plains, rivers, lakes, coastal areas or islands.
 It is also controlled by climatic conditions such as the amount of sunlight, the
temperature and the rainfall in the region.
 The geographical, climatic and soil characteristics form its non-living (abiotic)
component.
 The living part of the ecosystem is referred to as its biotic component.
 Ecosystems are divided into terrestrial or land based ecosystems, and aquatic ecosystems
in water these form major habitat conditions in communities of plants and animals.
 At a global level the thin skin of the earth on the land, the sea and the air, forms the
biosphere.

 An ecosystem is natural grouping of Nutrients, Minerals, Plants, Animals
and their waste link together by flow of food and Energy from one part to
another
 Ex.- Pond, Grassland, Streams, Cities, Deserts etc.
 An ecosystem can be only few centimeter squire in size like microbial
mats Or
 Its size can be Kilometer like tropical forest.
 It is not only physical structure (i.e. size, shape, variations of borders
etc.)but existence of the processes – the flow of energy and the cycling of
chemical element.

TYPE OF ECOSYSTEM
 Ecosystem depends upon physical and metabolic adoption to the
environment of that place.
 On earth there are sets of ecosystem with in Geographic region
exposed to same climatic conditions and physical structure sets of
ecosystem is called Biome.
 In the Biosphere there are -
1. Natural ecosystems -depend on soil structure, climate, O2,
CO2 & water
a) Terrestrial: include the forests, grasslands, deserts, and
b) Aquatic ecosystems: such as ponds, rivers, lakes, and the sea.
2. Artificial ecosystems- Man modified ecosystems include
agricultural land and urban or industrial land use patterns.

STRUCTURE AND FUNCTIONS OF AN ECOSYSTEM
 Structural aspects- Components that make up the structural aspects of an
ecosystem include:
1) Inorganic aspects – C, N, CO2, H2O.
2) Organic compounds – Protein, Carbohydrates, Lipids – link abiotic to biotic
aspects.
3) Climatic regimes – Temperature, Air, Moisture, Light & Topography.
4) Producers – Plants.
5) Macro consumers – Phagotrophs – Large animals.
6) Micro consumers – Saprotrophs, absorbers – fungi.
 Functional aspects
1) Biological Energy cycles –production and respiration of community.
2) Food chains.
3) Diversity- inter linkages between organisms.
4) Nutrient cycles- biogeochemical cycles.
5) Evolution. Dr. Rajendra Singh Thakur/ ECOLOGY 8

STRUCTURE
 Biotic components are the living things that shape an ecosystem. Each biotic factor needs
energy to do work and food for proper growth. Biotic factors include human influence.
 Biotic components are contrasted to abiotic components, which are non-living components of
an organism's environment, such as temperature, light, moisture, air currents, etc. Remember the
abiotic factors by SWATS (Soil, Water, Air, Temperature, and Sunlight).
 Biotic components usually include:
1. Producers, i.e. autotrophs : e.g. plants, they convert the energy [from photosynthesis (the
transfer of sunlight, water, and carbon dioxide into energy), or other sources such as
hydrothermal vents] into food.
2. Consumers, i.e. heterotrphs: e.g. animals, they depend upon producers (occasionally other
consumers) for food.
3. Decomposers, i.e. detrivores: e.g. fungi and bacteria, they break down chemicals from
producers and consumers (usually dead) into simpler form which can be reused.

 In Abiotic components (also called abiotic factors) are non-living chemical and
physical factors in the environment, which affect ecosystems.
 In biology, abiotic factors can include soil acidity, light, radiation, temperature,
water, atmospheric gases and soil.
 All of these factors affect different organisms to different extents. If there is little or no
sunlight then plants may wither and die from not being able to get enough sunlight to do
photosynthesis.
 For example, there is a significant difference in access to water as well as humidity
between temperate rainforests and deserts. This difference in water access causes a
diversity in the types of plants and animals that grow in these areas.

STRUCTURE MAJOR COMPONENT  The ecosystems have basically two types of components, the biotic and abiotic, as described below:
(a) BIOTIC COMPONENTS:
Different living organisms constitute the biotic component of an ecosystem and belong to
the following categories:
(i) Producers: These are mainly producing food themselves e.g., Green plants produce food by
photosynthesis in the presence of sunlight from raw materials like water and carbon dioxide. They
are known as photo-autotrophs (auto = self, photo = light, troph = food). There are some
chemo-autotrophs, which are a group of bacteria, producing their food from oxidation of certain
chemicals. e.g. sulphur bacteria.
(ii) Consumers: These organisms get their food by feeding on other organisms. They are of the
following types:
 Herbivores— which feed on plants e.g. rabbit, insect.
 Carnivores— which feed on herbivores as secondary carnivores (e.g., frog, small fish) or tertiary
carnivores (e.g., snake, big fish), which feed on other consumers.
 Omnivores— which feed on both plants and animals e.g., humans, rats, many birds.
 Detritivores— which feed on dead organisms e.g., earth worm, crab, ants.
(iii) Decomposers: These are micro-organisms which break down organic matter into
inorganic compounds and in this process they derive their nutrition. They play a very important
role in converting the essential nutrients from unavailable organic form to free inorganic form that
is available for use by plantDs re. R.ga.je, nbdarac Steinrgiha ,T hfuaknugr/i .ECOLOGY 11

(b) ABIOTIC COMPONENTS:
Various physico-chemical components of the ecosystem constitute the abiotic
structure:
(i) Physical components include-
 sunlight,
 solar intensity,
 rainfall,
 temperature,
 wind speed and direction,
 water availability,
 soil texture etc.
(ii) Chemical components include-
 major essential nutrients like C, N, P, K, H2, O2, S etc. and
 micronutrients like Fe, Mo, Zn, Cu etc.,
 salts and toxic substances like pesticides.
(iii) These physico-chemical factors of
 water,
 air and
 soil play an important Dror. lRea jiennd erac Soinsgyhs tTehmaku fru/ EnCcOtLioOnGYing. 12

Cycles in Ecosystems
 Chemical element including all essential element of
protoplasm's tend to circulate in biosphere characteristic
path from environment to organism and organism to
environment path known as “Biogeochemical cycles”
 90 odd element- occur in nature between 30-40 required
for living organism.
 Circulating of mineral (nutrient) in biosphere called mineral
cycling or nutrient cycling.
 These elements in various forms flow from the nonliving
(abiotic) to the living (biotic) components of the biosphere
and back to the nonliving again.
 In order for the living components of a major ecosystem (e.g.,
a lake or forest) to survive, all the chemical elements that
make up living cells must be recycled continuously.
 Important cycles are Carbon, Oxygen, Nitrogen and Water.

The Carbon Cycle
 Carbon also cycles between the
nonliving environment and living
organisms.
 Carbon dioxide in the air or
dissolved in water is used by
photosynthesizing plants, algae,
and bacteria as a raw material to
build organic molecules.
Carbon cycle

The Carbon Cycle:
 Carbon atoms may return to the
pool of carbon dioxide in the air
and water in three ways
 Respiration
 Combustion
 Erosion
Carbon cycle

Respiration:
 Nearly all living organisms,
including plants, engage in
cellular respiration.
 They use oxygen to oxidize
organic molecules during cellular
respiration, and carbon dioxide is
a product of this reaction.
Carbon cycle
The Carbon Cycle

The Carbon Cycle
Combustion:
 Carbon also returns to the
atmosphere through combustion,
or burning.
 The carbon contained in wood
may stay there for many years,
returning to the atmosphere only
when the wood is burned.
 Sometimes carbon can be locked
away beneath the Earth for
millions of years, as in fossil fuels
like oil, coal, and natural gas. The
carbon in these is released when
these fossil fuels are burned. Carbon cycle

Erosion:
 Marine organisms use carbon
dioxide dissolved in sea water to
make calcium carbonate shells.
 Over millions of years, the shells
of dead organisms form
sediments, which form limestone.
 As the limestone becomes
exposed and erodes, the carbon
becomes available to other
organisms.
Carbon cycle
The Carbon Cycle

The Oxygen Cycle
 Oxygen – a colorless, odorless, tasteless gas
 Denser than air
 Poor conductor of heat and electricity
 A biogeochemical cycle is the movement of matter through the biotic and the
abiotic spheres of the ecosystem.
 The oxygen cycle begins with plants and photosynthesis.
 Through photosynthesis, plants convert the energy from the sun and water
into carbohydrates and oxygen.
 During the day: plants convert carbon dioxide into oxygen.
 During the night: plants convert oxygen into carbon dioxide to maintain
their metabolism.

The Oxygen Cycle

Step One of Oxygen Cycle
• Plant release oxygen into the atmosphere
as a by-product of photosynthesis.
oxygen

Step Two of Oxygen Cycle
• Animals take in oxygen through the process
of respiration.
• Animals then break down sugars and food.

Step Three in Oxygen Cycle
• Carbon dioxide is released by animals and
used in plants in photosynthesis.
• Oxygen is balanced between the
atmosphere and the ocean.

Photosynthesis
•Definition- process in which green plants use the energy
from the sun to make carbohydrates from carbon dioxide
and water in the presence of chlorophyll.

Respiration
• Process by which an organism exchanges
gases with its environment
• Process → oxygen is abstracted from air,
transported to cells for the oxidation of
organic molecules while CO2 and H2O,
the products of oxidation, are returned to
the environment

The Nitrogen Cycles
 The atmosphere is about 78 percent
nitrogen gas. However, most organisms
are unable to use it in this form.
 Organisms need nitrogen and
phosphorus to build proteins and
nucleic acids.
 The two nitrogen atoms in a molecule of
nitrogen gas are connected by a strong
triple covalent bond that is very difficult
to break.
 However, a few bacteria have enzymes
that can break it, and they bind nitrogen
atoms to hydrogen to form ammonia.
 The process of combining nitrogen with
hydrogen to form ammonia is called
nitrogen fixation.
 Nitrogen fixing bacteria live in the soil
and are also found within swellings, or
nodules, on the roots of beans, alder
trees, and a few other kinds of plants.

The nitrogen cycle is a complex
process with four stages:
1: Assimilation is the absorption
and incorporation of nitrogen
into organic compounds by
plants
2: Ammonification is the
production of ammonia by
bacteria during the decay of
organic matter.
3: Nitrification is the production
of nitrate from ammonia.
4: Denitrification is the
conversion of nitrate to
nitrogen gas.
Decomposers (bacteria and fungi) carry out many
Important steps in the nitrogen cycle
The Nitrogen Cycles :

 The growth of plants in
ecosystems is often limited by
the availability of nitrate and
ammonia in the soil.
 Today most of the ammonia
and nitrate that farmers add
to soil is produced chemically
in factories, rather than by
bacterial nitrogen fixation.
 Genetic engineers are trying to
place nitrogen-fixing genes
from bacteria into the
chromosomes of crop plants
using genetic engineering.

 If these attempts by genetic
engineers are successful, the
plants themselves will be able
to fix nitrogen, thus
eliminating the need for
nitrogen-supplying
fertilizers.
 Some farmers adjust their
farming methods to increase
natural recycling of nitrogen.

The Water Cycle
 Of all the nonliving components of
an ecosystem, water has the greatest
influence on the ecosystem’s
inhabitants.
 In the nonliving portion of the water
cycle, water vapor in the atmosphere
condenses and falls to Earth’s surface
as precipitation as snow or rain.
 Some of this water seeps into Earth’s
surface (infiltration) and becomes
part of groundwater, which is water
retained beneath the surface of the
Earth.

The Water Cycle:
 Most of the remaining water that
falls to Earth does not stay on the
surface.
 Instead, heated by the sun, it
reenters the atmosphere by
evaporation.
 In the living portion of the water
cycle, much water is taken up by the
roots of plants.
 After passing through a plant, the
water moves into the atmosphere
by evaporating from the leaves, a
process called transpiration.

The Water Cycle:
 Transpiration is a sun driven
process.
 The sun heats the Earth’s
atmosphere, creating wind currents
that draw moisture from the tiny
openings in the leaves of plants.

The Water Cycle:
 In aquatic ecosystems (lakes, rivers
and oceans) the nonliving portion
of the ecosystem is the most
important.
 In terrestrial ecosystems, the
nonliving and living parts of the
water cycle both play important
roles.
 In thickly vegetated ecosystems,
such as tropical rainforests, more
than 90 percent of the moisture in
the ecosystem passes through plants
and is transpired from their leaves.

Condensation
Transpiration
Evaporation
Rain clouds
Precipitation Precipitation
Ocean storage
Transpiration
from plants
Precipitation
to land
Groundwater movement (slow)
Evaporation
from land Evaporation
from ocean Precipitation
to ocean
Infiltration and
Percolation
Runoff
Surface runoff
(rapid)
Surface
runoff
(rapid)

Producers,
Consumers,
Decomposers
Its all about what you eat!

An organism is …..
 Any independent
living thing
 Can be as small as a
single celled bacteria
 Or as large as a
whale!

The three categories of the food
chain are…..
1) Producers
2) Consumers
3) Decomposers
They are all depend on each other.

Producers Are-
 Producers get their
food and energy
from the sun.
(PLANTS)
 They make their food
through a process called
photosynthesis.

Consumers
 Consumers need to
eat their food to get
energy. (ANIMALS)

Types of consumers are
 There are THREE
types of Consumers
Herbivores
Carnivores
Omnivores.
 Its still all about what
you eat!

Herbivores eat only plants.

Carnivores only eat meat (other
animals)

Omnivores eat both meat (animals)
and plants.

Decomposers
 Decomposers eat
dead things and turn
them back into dirt,
or soil.
 Examples:
Mushrooms
Worms
Bugs

Soil Mites
Worms
Fungi

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.
 A food chain starts with the primary energy source, usually the sun or boiling-hot deep sea vents.
 The next link in the chain is an organism that make its own food from the primary energy source -- an example is
photosynthetic plants that make their own food from sunlight (using a process called photosynthesis) and
chemosynthetic bacteria that make their food energy from chemicals in hydrothermal vents. These are
called autotrophs or primary producers.
 Next come organisms that eat the autotrophs; these organisms are called herbivores or primary consumers --
an example is a rabbit that eats grass.
 The next link in the chain is animals that eat herbivores - these are called secondary consumers -- an example is
a snake that eat rabbits.
 In turn, these animals are eaten by larger predators -- an example is an owl that eats snakes.
 The tertiary consumers are are eaten by quaternary consumers -- an example is a hawk that eats owls. Each food
chain end with a top predator, and animal with no natural enemies (like an alligator, hawk, or polar bear).
 The arrows in a food chain show the flow of energy, from the sun or hydrothermal vent to a top predator. As the
energy flows from organism to organism, energy is lost at each step. A network of many food chains is called
a food web.

Trophic Levels
 The trophic level of an organism is the position it holds in a food chain.
 Primary producers (organisms that make their own food from sunlight and/or chemical energy from deep sea
vents) are the base of every food chain - these organisms are called autotrophs.
 Primary consumers are animals that eat primary producers; they are also called herbivores (plant-eaters).
 Secondary consumers eat primary consumers. They are carnivores (meat-eaters) and omnivores (animals
that eat both animals and plants).
 Tertiary consumers eat secondary consumers.
 Quaternary consumers eat tertiary consumers.
 Food chains "end" with top predators, animals that have little or no natural enemies.
 When any organism dies, it is eventually eaten by detrivores (like vultures, worms and crabs) and broken
down by decomposers (mostly bacteria and fungi), and the exchange of energy continues.
 Tow type of Food chains-
1. Grazing Food chains- starts from living green plants goes to grazing herbivores on to carnivores.
2. Detritus Food chains - starts from dead organic matters goes to detritus feeding organism on to predator.

Food Chain

Food Web

Ecology

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