04 Ecosystem

The study of the relationships between biotic and The study of the relationships between biotic and abiotic factors in environmentsabiotic factors in environmentsThe study of the relationships between biotic and The study of the relationships between biotic and abiotic factors in environmentsabiotic factors in environments

Examples of Biotic FactorsExamples of Biotic Factors

Plants Animals

Microorganisms

Abiotic FactorsAll non living components of the environment are All non living components of the environment are abiotic factors. They include air, water, soil, abiotic factors. They include air, water, soil, temperature, rainfall, humidity, minerals, source of temperature, rainfall, humidity, minerals, source of energy.energy.

All non living components of the environment are All non living components of the environment are abiotic factors. They include air, water, soil, abiotic factors. They include air, water, soil, temperature, rainfall, humidity, minerals, source of temperature, rainfall, humidity, minerals, source of energy.energy.

A major regional or global biotic community, a A major regional or global biotic community, a

super ecosystem, defined chiefly by the dominant super ecosystem, defined chiefly by the dominant

forms of plant life and the prevailing climateforms of plant life and the prevailing climate

A major regional or global biotic community, a A major regional or global biotic community, a

super ecosystem, defined chiefly by the dominant super ecosystem, defined chiefly by the dominant

forms of plant life and the prevailing climateforms of plant life and the prevailing climate

BiomeBiome

DesertDesertDesertDesert

GrasslandGrasslandGrasslandGrassland

Tropical rain forestTropical rain forestTropical rain forestTropical rain forest

Deciduous forestDeciduous forestDeciduous forestDeciduous forest

Coniferous forestConiferous forestConiferous forestConiferous forest

TundraTundraTundraTundra

Major Biomes of the WorldMajor Biomes of the World

OceanOceanOceanOcean

04/22/23 Source: Confidential 7

Tropical rain forestTropical rain forestTropical rain forestTropical rain forest


Deciduous forestDeciduous forestDeciduous forestDeciduous forest


Coniferous forestConiferous forestConiferous forestConiferous forest


TundraTundraTundraTundra

Life Organization

Levels of OrganizationLevels of Organization

Levels of OrganizationLevels of Organization

smallest unit of living smallest unit of living thingsthingssmallest unit of living smallest unit of living thingsthingsgroup of similar cells group of similar cells organized to work organized to work togethertogether

group of similar cells group of similar cells organized to work organized to work togethertogether

group of different kinds of group of different kinds of tissues working togethertissues working togethergroup of different kinds of group of different kinds of tissues working togethertissues working togethergroup of organs working group of organs working togethertogethergroup of organs working group of organs working togethertogetherone individual living thingone individual living thingone individual living thingone individual living thingall organisms of the same all organisms of the same kind living in one areakind living in one areaall organisms of the same all organisms of the same kind living in one areakind living in one areaall interacting populations all interacting populations in an ecosystem in an ecosystem all interacting populations all interacting populations in an ecosystem in an ecosystem all living and nonliving all living and nonliving things interacting within a things interacting within a certain area certain area

all living and nonliving all living and nonliving things interacting within a things interacting within a certain area certain area

large region with typical large region with typical plants and animals that plants and animals that includes several includes several ecosystems ecosystems

large region with typical large region with typical plants and animals that plants and animals that includes several includes several ecosystems ecosystems

cell

Ecosystems: Fundamental CharacteristicsFundamental Characteristics

• Structure:– Living (biotic)– Nonliving (abiotic)

• Function:– Energy flow– Cycling of matter

Ecosystem

Structure

Biotic Abiotic

Producers

Consumers

Decomposers

Physical Chemical

Solar flux, Temperature,

Rainfall,

Wind,

Water

Latitude,

Altitude,

Soil type etc

Carbon, Nitrogen, Phosphorus,

Potassium,

Hydrogen,

Oxygen, Salts,

Organic substances in the

soil

Food Chain,

Food web,

Ecological Pyramids,

Bio-geo Chemical Cycles

Ecological Succession

Functions

In an ecosystem the biological cycling of materials is

maintained by three groups

• Producers

• Consumers

• Decomposers / Recyclers

In an ecosystem the biological cycling of materials is

maintained by three groups

• Producers

• Consumers

• Decomposers / Recyclers

Producers, Consumers and Decomposers:

Producers: Autotrophic organisms, largely green plants which are able to manufacture the required food material from simple inorganic substances.

Consumers:Heterotrophic organisms, chiefly animals, which ingest other organisms or particulate organic matter, are included in this category

(i) Primary Consumers – Herbivores(ii) Secondary Consumers – Carnivores(iii) Tertiary Consumers – Carnivores or Omnivores

Producers, Consumers and Decomposers:

Producers: Autotrophic organisms, largely green plants which are able to manufacture the required food material from simple inorganic substances.

Consumers:Heterotrophic organisms, chiefly animals, which ingest other organisms or particulate organic matter, are included in this category

(i) Primary Consumers – Herbivores(ii) Secondary Consumers – Carnivores(iii) Tertiary Consumers – Carnivores or Omnivores

Examples of producers:

Examples of producers:

Photosynthetic Photosynthetic BacteriaBacteria

GrassesGrasses ShrubsShrubs

TreesTrees

Herbivores: Also primary consumers, feed directly

on living plants or plant residues. They have

vegetarian diet.

Herbivores: Also primary consumers, feed directly

on living plants or plant residues. They have

vegetarian diet.

Carnivores: Also secondary/ tertiary consumers, which feed on

consumers, i.e. they have non- vegetarian diet.

They are also called “Predators”

Carnivores: Also secondary/ tertiary consumers, which feed on

consumers, i.e. they have non- vegetarian diet.

They are also called “Predators”

Omnivores: Consumers, which feed on producers as well as on

primary consumers, i.e. they have vegetarian as well as non-

vegetarian diet.

Omnivores: Consumers, which feed on producers as well as on

primary consumers, i.e. they have vegetarian as well as non-

vegetarian diet.

Micro-consumers: Also Saprotrophs/ Detritivores . They are popularly known as decomposers, such as bacteria, fungi, flagellates & actinomyctes.

They feed on organic compounds of dead or living protoplasm of plants and animals for their food and energy

They absorb some of the decomposition or breakdown products & release inorganic compounds (nutrients) in the ecosystem, making them available again to producers.

Micro-consumers: Also Saprotrophs/ Detritivores . They are popularly known as decomposers, such as bacteria, fungi, flagellates & actinomyctes.

They feed on organic compounds of dead or living protoplasm of plants and animals for their food and energy

They absorb some of the decomposition or breakdown products & release inorganic compounds (nutrients) in the ecosystem, making them available again to producers.

Trophic Levels

Primary consumer Primary consumer

Secondary consumer Secondary consumer

Tertiary consumer Tertiary consumer

Decomposers Decomposers

A trophic level is the position occupied by an

organism in a food chain.

A trophic level is the position occupied by an

organism in a food chain.

Producers Producers

ProducersProducers ConsumersConsumers

NUTRIENT POOL

DECOMPOSERS

CARNIVORES

HERBIVORES

PRODUCERSCarbohydrates, fats, proteins, nucleic acids etc.

materialenergy

FLOW OF ENERGYFLOW OF ENERGY

Law of 10%

Solar Energy

Producers

Herbivores

Carnivores

Top Carnivore

1 %

10%

10%

10%

Consumers

Calories

10,000

1,000

100

10

1,00,000

Law of 10% proposed by Lindeman

The transfer of food energy from the producers,

through a series of organisms (herbivores,

carnivores and decomposers) with repeated

eating and being eaten, is known as food chain.

1. Grazing food chain

2. Detritus food chain

Food ChainsFood Chains

Maple tree leaves

Cricket

Dead maple leaves

Bacteria, archaea

RobinEarthworm

Robin Cooper’s hawk

Cooper’s hawk

Grazingfood chain

Decomposerfood chain

Feedingstrategy

Trophiclevel

Quaternaryconsumer

5

Tertiaryconsumer

4

Secondaryconsumer3

Primaryproducer

2

1

Primarydecomposeror consumer

Grazing Food Chain

This food chain starts from the living green plants and goes to grazing herbivores and onto carnivores.

These chains are extremely important from energy stand point.

Grass Rabbit Fox Lion

Food chains in natural conditions never operate as isolated sequences, but are inter connected with each other forming a sort of inter locking pattern, which is referred to as food web.

The linear arrangement of food chains hardly occurs and they are interconnected under natural conditions, thus there are found alternatives in nature.

In a grazing food chain of grassland, in the absence of rabbit, grass may also eaten by mouse. The mouse may in turn be eaten directly by hawk or by snake first which is then eaten by hawk.

Food chains in natural conditions never operate as isolated sequences, but are inter connected with each other forming a sort of inter locking pattern, which is referred to as food web.

The linear arrangement of food chains hardly occurs and they are interconnected under natural conditions, thus there are found alternatives in nature.

In a grazing food chain of grassland, in the absence of rabbit, grass may also eaten by mouse. The mouse may in turn be eaten directly by hawk or by snake first which is then eaten by hawk.

Food Webs:Food Webs:Food Webs:Food Webs:

4. Grass Mouse Hawk

5. Grass Mouse Snake Hawk

3. Grass Rabbit Hawk (Vulture/Fox/Man)

1. Grass Grasshopper Hawk

A balanced ecosystem is essential for the survival of all living organisms of the system.

Thus food chains and food webs form a natural natural check to balancecheck to balance the ecosystem.

Apr 22, 2023 Environmental Studies 37

The graphical representation of the trophic structure and

trophic function is referred to as “Ecological Pyramids”

In this, producer level forms the base and

successive levels or tiers make up the apex. Ecological

pyramids may be of 3 general types:

Ecological PyramidsEcological Pyramids

1. The Pyramid of Numbers2. The Pyramid of Biomass3. The Pyramid of Energy

1. The Pyramid of Numbers2. The Pyramid of Biomass3. The Pyramid of Energy

The pyramids of numbers and biomass may be upright (or) inverted depending upon the nature of food chain in the particular ecosystem but the pyramids of energy are always upright.

Pyramid of NumbersGives the relationship between producers, herbivores and carnivores at successive trophic levels in terms of their numbers.

Pyramid of Biomass: To produce a pyramid of biomass the dry weight of each species present is calculated.

Pyramid of Energy: In this pyramid, the number and weight of organisms at any trophic level depends on the rate at which food is being produced but not on the amount of fixed energy at any level in a given time.

Cycling of Matter: by Biogeochemical cyclesCycling of Matter: by Biogeochemical cycles

Hydrological cycle

Carbon cycle

Nitrogen cycle

Phosphorous cycle

Sulfur cycle

Hydrological cycle

Carbon cycle

Nitrogen cycle

Phosphorous cycle

Sulfur cycle


The Water Cycle (Hydrologic cycle)

Carbon cycleCarbon cycle

Nitrogen cycleNitrogen cycle

Natural

Terrestrial

Forest Desert

Aquatic

Grassland Freshwater Estuaries Marine

Lentic

Eg: Ponds, Lakes

Lotic

Eg:Rivers canals, streams

Types of EcosystemTypes of

Ecosystem

Man-Made


On the basis of particular type of habitat, they are further sub divided as: Terrestrial Ecosystems (Biomes): They are often defined by the vegetation types that dominate the

community. Terrestrial vegetation has a rapid exchange of oxygen, water & carbon

dioxide. Moisture is the major limiting factor, faces the problem of dehydration. Examples of terrestrial ecosystem are: Forest ecosystem, Grassland ecosystem, Desert ecosystem.

On the basis of particular type of habitat, they are further sub divided as: Terrestrial Ecosystems (Biomes): They are often defined by the vegetation types that dominate the

community. Terrestrial vegetation has a rapid exchange of oxygen, water & carbon

dioxide. Moisture is the major limiting factor, faces the problem of dehydration. Examples of terrestrial ecosystem are: Forest ecosystem, Grassland ecosystem, Desert ecosystem.

Types of Ecosystem

Types of Ecosystem

Aquatic Ecosystems (Biomes): Aquatic ecosystems deal with biotic community present in water bodies. In terrestrial ecosystem, carbon dioxide and oxygen are present in gaseous

form, but in aquatic ecosystem these are made available in dissolved state.

Aquatic Ecosystems (Biomes): Aquatic ecosystems deal with biotic community present in water bodies. In terrestrial ecosystem, carbon dioxide and oxygen are present in gaseous

form, but in aquatic ecosystem these are made available in dissolved state.

Aquatic ecosystems fall into two categories: Freshwater Ecosystem and Marine Ecosystem. Freshwater ecosystem may be:

Lotic (Running water) Example: Streams, Rivers, Springs

Lentic (Standing water) Examples: Lakes, ponds, swamps

Marine ecosystems includes Deep sea and Oceans.

Aquatic ecosystems fall into two categories: Freshwater Ecosystem and Marine Ecosystem. Freshwater ecosystem may be:

Lotic (Running water) Example: Streams, Rivers, Springs

Lentic (Standing water) Examples: Lakes, ponds, swamps

Marine ecosystems includes Deep sea and Oceans.


Ecological SuccessionEcological Succession

• Ecological succession is the gradual process by which

ecosystems change and develop over a period of

time.

• In the process of succession, the species present in

an area will gradually change.

• Ecological succession is the gradual process by which

ecosystems change and develop over a period of

time.

• In the process of succession, the species present in

an area will gradually change.

There are two types of ecological succession:1. Primary Succession2. Secondary Succession

There are two types of ecological succession:1. Primary Succession2. Secondary Succession

04 Ecosystem

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