Ecosystem is defined as a structural and functional unit of biosphere or segment of nature consisting of community of living beings and the physical environment both interacting and exchanging materials between them.

Definition : Ecosystem is the basic functional unit in ecology.

Ecology is the study of the relationship of plants and animals to their physical and biological environment.

The physical environment includes light and heat or solar radiation, moisture, wind, oxygen, carbondioxide, nutrients in soil, water, and atmosphere.

The biological environment includes organisms of the same kind as well as other plants and animals.The term 'ecosystem' was coined by A.G. Tansley

Ecosystem is defined as a structural and functional unit of biosphere or segment of nature consisting of community of living beings and the physical environment both interacting and exchanging materials between them.

Definition : Ecosystem is the basic functional unit in ecology.

Ecology is the study of the relationship of plants and animals to their physical and biological environment.

The physical environment includes light and heat or solar radiation, moisture, wind, oxygen, carbondioxide, nutrients in soil, water, and atmosphere.

The biological environment includes organisms of the same kind as well as other plants and animals.The term 'ecosystem' was coined by A.G. Tansley

Odum (1971) defined Ecosystem as a unit that includes all of the organisms in a given area interacting with the physical environment, so that a flow of energy leads to clearly defined trophic structure (Trophe = nourishment) .

Odum (1971) defined Ecosystem as a unit that includes all of the organisms in a given area interacting with the physical environment, so that a flow of energy leads to clearly defined trophic structure (Trophe = nourishment) .

Structure of Ecosystem:Each ecosystem has two main components:1. Abiotic components : The nonliving factors or the physical environment prevailing in an ecosystem form the abiotic components. They are mainly of two types:

(a) Climatic factors: Rain, temperature, light, wind, humidity.etc

(b) Edaphic factors: Soil, pH, Minerals, Topography.

Structure of Ecosystem:Each ecosystem has two main components:1. Abiotic components : The nonliving factors or the physical environment prevailing in an ecosystem form the abiotic components. They are mainly of two types:

(a) Climatic factors: Rain, temperature, light, wind, humidity.etc

(b) Edaphic factors: Soil, pH, Minerals, Topography.

2. Biotic components: The living organisms including plants,

animals, and micro-organisms (Bacteria and fungi) that are present in an ecosystem.

On the basis of their role in ecosystem they are classified into three main groups:

1) Producers 2) consumers 3 ) Decomposers.

2. Biotic components: The living organisms including plants,

animals, and micro-organisms (Bacteria and fungi) that are present in an ecosystem.

On the basis of their role in ecosystem they are classified into three main groups:

1) Producers 2) consumers 3 ) Decomposers.

Definitions

Habitat - The physical and biological surroundings needed for survival, which include food, shelter, water, and space

Producer - Any organism that can photosynthesize.

Consumer - An organism that cannot make its own energy but must acquire it by eating green plants or other consumers.

Decomposer - An organism that helps to breakdown and decay dead organisms and animal waste products, thereby returning nutrients into the soil.

The producers are plants and some bacteria capable of producing their own food photosynthetically or by chemical synthesis.

Autotrophs : (autotrophic = self-nourishing)

Green plants fix radiant energy in the presence of the green pigment, chlorophyll, and with the help of minerals (C, H, O, N, P, Ca, Mg, Zn, Fe etc.) taken from their soil and aerial environment ,they build up complex organic matter (carbohydrates, fats, amino acids, proteins, nucleic acids etc).

So green plants are also called as converters (or) transducers

Therefore, autotrophs are called producers.

The producers are plants and some bacteria capable of producing their own food photosynthetically or by chemical synthesis.

Autotrophs : (autotrophic = self-nourishing)

Green plants fix radiant energy in the presence of the green pigment, chlorophyll, and with the help of minerals (C, H, O, N, P, Ca, Mg, Zn, Fe etc.) taken from their soil and aerial environment ,they build up complex organic matter (carbohydrates, fats, amino acids, proteins, nucleic acids etc).

So green plants are also called as converters (or) transducers

Therefore, autotrophs are called producers.

The consumers are animals that obtain their energy and protein directly by grazing , feeding on other animals, or both.

Heterotrophs: (heterotrophic = other - nourishing)

The radiant energy is transferred to various other trophic levels like consumers.

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

The consumers are animals that obtain their energy and protein directly by grazing , feeding on other animals, or both.

Heterotrophs: (heterotrophic = other - nourishing)

The radiant energy is transferred to various other trophic levels like consumers.

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

Macroconsumers: eg: They are of three types :viz., primary consumers eg: herbivores, secondary consumers eg: carnivores tertiary consumers eg: Carnivores and Omnivores (Phagotrophs).

Microconsumers It includes parasites, detritivores and decomposers.

Macroconsumers: eg: They are of three types :viz., primary consumers eg: herbivores, secondary consumers eg: carnivores tertiary consumers eg: Carnivores and Omnivores (Phagotrophs).

Microconsumers It includes parasites, detritivores and decomposers.

Detritivores are scavengers which feed on dead plants and animals or their waste. They are essential for

recycling of nutrients: without them dead plant material would not be

returned to the soil for new growth.

Detritivores are scavengers which feed on dead plants and animals or their waste. They are essential for

recycling of nutrients: without them dead plant material would not be

returned to the soil for new growth.

omnivoreHerbivore Carnivore

1. Parasites: They obtain food directly from other organism of all trophic levels. Parasites cause disease and depend on the host for food.

2. Detrivores and Scavengers: Detrivores (e.g., termites, earth worms, wood lice, millipede etc) feed on organic fragments whereas, scavengers (e.g., vulture, carrion beetle) feed on dead bodies.

Scavengers and detrivores seem to be essential for quick breakdown of dead bodies of organisms.

3. Decomposers: They are mostly parasitic and saprophytic bacteria, actinomycetes and fungi.

1. Parasites: They obtain food directly from other organism of all trophic levels. Parasites cause disease and depend on the host for food.

2. Detrivores and Scavengers: Detrivores (e.g., termites, earth worms, wood lice, millipede etc) feed on organic fragments whereas, scavengers (e.g., vulture, carrion beetle) feed on dead bodies.

Scavengers and detrivores seem to be essential for quick breakdown of dead bodies of organisms.

3. Decomposers: They are mostly parasitic and saprophytic bacteria, actinomycetes and fungi.

The dead organic matter comprising plant and animal material is then broken down by decomposers (bacteria and fungi) into simple inorganic substances. They are cycled back to the soil and the atmosphere and are available to primary producers.

Nature is capable of sustaining the producer – consumer – decomposer cycle indefinitely with the sun as the energy source.

An organism feeding position in an ecosystem is its trophic level.

Thus, an ecosystem may be very extensive covering millions of km2 .

The dead organic matter comprising plant and animal material is then broken down by decomposers (bacteria and fungi) into simple inorganic substances. They are cycled back to the soil and the atmosphere and are available to primary producers.

Nature is capable of sustaining the producer – consumer – decomposer cycle indefinitely with the sun as the energy source.

An organism feeding position in an ecosystem is its trophic level.

Thus, an ecosystem may be very extensive covering millions of km2 .

(I) The composition of biological community including species (plants, animals and microbes), biomass, life cycles and distribution in space, trophic standpoint.

(ii) The quantity, distribution and cycling of the non-living materials such as major and micronutrients, trace elements and water

(iii) The range (or) gradient of conditions like temperature, light, rainfall, relative humidity, wind and topography

(I) The composition of biological community including species (plants, animals and microbes), biomass, life cycles and distribution in space, trophic standpoint.

(ii) The quantity, distribution and cycling of the non-living materials such as major and micronutrients, trace elements and water

(iii) The range (or) gradient of conditions like temperature, light, rainfall, relative humidity, wind and topography

Detrivore- TermiteScavenger -Vulture

Bacteria

Fungi Parasites

HerbivoresHerbivores

Some animals do not eat other animals. They survive on plants and are known as “herbivores”.

Some animals do not eat other animals. They survive on plants and are known as “herbivores”.

CarnivoresCarnivores

Some animals, like the kingfisher, eat only other animals. These animals are called “carnivores”.

Some animals, like the kingfisher, eat only other animals. These animals are called “carnivores”.

OmnivoresOmnivores

Some animals, like us, eat both plants and animals.

These animals are called “omnivores”.

Some animals, like us, eat both plants and animals.

These animals are called “omnivores”.

ConsumersConsumers

“Consume” means “eat”.Animals are consumers because they

“eat” (consume) food provided by plants or other animals.

“Consume” means “eat”.Animals are consumers because they

“eat” (consume) food provided by plants or other animals.

PredatorPredator

A predator eats other animals.A predator eats other animals.

Cats eat fish. So do bears!

PredatorPredator

The cat is a predator, because it eats other animals.

The bear is a predator, because it eats other animals.

People are predators too!

The cat is a predator, because it eats other animals.

The bear is a predator, because it eats other animals.

People are predators too!

PreyPrey

Any animal which is hunted and killed by another animal for food is prey.

Any animal which is hunted and killed by another animal for food is prey.

Predator

Prey

Predators and PreyPredators and Prey

Some animals are predators, some are prey - some are both.

The predator eats the prey, and the prey gets eaten by the predator.

Function of Ecosystem: i) Flow of Energy: The rate of biological energy flow

community varies. (ii) Nutrient Cycling: Rate of materials

(or) nutrient cycles (iii) Biological (or) Ecological

regulation which includes regulation of organisms by environment (eg: Photoperiodism) and regulation of environment by organisms (nitrogen fixation by organisms).

Function of Ecosystem: i) Flow of Energy: The rate of biological energy flow

community varies. (ii) Nutrient Cycling: Rate of materials

(or) nutrient cycles (iii) Biological (or) Ecological

regulation which includes regulation of organisms by environment (eg: Photoperiodism) and regulation of environment by organisms (nitrogen fixation by organisms).

Energy Flow in an Ecosystem

Energy Flow in an Ecosystem

Energy flow is the movement of energy through an ecosystem from the external environment through a series of organism and back to the external environment.

Ecosystem is maintained by the flow of energy.

With the exception of chemosynthetic bacteria all other autotrophs obtain energy from the sun. They trap the light energy and convert it into chemical energy of organic compounds during the process of photosynthesis.

The amount of energy trapped varies from ecosystem to ecosystem.

Energy flow is the movement of energy through an ecosystem from the external environment through a series of organism and back to the external environment.

Ecosystem is maintained by the flow of energy.

With the exception of chemosynthetic bacteria all other autotrophs obtain energy from the sun. They trap the light energy and convert it into chemical energy of organic compounds during the process of photosynthesis.

The amount of energy trapped varies from ecosystem to ecosystem.

Energy flowEnergy flow

Producers Consumers

Decomposer

Heat

heat

Heat

Energy transfers among trophic levels

Energy transfers among trophic levels

How much energy is passed from one trophic level to the next?

How much energy is passed from one trophic level to the next?

Energy loss between trophic levels

Energy loss between trophic levels

Primary productivityPrimary productivity

Primary productivity is the rate of energy capture by producers.

= the amount of new biomass of producers, per unit time and space

Primary productivity is the rate of energy capture by producers.

= the amount of new biomass of producers, per unit time and space

Flow of EnergyFlow of Energy

Aquatic ecosystem = 0. 2% Terrestrial ecosystem, = 1. 0% Grassland = 1. 15% Mixed forest = 0. 8% Crops = 5. 0% C4 plants (sugarcane ) = 10 - 12%

The autotrophs consume a part of the trapped energy, during their growth and metabolism. The remaining is used in their body building.

The heterotrophs depend upon the autotrophs for

obtaining organic compounds and energy contained in them.

Aquatic ecosystem = 0. 2% Terrestrial ecosystem, = 1. 0% Grassland = 1. 15% Mixed forest = 0. 8% Crops = 5. 0% C4 plants (sugarcane ) = 10 - 12%

The autotrophs consume a part of the trapped energy, during their growth and metabolism. The remaining is used in their body building.

The heterotrophs depend upon the autotrophs for

obtaining organic compounds and energy contained in them.

The energy is used for their growth and maintenance. There is always loss of energy at each step of its transfer.

Some energy is degraded into heat and dissipated(wasted)

Thus, the flow of energy in the ecosystem is always unidirectional.

The flow of energy follows the two laws of Thermodynamics:

1st law of Thermodynamics states that energy can neither be created nor be destroyed but it can be transformed from one form to another. .

The energy is used for their growth and maintenance. There is always loss of energy at each step of its transfer.

Some energy is degraded into heat and dissipated(wasted)

Thus, the flow of energy in the ecosystem is always unidirectional.

The flow of energy follows the two laws of Thermodynamics:

1st law of Thermodynamics states that energy can neither be created nor be destroyed but it can be transformed from one form to another. .

Approximately 10% of the energy at each trophic level is transferred to the next trophic level; 90% loss due to...

energy used by the organisms at lower level; lost as heat some biomass at lower levels not consumed -> decomposers

undigested material -> decomposers

Approximately 10% of the energy at each trophic level is transferred to the next trophic level; 90% loss due to...

energy used by the organisms at lower level; lost as heat some biomass at lower levels not consumed -> decomposers

undigested material -> decomposers

Nutrient CyclingNutrient Cycling

(2) Nutrient Cycling: Rate of materials (or) nutrient cycles

Bio-Geo-Chemical Cycles: There are about 40 chemical elements considered to be

essential for living organisms. They are of two varieties:

(i) Sedimentary cycles : In sedimentary cycles the main reservoir is the soil;

The sedimentary and other types of rocks of earth's crust.

(ii) Gaseous cycles: They have their main reservoir of nutrients in the atmosphere and oceans. Examples are the oxygen cycle, carbon cycle, nitrogen cycle etc. Both cycles involve the biotic and abiotic systems

(2) Nutrient Cycling: Rate of materials (or) nutrient cycles

Bio-Geo-Chemical Cycles: There are about 40 chemical elements considered to be

essential for living organisms. They are of two varieties:

(i) Sedimentary cycles : In sedimentary cycles the main reservoir is the soil;

The sedimentary and other types of rocks of earth's crust.

(ii) Gaseous cycles: They have their main reservoir of nutrients in the atmosphere and oceans. Examples are the oxygen cycle, carbon cycle, nitrogen cycle etc. Both cycles involve the biotic and abiotic systems

Nutrient cycleNutrient cycle

Biogeochemical cycles are the circulation pathways of elements (e.g., carbon, oxygen, hydrogen, nitrogen or mineral elements) through the biotic and abiotic components of an ecosystem.

A reservoir is that portion of the earth that acts as a storehouse for the element.

An exchange pool is the portion of the environment from which producers take chemicals, such as the atmosphere or soil.

The biotic community is the pathway (i.e., food chains) through which chemicals move.

Some cycles are primarily gaseous cycles (carbon and nitrogen); others are sedimentary cycles, (phosphorus).

Biogeochemical cycles are the circulation pathways of elements (e.g., carbon, oxygen, hydrogen, nitrogen or mineral elements) through the biotic and abiotic components of an ecosystem.

A reservoir is that portion of the earth that acts as a storehouse for the element.

An exchange pool is the portion of the environment from which producers take chemicals, such as the atmosphere or soil.

The biotic community is the pathway (i.e., food chains) through which chemicals move.

Some cycles are primarily gaseous cycles (carbon and nitrogen); others are sedimentary cycles, (phosphorus).

In an Ecosystem biological cycling of materials is maintained by three groups viz. Producers, consumers, and decomposers/recyclers.

The two ecological processes of energy flow and mineral cycling involving interaction between the physico -chemical environment and the biotic communities is considered as the 'heart' of ecosystem.

Energy flow is always in non-cyclic manner (unidirectional) from sun to the decomposers via producers and macro consumers.

But minerals keep on moving in a cyclic manner

In an Ecosystem biological cycling of materials is maintained by three groups viz. Producers, consumers, and decomposers/recyclers.

The two ecological processes of energy flow and mineral cycling involving interaction between the physico -chemical environment and the biotic communities is considered as the 'heart' of ecosystem.

Energy flow is always in non-cyclic manner (unidirectional) from sun to the decomposers via producers and macro consumers.

But minerals keep on moving in a cyclic manner

OXYGEN CYCLEOXYGEN CYCLE

The water cycle The water cycle involves the movement of

water from the sea, through the atmosphere, over and through the land, and back to the sea. On the way water passes through industry, houses, animals and people. Humans and animals are made of 70% water.

The carbon cycle The carbon cycle involves the movement of

carbon from the air, into plants, animals, people, the earth, and back into the air. It also includes the mining and release of carbon that was trapped in the bodies of ancient plants and animals.

The water cycle The water cycle involves the movement of

water from the sea, through the atmosphere, over and through the land, and back to the sea. On the way water passes through industry, houses, animals and people. Humans and animals are made of 70% water.

The carbon cycle The carbon cycle involves the movement of

carbon from the air, into plants, animals, people, the earth, and back into the air. It also includes the mining and release of carbon that was trapped in the bodies of ancient plants and animals.

WATER CYCLEWATER CYCLE

CARBON CYCLECARBON CYCLE

NITROGEN CYCLENITROGEN CYCLE

PHOSPHORUS CYCLEPHOSPHORUS CYCLE

PHOSPHORUS CYCLEPHOSPHORUS CYCLE

Ecosystem RegulationEcosystem Regulation All ecosystems regulate and maintain

themselves under a set of environmental conditions.

Any stress tries to disturb the normal ecosystem functions , the ecosystem, by itself, tries to resist the change and maintain itself in equilibrium with the environment due to a property known as homeostasis.

Ecosystem maintains a functional balance between various components. This phenomenon is called homoeostasis.

All ecosystems regulate and maintain themselves under a set of environmental conditions.

Any stress tries to disturb the normal ecosystem functions , the ecosystem, by itself, tries to resist the change and maintain itself in equilibrium with the environment due to a property known as homeostasis.

Ecosystem maintains a functional balance between various components. This phenomenon is called homoeostasis.

It is achieved by a number of limitations, which is called cybernetics.

For example generally no species increases its number beyond the limit thus it controls own growth in response to scarcity of resources and overcrowding.

It is achieved by a number of limitations, which is called cybernetics.

For example generally no species increases its number beyond the limit thus it controls own growth in response to scarcity of resources and overcrowding.

Food chainsFood chains

The transfer of food energy from the source in plants (producers) through a series of organism (herbivores) to carnivores to decomposers) with repeated stages of eating and being eaten is known as food chain.

All organisms, living or dead, are potential food for some other organism and thus, there is essentially no waste in the functioning of a natural ecosystem.

Some common examples of simple food chains are:

The transfer of food energy from the source in plants (producers) through a series of organism (herbivores) to carnivores to decomposers) with repeated stages of eating and being eaten is known as food chain.

All organisms, living or dead, are potential food for some other organism and thus, there is essentially no waste in the functioning of a natural ecosystem.

Some common examples of simple food chains are:

Grass —> grasshopper —> Frog —> Snake —> Hawk (Grassland ecosystem)

Phytoplanktons —> water fleas —> small fish —> Tuna (Pond ecosystem)

Each organism in the ecosystem is assigned a feeding level or trophic level depending on its nutritional status.

Grass —> grasshopper —> Frog —> Snake —> Hawk (Grassland ecosystem)

Phytoplanktons —> water fleas —> small fish —> Tuna (Pond ecosystem)

Each organism in the ecosystem is assigned a feeding level or trophic level depending on its nutritional status.

Types of food chainsTypes of food chains 1. Grazing food chain: It starts with green plants

(primary producers) and culminates in carnivores. Example :

Grass —> Rabbit —> Fox Phytoplankton —> Zooplantkton —> Fish —> Man Grass —> Grasshopper —>frog —> snake —> Hawk Ecosystems of such type of food chains are directly

dependent on an influx of solar energy.

2. Detritus food chain: It starts with dead organic matter which the detritivores and decomposers consume.

Partially decomposed dead organic matter and even the decomposers are consumed by detrivores and their predators.

Example - Mangrove and estuarine areas. Dead organic matter —> Detrivores —>predators. Fallen leaves and dead plants —>soil mites —> Insects

—> Fish.

1. Grazing food chain: It starts with green plants (primary producers) and culminates in carnivores. Example :

Grass —> Rabbit —> Fox Phytoplankton —> Zooplantkton —> Fish —> Man Grass —> Grasshopper —>frog —> snake —> Hawk Ecosystems of such type of food chains are directly

dependent on an influx of solar energy.

2. Detritus food chain: It starts with dead organic matter which the detritivores and decomposers consume.

Partially decomposed dead organic matter and even the decomposers are consumed by detrivores and their predators.

Example - Mangrove and estuarine areas. Dead organic matter —> Detrivores —>predators. Fallen leaves and dead plants —>soil mites —> Insects

—> Fish.

Detritus Food Chain

Grazing Food Chain

Food web is a network of food chains where different types of organisms are connected at different trophic levels, so that there are a number of options of eating and being eaten at each trophic level.

In ecosystems, some consumers feed on a single species, but most consumers have multiple food sources.

In this way, linear individual food chains interconnect to form a food web.

Food web is a network of food chains where different types of organisms are connected at different trophic levels, so that there are a number of options of eating and being eaten at each trophic level.

In ecosystems, some consumers feed on a single species, but most consumers have multiple food sources.

In this way, linear individual food chains interconnect to form a food web.

FOOD WEBFOOD WEB

ECOLOGICAL PYRAMIDSECOLOGICAL PYRAMIDS

Graphic representation of trophic structure and function of an ecosystem, starting with producers at the base and successive trophic levels forming the apex is knows as an ecological pyramid.

Graphic representation of trophic structure and function of an ecosystem, starting with producers at the base and successive trophic levels forming the apex is knows as an ecological pyramid.

Ecological pyramids are of three types:

Pyramid of Numbers:Pyramid of Biomass: Pyramid of Energy:

Ecological pyramids are of three types:

Pyramid of Numbers:Pyramid of Biomass: Pyramid of Energy:

Pyramid of NumbersPyramid of Numbers

It represents the number of individual organisms at each trophic level. It may be upright or inverted pyramid of numbers, depending upon the type of ecosystem and food chain

A grassland ecosystem and a pond ecosystem show an upright pyramid of numbers

It represents the number of individual organisms at each trophic level. It may be upright or inverted pyramid of numbers, depending upon the type of ecosystem and food chain

A grassland ecosystem and a pond ecosystem show an upright pyramid of numbers

Pyramid of Numbers a) Grassland b) forest c) parasitic food chain

Pyramid of Numbers a) Grassland b) forest c) parasitic food chain

Pyramid of biomassPyramid of biomass

It is based upon the total biomass (dry matter) at each trophic level in a food chain.

The pyramid of biomass can also be upright or inverted. The pyramid of biomass in a forest is upright. The pond ecosystem shows an inverted pyramid of biomass.

a) Grassland ecosystem b) pond ecosystem

It is based upon the total biomass (dry matter) at each trophic level in a food chain.

The pyramid of biomass can also be upright or inverted. The pyramid of biomass in a forest is upright. The pond ecosystem shows an inverted pyramid of biomass.

a) Grassland ecosystem b) pond ecosystem

Pyramid of BiomassPyramid of Biomass

Pyramid of EnergyPyramid of Energy

The amount of energy present at each trophic level is considered for this type of pyramid. Pyramid of energy is always upright.

At every successive trophic level, there is a huge loss of energy (about 90%) in the form of heat, respiration etc.

Thus, at each next higher level only 10% of the energy passes on. Hence, there is a sharp decline in energy level of each successive trophic level as we move from Producers to top carnivores

The amount of energy present at each trophic level is considered for this type of pyramid. Pyramid of energy is always upright.

At every successive trophic level, there is a huge loss of energy (about 90%) in the form of heat, respiration etc.

Thus, at each next higher level only 10% of the energy passes on. Hence, there is a sharp decline in energy level of each successive trophic level as we move from Producers to top carnivores

Types of Ecosystem:Types of Ecosystem: The world's major different habitat types. 1. Terrestrial ecosystems: Include Arctic and alpine

ecosystems, dominated by cold areas and lacking trees; forest ecosystems, which can be subdivided into a whole range of types including tropical rainforests, Mediterranean evergreen forests, temperate and boreal forests, and temperate deciduous forests; grasslands and savannahs; and deserts and semi-arid ecosystems.

2. Freshwater ecosystems: Include lakes, rivers, and marshland. "Hybrid" terrestrial and freshwater systems include swamp forests and seasonal floodplains.

3. Marine ecosystems: Include an enormous range, from coral reefs, mangroves, sea-grass beds, and other coastal and shallow water ecosystems to open-water ecosystems and the

mysterious, little-known systems of the abyssal plains and trenches of the world's oceans.

The world's major different habitat types. 1. Terrestrial ecosystems: Include Arctic and alpine

ecosystems, dominated by cold areas and lacking trees; forest ecosystems, which can be subdivided into a whole range of types including tropical rainforests, Mediterranean evergreen forests, temperate and boreal forests, and temperate deciduous forests; grasslands and savannahs; and deserts and semi-arid ecosystems.

2. Freshwater ecosystems: Include lakes, rivers, and marshland. "Hybrid" terrestrial and freshwater systems include swamp forests and seasonal floodplains.

3. Marine ecosystems: Include an enormous range, from coral reefs, mangroves, sea-grass beds, and other coastal and shallow water ecosystems to open-water ecosystems and the

mysterious, little-known systems of the abyssal plains and trenches of the world's oceans.

Arctic ecosystem

Fresh water EcosystemFresh water Ecosystem

Fresh water - LakeFresh water - Lake

Coral reefsCoral reefs

Seagrass bedsSeagrass beds

Seagrass bedsSeagrass beds

Major Terrestrial biomes Major Terrestrial biomes

Figure 34.9

30º N

Equator

30º S

Tropical forest

Savanna

Desert

Polar and high-mountain ice

Chaparral

Temperate grassland

Temperate deciduous forest

Coniferous forest

Tundra (arctic and alpine)

TYPES OF FORESTTYPES OF FOREST

There are three major types of forests:  Tropical, Temperate, and arctic. 

Each of these major forest types have other groups of forests that are named because of the weather and seasons they have.

There are three major types of forests:  Tropical, Temperate, and arctic. 

Each of these major forest types have other groups of forests that are named because of the weather and seasons they have.

Tropical forests cluster near the equator

TEMPERATE FOREST

ARCTIC FOREST

Tropical forests• Have the greatest diversity of species (lots of birds, small mammals, and insects) • •Located near the equator (an imaginary line around the Earth forming the great circle that is equidistant from the north and south poles)

• There is no winter and these forests only have 2 seasons: rainy and dry 12 hours of daylight

• Temperature is about the same all year around (68°F to 77°F) • • Average rainfall is more than 78 inches per year • •1 square kilometer may contain more than 100 species of trees Soil is not nutrient rich

Types of tropical forestsTypes of tropical forests Evergreen rainforest: no dry season.

Seasonal rainforest: short dry period

Semi-evergreen forest: longer dry season (has both deciduous and evergreen trees )

Moist/dry deciduous forest (monsoon): the length of the dry season increases further as rainfall decreases (all trees are deciduous).

(Evergreen trees are always green and never

lose their leaves or needles, i.e. pine tree.  Deciduous trees drop their leaves, i.e. maple trees.)

Evergreen rainforest: no dry season.

Seasonal rainforest: short dry period

Semi-evergreen forest: longer dry season (has both deciduous and evergreen trees )

Moist/dry deciduous forest (monsoon): the length of the dry season increases further as rainfall decreases (all trees are deciduous).

(Evergreen trees are always green and never

lose their leaves or needles, i.e. pine tree.  Deciduous trees drop their leaves, i.e. maple trees.)

Temperate forestsTemperate forests Located in eastern North America, northeastern Asia, and

western and central Europe Have winter and other seasons

Temperature varies from -22°F to 86°F

Rainfall occurs throughout the year, averages 30 to 60 inches per year

Soil is nutrient rich

3-4 tree species per square kilometer (include such species as oak, hickory, beech, hemlock, maple, basswood, cottonwood, elm, and willow)

Has both small and large mammals including squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, and black bear

Located in eastern North America, northeastern Asia, and western and central Europe

Have winter and other seasons

Temperature varies from -22°F to 86°F

Rainfall occurs throughout the year, averages 30 to 60 inches per year

Soil is nutrient rich

3-4 tree species per square kilometer (include such species as oak, hickory, beech, hemlock, maple, basswood, cottonwood, elm, and willow)

Has both small and large mammals including squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, and black bear

Types of temperate forests:Types of temperate forests:

Moist Conifer: (trees that produce cones) and evergreen forests: wet winters and dry

summers

Dry conifer forests: low precipitation and located in high elevations

Mediterranean forests: precipitation mostly in winter, less than 40 inches per year.

Temperate coniferous: mild winters, more than 78 inches of rain per year

Temperate broad-leaved rainforests: mild, frost-free winters, and more than 60 inches of rain that occurs throughout the year.

Moist Conifer: (trees that produce cones) and evergreen forests: wet winters and dry

summers

Dry conifer forests: low precipitation and located in high elevations

Mediterranean forests: precipitation mostly in winter, less than 40 inches per year.

Temperate coniferous: mild winters, more than 78 inches of rain per year

Temperate broad-leaved rainforests: mild, frost-free winters, and more than 60 inches of rain that occurs throughout the year.

Boreal forest (also called taiga)Boreal forest (also called taiga)

The largest type of biome (zone) that occurs on land.

Located in Eurasia and North America (66% of boreal forests are in Siberia with the remaining located in Alaska, Scandinavia and Canada)

Have short, moist summers and long, cold dry winters

Most of the precipitation is snow (15 to 40 inches per year)

Has mostly evergreen conifers with needle leaves (pine, fir and spruce trees)

Large and small mammals and birds (hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats)

The largest type of biome (zone) that occurs on land.

Located in Eurasia and North America (66% of boreal forests are in Siberia with the remaining located in Alaska, Scandinavia and Canada)

Have short, moist summers and long, cold dry winters

Most of the precipitation is snow (15 to 40 inches per year)

Has mostly evergreen conifers with needle leaves (pine, fir and spruce trees)

Large and small mammals and birds (hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, chipmunks, shrews, and bats)

Types of boreal forests:Types of boreal forests:

  North American:  2.4 million square

miles that extends from central Alaska in the west to central Labrador in the east.

Eurasian :  3.4 million square miles stretching from western Scandinavia across Northern Europe and Asia to the Pacific Ocean.

  North American:  2.4 million square

miles that extends from central Alaska in the west to central Labrador in the east.

Eurasian :  3.4 million square miles stretching from western Scandinavia across Northern Europe and Asia to the Pacific Ocean.

The different components of a forest ecosystem

Abiotic component : These are the inorganic as well as organic substances present in the soil and

atmosphere.

Biotic component : The living organisms present in the food chain occur in the following order.

Producers : The trees are of different kinds depending upon the kind of the forest formation developing in that climate. Besides trees, there are also present several climbers, epiphytes, shrubs and a ground vegetation.

In tropical moist deciduous forest the producers, are Tectona grandis, Butea frondosa, Shorea rubusta and Anogeissus latifolia, Adina cordifolia and so on.

In temperate deciduous forests the dominant trees are species of Quercus, Acer, Betula ,and conifers such as Abies, Pinus Thuja, Picea etc., whereas in a temperate coniferous forests, the dominant producer trees are gymnosperrns genera : Abies, Picea, Pinus, Cedrus, Juniperus and wide range of flowering plants.

The different components of a forest ecosystem

Abiotic component : These are the inorganic as well as organic substances present in the soil and

atmosphere.

Biotic component : The living organisms present in the food chain occur in the following order.

Producers : The trees are of different kinds depending upon the kind of the forest formation developing in that climate. Besides trees, there are also present several climbers, epiphytes, shrubs and a ground vegetation.

In tropical moist deciduous forest the producers, are Tectona grandis, Butea frondosa, Shorea rubusta and Anogeissus latifolia, Adina cordifolia and so on.

In temperate deciduous forests the dominant trees are species of Quercus, Acer, Betula ,and conifers such as Abies, Pinus Thuja, Picea etc., whereas in a temperate coniferous forests, the dominant producer trees are gymnosperrns genera : Abies, Picea, Pinus, Cedrus, Juniperus and wide range of flowering plants.

Consumers

(a) Primary consumers. These are the herbivores that include the animals feeding on tree leaves as ants, flies, beetles, leafhoppers, bugs and spiders etc., and larger animals grazing in shoots and/or fruits of the producers, the elephants, nilgai, deer, moles, squirrels, shrews, flying foxes, fruit bats, mongooses etc.,

(b) Secondary consumers. These are the top carnivores like snakes, birds, lizards, fox etc. feeding on the herbivores.

(c) Tertiary consumers. These are the top carnivores like lion, tiger, etc., that eat carnivores of secondary consumers level.

Consumers

(a) Primary consumers. These are the herbivores that include the animals feeding on tree leaves as ants, flies, beetles, leafhoppers, bugs and spiders etc., and larger animals grazing in shoots and/or fruits of the producers, the elephants, nilgai, deer, moles, squirrels, shrews, flying foxes, fruit bats, mongooses etc.,

(b) Secondary consumers. These are the top carnivores like snakes, birds, lizards, fox etc. feeding on the herbivores.

(c) Tertiary consumers. These are the top carnivores like lion, tiger, etc., that eat carnivores of secondary consumers level.

Decomposers These are wide variety of microorganisms

including fungi (species of Aspergillus, Coprinus, Polyporus, Ganoderma, Fusarium, Alternariq, Trichoderma etc.), bacteria (species of Bacillus, Clostridhim, Pseudomonas, Angiococcus etc.,) and actinomycetes, like species of Streptomyces etc.

Rate of decomposition in tropical and subtropical forests is more rapid than that in the temperature ones. They actively participate in biogeochemical nutrient recycling.

Decomposers These are wide variety of microorganisms

including fungi (species of Aspergillus, Coprinus, Polyporus, Ganoderma, Fusarium, Alternariq, Trichoderma etc.), bacteria (species of Bacillus, Clostridhim, Pseudomonas, Angiococcus etc.,) and actinomycetes, like species of Streptomyces etc.

Rate of decomposition in tropical and subtropical forests is more rapid than that in the temperature ones. They actively participate in biogeochemical nutrient recycling.

GRASSLAND ECOSYSTEMSGRASSLAND ECOSYSTEMS Grasslands are dominated by grass

species but sometimes also allow the growth of a few trees and shrubs.

Rainfall is average but erratic.

Seasonal cycles of temperature and precipitation contribute to abundant vegetative growth that both protects and enriches the soils of these prairies and plains, making them among the richest farmlands in the world

Grasslands are dominated by grass species but sometimes also allow the growth of a few trees and shrubs.

Rainfall is average but erratic.

Seasonal cycles of temperature and precipitation contribute to abundant vegetative growth that both protects and enriches the soils of these prairies and plains, making them among the richest farmlands in the world

Three types of grasslands are found to occur in different climatic regions:

(a) Tropical grasslands (25-100cm of annual precipitation)

(b) Temperate grasslands (150 cm of annual precipitaiton)

(c)Polar grasslands (Arctic Tundra)

Three types of grasslands are found to occur in different climatic regions:

(a) Tropical grasslands (25-100cm of annual precipitation)

(b) Temperate grasslands (150 cm of annual precipitaiton)

(c)Polar grasslands (Arctic Tundra)

(a) Tropical grasslands: They occur near the borders of tropical rain forests in regions of high average temperature and low to moderate rainfall. In Africa, these are typically known as Savannas, which have tall grasses with scattered shrubs and stunted trees.

The Savannas have a wide diversity of animals including zebras, giraffes, gazelle, antelopes etc. During dry season, fires are quite common.

Termite mounds are very common here. The termites gather the detritus (dead organic matter) containing a lot of cellulose and build up a mound. On the top of the mound fungi are found to grow which feed upon this dead matter including cellulose and in turn release methane, a greenhouse gas.

Tropical savannas have a highly efficient system of photosynthesis. Most of the carbon assimilated by them in the form of carbohydrates is in the perennating bulbs, rhizomes, runners etc. which are present underground. Deliberate burning of these grasslands can release huge quantities of carbon dioxide, another green house gas, responsible for global warming.

(a) Tropical grasslands: They occur near the borders of tropical rain forests in regions of high average temperature and low to moderate rainfall. In Africa, these are typically known as Savannas, which have tall grasses with scattered shrubs and stunted trees.

The Savannas have a wide diversity of animals including zebras, giraffes, gazelle, antelopes etc. During dry season, fires are quite common.

Termite mounds are very common here. The termites gather the detritus (dead organic matter) containing a lot of cellulose and build up a mound. On the top of the mound fungi are found to grow which feed upon this dead matter including cellulose and in turn release methane, a greenhouse gas.

Tropical savannas have a highly efficient system of photosynthesis. Most of the carbon assimilated by them in the form of carbohydrates is in the perennating bulbs, rhizomes, runners etc. which are present underground. Deliberate burning of these grasslands can release huge quantities of carbon dioxide, another green house gas, responsible for global warming.

Rhizome

Termite mound

Savannas are grasslands with scattered trees

Savannas are grasslands with scattered trees

(b) Temperate grasslands: They are usually found on flat, gentle sloped hills, winters are very cold but summers are hot and dry. Intense grazing and summer fires do not allow shrubs or trees to grow.

In United States and Canada these grasslands are known as prairies, in South America as Pampas, in Africa as Velds and in central Europe and Asia they are known as Steppes.

Winds keep blowing and evaporation rate is very high. It also favours rapid fires in summer. The soils are quite fertile and therefore, very often these grasslands are cleared for agriculture.

(b) Temperate grasslands: They are usually found on flat, gentle sloped hills, winters are very cold but summers are hot and dry. Intense grazing and summer fires do not allow shrubs or trees to grow.

In United States and Canada these grasslands are known as prairies, in South America as Pampas, in Africa as Velds and in central Europe and Asia they are known as Steppes.

Winds keep blowing and evaporation rate is very high. It also favours rapid fires in summer. The soils are quite fertile and therefore, very often these grasslands are cleared for agriculture.

Temperate grasslands include the North American prairie

Temperate grasslands include the North American prairie

Most abundant in Steppes –antelope

veld veld

Steppes - bustard

(c)Polar grasslands (Arctic Tundra): They are found in arctic polar region where severe cold and strong, frigid winds along with ice and snow create too harsh a climate for trees to grow.

In summers the sun-shines almost round the clock and hence several small annual plants grow in the summer.

The animals include arctic wolf, weasel, arctic fox, reindeer etc.

A thick layer of ice remains frozen under the soil surface throughout the year and is known as permafrost. In summer, the tundra shows the appearance of shallow lakes, bogs etc. where mosquitoes, different type of insects and migratory birds appear

(c)Polar grasslands (Arctic Tundra): They are found in arctic polar region where severe cold and strong, frigid winds along with ice and snow create too harsh a climate for trees to grow.

In summers the sun-shines almost round the clock and hence several small annual plants grow in the summer.

The animals include arctic wolf, weasel, arctic fox, reindeer etc.

A thick layer of ice remains frozen under the soil surface throughout the year and is known as permafrost. In summer, the tundra shows the appearance of shallow lakes, bogs etc. where mosquitoes, different type of insects and migratory birds appear

Long, bitter-cold winters characterize the tundra

Long, bitter-cold winters characterize the tundra

Arctic wolf Reindeer

weaselGrass

DESERT ECOSYSTEMSDESERT ECOSYSTEMS These ecosystems occur in regions where

evaporation exceeds precipitation (rainfall, snow etc.)

The precipitation is less than 25 cm per year. About l/3rd of our world's land area is covered by deserts.

Deserts have little species diversity and consist of drought resistant or drought avoiding plants.

The atmosphere is very dry and hence it is a poor insulator. That is why in deserts the soil gets cooled up quickly, making the nights cool. Deserts are of three major types, based on climatic conditions:

These ecosystems occur in regions where evaporation exceeds precipitation (rainfall, snow etc.)

The precipitation is less than 25 cm per year. About l/3rd of our world's land area is covered by deserts.

Deserts have little species diversity and consist of drought resistant or drought avoiding plants.

The atmosphere is very dry and hence it is a poor insulator. That is why in deserts the soil gets cooled up quickly, making the nights cool. Deserts are of three major types, based on climatic conditions:

(a) Tropical deserts like Sahara and Namib in Africa and Thar desert, Rajasthan, India are the driest of all with only a few species. Wind blown sand are very common.

(b) Temperate deserts like Mojave in Southern California where day time temperatures are very hot in summer but cool in winters.

(c) Cold deserts like the Gobi desert in China has cold winters and warm summers.

(a) Tropical deserts like Sahara and Namib in Africa and Thar desert, Rajasthan, India are the driest of all with only a few species. Wind blown sand are very common.

(b) Temperate deserts like Mojave in Southern California where day time temperatures are very hot in summer but cool in winters.

(c) Cold deserts like the Gobi desert in China has cold winters and warm summers.

Temperate DesertsTemperate Deserts

Cold DesertCold Desert

Gobi Desert

Deserts are defined by their drynessDeserts are defined by their dryness

Tropical DesertTropical Desert

Thar desert Sahara desert

Desert Ecosystem : Structure and Function:

Deserts occupy about 17 per cent of land, occurring in the regions with an annual rainfall of less than 25 centimeters. The various biotic components are :

1.Producers. stems and branches variously modified, a few succulents like cacti are present. Some lower plants like lichens and xerophytes mosses may be present.

2. Consumers The most common animals are reptiles and insects, able to live under xeric conditions. In additions to them, there are also found some nocturnal rodents and birds. The 'ship of desert', camels feed on tender shoots of the plants.

3. Decomposers. These are very few, as due to poor vegetation the amount of dead organic matter is

correspondingly less. They are some fungi and bacteria, most of which are

thermophilic.

Desert Ecosystem : Structure and Function:

Deserts occupy about 17 per cent of land, occurring in the regions with an annual rainfall of less than 25 centimeters. The various biotic components are :

1.Producers. stems and branches variously modified, a few succulents like cacti are present. Some lower plants like lichens and xerophytes mosses may be present.

2. Consumers The most common animals are reptiles and insects, able to live under xeric conditions. In additions to them, there are also found some nocturnal rodents and birds. The 'ship of desert', camels feed on tender shoots of the plants.

3. Decomposers. These are very few, as due to poor vegetation the amount of dead organic matter is

correspondingly less. They are some fungi and bacteria, most of which are

thermophilic.

succulent plant or succulent is a plant that has fleshy and turgid water-storing tissues such as stems, leaves or roots, capable of retaining large amounts of moisture 

succulent plant or succulent is a plant that has fleshy and turgid water-storing tissues such as stems, leaves or roots, capable of retaining large amounts of moisture 

ProducersProducers

ConsumersConsumers

consumersconsumers

AQUATIC ECOSYSTEMSAQUATIC ECOSYSTEMS Aquatic ecosystems dealing with water bodies

and the biotic communities present in them are either freshwater or marine.

Freshwater ecosystems are further another type

(lentic) -like ponds, lakes or free-flowing type (lotic)-like rivers.

Freshwater ecosystems are varied because they are influenced not only by

local climate, soil, but also by the surrounding terrestrial

ecosystems.

Aquatic ecosystems dealing with water bodies and the biotic communities present in them are either freshwater or marine.

Freshwater ecosystems are further another type

(lentic) -like ponds, lakes or free-flowing type (lotic)-like rivers.

Freshwater ecosystems are varied because they are influenced not only by

local climate, soil, but also by the surrounding terrestrial

ecosystems.

Lentic Ecosystem - PondsLentic Ecosystem - Ponds

Lotic Ecosystem - LakesLotic Ecosystem - Lakes

Pond ecosystemPond ecosystem

It is a small freshwater aquatic ecosystem where water is stagnant.

Ponds may be seasonal in nature i.e. receiving enough water during rainy season.

Ponds are usually shallow water bodies

They contain several types of algae, aquatic plants, insects, fishes and birds.

It is a small freshwater aquatic ecosystem where water is stagnant.

Ponds may be seasonal in nature i.e. receiving enough water during rainy season.

Ponds are usually shallow water bodies

They contain several types of algae, aquatic plants, insects, fishes and birds.

Pond ecosystemPond ecosystem

Structure and Function: A pond is a good example of a small

self-sufficient and self-regulating ecosystem.

Location, size ,depth and substratum of a pond influence pond ecosystem.

Fresh waters, are extremely important as a source of drinking water.

Structure and Function: A pond is a good example of a small

self-sufficient and self-regulating ecosystem.

Location, size ,depth and substratum of a pond influence pond ecosystem.

Fresh waters, are extremely important as a source of drinking water.

Biotic component: The various organisms that constitute the

biotic component are as follows :

1. Producers : (a) Macrophytes : They are mainly large rooted

plants which include partly or completely submerged, floating

The common plant species are Trapa, Typha, Sagittaria, Nymphara, Potamogeton, Chara, Hydrilla, Vallisheria, Utricularia, Marselia, Eicchornia, Spirodella, Lemna etc also occur in the pond.

Biotic component: The various organisms that constitute the

biotic component are as follows :

1. Producers : (a) Macrophytes : They are mainly large rooted

plants which include partly or completely submerged, floating

The common plant species are Trapa, Typha, Sagittaria, Nymphara, Potamogeton, Chara, Hydrilla, Vallisheria, Utricularia, Marselia, Eicchornia, Spirodella, Lemna etc also occur in the pond.

Macrophytes

MacrophytesMacrophytes

(b) Phytoplankton (b) Phytoplankton These are minute, floating or

suspended lower plants.

Majority of them are filamentous algae such as Ulothrix, Spirogyra, Cladophora and Oedogonium.

Besides them there are also present Volvox, Microcystis, Oscillatoria, Chlamydomonas, Spirulina

These are minute, floating or suspended lower plants.

Majority of them are filamentous algae such as Ulothrix, Spirogyra, Cladophora and Oedogonium.

Besides them there are also present Volvox, Microcystis, Oscillatoria, Chlamydomonas, Spirulina

PhytoplanktonsPhytoplanktons

2.Consumers :Most of the consumers are

herbivores while a few insects and some large fish are carnivores.

The consumers in a pond ecosystem are distinguished as follows :

2.Consumers :Most of the consumers are

herbivores while a few insects and some large fish are carnivores.

The consumers in a pond ecosystem are distinguished as follows :

(a) Primary consumers : These are herbivores feeding directly on living plants (producers) or plant remains. They may be large as well as minute in size.

Benthic populations include fish, insect larvae, beetles, mites, molluscs, crustaceans etc.

Besides these, some mammals as cows, buffaloes etc., visit the pond casually and feed on marginal rooted macrophytes. Some birds also regularly visit the pond feeding on some hydrophytes.

(ii) Zooplankton : These are chiefly the rotifers as Brachionus, Asplancha Lecane etc, some protozoans as Euglena, Coleps, Dileptus etc

(a) Primary consumers : These are herbivores feeding directly on living plants (producers) or plant remains. They may be large as well as minute in size.

Benthic populations include fish, insect larvae, beetles, mites, molluscs, crustaceans etc.

Besides these, some mammals as cows, buffaloes etc., visit the pond casually and feed on marginal rooted macrophytes. Some birds also regularly visit the pond feeding on some hydrophytes.

(ii) Zooplankton : These are chiefly the rotifers as Brachionus, Asplancha Lecane etc, some protozoans as Euglena, Coleps, Dileptus etc

ZooplanktonsZooplanktons

(b) Secondary consumers (Carnivores) : They are the carnivores, which feed on the primary consumers herbivores. These are chiefly insects and fish, which feed

on zooplankton.

(c) Tertiary consumers (carnivores) : Some large fish feed on the smaller fish and thus become the tertiary (top) consumers.

In a pond, fish may occupy more than one trophic levels. The small fish (herbivores) feed

on phytoplankton while some fish feed on zooplankton at carnivore level.

(b) Secondary consumers (Carnivores) : They are the carnivores, which feed on the primary consumers herbivores. These are chiefly insects and fish, which feed

on zooplankton.

(c) Tertiary consumers (carnivores) : Some large fish feed on the smaller fish and thus become the tertiary (top) consumers.

In a pond, fish may occupy more than one trophic levels. The small fish (herbivores) feed

on phytoplankton while some fish feed on zooplankton at carnivore level.

3.MicroConsumers or Decomposers : They are also known as micro consumers,

since they absorb only a fraction of the decomposed organic matter.

They bring about the decomposition of

complex dead organic matter of both plants and animals to simple forms.

3.MicroConsumers or Decomposers : They are also known as micro consumers,

since they absorb only a fraction of the decomposed organic matter.

They bring about the decomposition of

complex dead organic matter of both plants and animals to simple forms.

Lake ecosystemsLake ecosystems

Lakes are usually big freshwater bodies with standing water.

They have a shallow water zone called Littoral zone, an open-water zone where effective penetration of solar light takes place, called Limnetic zone and a deep bottom area where light penetration is negligible, known as profundal zone

Lakes are usually big freshwater bodies with standing water.

They have a shallow water zone called Littoral zone, an open-water zone where effective penetration of solar light takes place, called Limnetic zone and a deep bottom area where light penetration is negligible, known as profundal zone

Stratification of lakesStratification of lakes The lakes show stratification or zonation based on

temperature differences.

During summer, the top waters become warmer than the bottom waters. Therefore, only the warm top layer circulates without mixing with the colder layer, thus forming a distinct zonation:

Epilimnion : Warm, lighter, circulating surface layer

Hypolimnion : Cold, viscous, non-circulating bottom layer.

In between the two layers is thermocline, the region of sharp drop in temperature.

The lakes show stratification or zonation based on temperature differences.

During summer, the top waters become warmer than the bottom waters. Therefore, only the warm top layer circulates without mixing with the colder layer, thus forming a distinct zonation:

Epilimnion : Warm, lighter, circulating surface layer

Hypolimnion : Cold, viscous, non-circulating bottom layer.

In between the two layers is thermocline, the region of sharp drop in temperature.

Stratification of lakesStratification of lakes

Rivers and Streams EcosystemsRivers and Streams Ecosystems

As compared with lentic freshwaters (ponds, lakes etc), lotic waters such as streams and rivers have been less studied.

Producers : The chief producers that remain permanently attached to a firm substrate are green algae such as Cladophora, encrusting diatoms and aquatic mosses.

As compared with lentic freshwaters (ponds, lakes etc), lotic waters such as streams and rivers have been less studied.

Producers : The chief producers that remain permanently attached to a firm substrate are green algae such as Cladophora, encrusting diatoms and aquatic mosses.

Green algaeGreen algae

Types of Green algaeTypes of Green algae

Phytoplanktons-Diatoms & MossesPhytoplanktons-Diatoms & Mosses

Consumers :The consumers show certain such features as permanent attachment to firm substrate, presence of hooks and suckers, sticky undersurfaces.

Thus a variety of animals are found, which are

freshwater sponges and caddisfly larvae, larvae of Stimulium , snails and flatworms, fish and stonefly

Decomposers : Various bacteria and fungi like actinomycetes are present which acts as decomposers.

Consumers :The consumers show certain such features as permanent attachment to firm substrate, presence of hooks and suckers, sticky undersurfaces.

Thus a variety of animals are found, which are

freshwater sponges and caddisfly larvae, larvae of Stimulium , snails and flatworms, fish and stonefly

Decomposers : Various bacteria and fungi like actinomycetes are present which acts as decomposers.

ConsumersConsumers

spongesmayfly flatworms

snails

EstuariesEstuaries An estuary is a partially enclosed coastal area

at the mouth of a river where fresh water and salty seawater meet.

Constant mixing of water stirs up the silt which makes the nutrients available for the primary producers.

There are wide variations in the stream flow and tidal currents at any given location diurnally, monthly and seasonally.

An estuary is a partially enclosed coastal area at the mouth of a river where fresh water and salty seawater meet.

Constant mixing of water stirs up the silt which makes the nutrients available for the primary producers.

There are wide variations in the stream flow and tidal currents at any given location diurnally, monthly and seasonally.

Therefore, the organisms present in estuaries show a wide range of tolerance to temperature and salinity.

Such organisms are known as eurythermal and euryhaline. Coastal bays, and tidal marshes are examples of estuaries.

Therefore, the organisms present in estuaries show a wide range of tolerance to temperature and salinity.

Such organisms are known as eurythermal and euryhaline. Coastal bays, and tidal marshes are examples of estuaries.

Estuaries have a rich biodiversity and many of the species are endemic.

There are many migratory species of fishes like eels and salmons in which half of the life is spent in fresh water and half in salty water.

Estuaries have a rich biodiversity and many of the species are endemic.

There are many migratory species of fishes like eels and salmons in which half of the life is spent in fresh water and half in salty water.

SalmonsEels -Anguilla australis

For them estuaries are ideal places for resting during migration, where they also get abundant food.

Estuaries are highly productive ecosystems.

For them estuaries are ideal places for resting during migration, where they also get abundant food.

Estuaries are highly productive ecosystems.

ProducersProducers

Microscopic algae comprising phytoplankton suspended in the water column and benthic diatoms on the sediment

Seaweeds near the mouth of permanently open estuaries

Beds of submerged aquatic plants like eelgrass, generally only exposed at the lowest spring tides, in the middle reaches

Saltmarshes, as well as mangroves in the subtropical and tropical areas of the east coast, in the intertidal zone of the middle and upper reaches

Reeds and aquatic grasses at the head of the estuary.

Microscopic algae comprising phytoplankton suspended in the water column and benthic diatoms on the sediment

Seaweeds near the mouth of permanently open estuaries

Beds of submerged aquatic plants like eelgrass, generally only exposed at the lowest spring tides, in the middle reaches

Saltmarshes, as well as mangroves in the subtropical and tropical areas of the east coast, in the intertidal zone of the middle and upper reaches

Reeds and aquatic grasses at the head of the estuary.

ProducersProducers

seahorse

Redknobbed coot

Herons