d26c2module 3 more notes

7/30/2019 d26c2module 3 More Notes

1/33

ECOSYSTEMS


2/33

ECOSYSTEMSEcology is the study of the distribution and abundance oforganisms, and the flows of energy and materials between

abiotic and biotic components of ecosystems.

Ecosystem: Defined area with a recognizable landscape formsuch as a forest, grassland, desert, wetland, or coastal area.

ORA living community of Plants and animals in any area togetherwith the non living components of the environment constitutean ecosystem.The nature of ecosystems is based on its geographical featuressuch as mountains, hills etc.

Two broad categories:

- Terrestrial or land based Ecosystem

- Aquatic Ecosystems


3/33

Ecosystems:Fundamental Characteristics

Some ecosystems are fairly ROBUST i.e. less affectedby certain level of human intervention. E.g. Desert

Others are FRAGILE. E.g. Island, Mountains.

Natural Ecosystem: forests, grasslands, deserts

Man-made Ecosystems: Agricultural land, urban orindustrial land use.

ECOSYSTEM DEGRADATION

Ecosystems are being frequently disturbed by varioushuman activities, leading to extinction of keystone

speciesThe reason for depletion of natural resources is two-

fold:

-Population Explosion

-Growth of affluent societies.


4/33

Resource Utilization:

Inequality in resource utilization.

Rich people in affluent societies usegreater amounts of forest products.

Building large irrigation projects has leadto wealth in areas with canals butpopulation dependent on river water found

it difficult to survive. Need for equitable distribution of all types

of natural resources.


5/33

Structure and functions of an

ecosystem. STRUCTURAL ASPECT:

Components that make up structural aspects:

-Inorganic compounds (C, N, H2O)

-Organic compounds

-Climatic regimes

-Producers- Phagotrophs.-Macro Consumers - i.e. large animals

-Micro Consumers-Saprotrophs i.e. absorbers like fungi.

FUNCTIONAL ASPECTS

-Energy Cycles.

-Food Chains.-Diversity- Interlinks between organisms

-Nutrient Cycles -Biogeochemical cycles

-Evolution.


6/33

Producers, Consumers,

Decomposers.

Plants are producers.

Herbivorous animals are Primary Consumers

Carnivorous animals or secondary consumers

live on the herbivores.

Decomposers or detrivores break down dead

(complex) organic material into simpler forms,

which are used by plants as nutrition. Endemic Species.


7/33

Energy flow in Ecosystem

Ecosystem has several interrelated

mechanism that affect human life. These

are:

Water cycle.

Carbon Cycle.

Oxygen Cycle. Nitrogen Cycle.

Energy Cycle.


8/33

Water cycle


9/33

Carbon Cycle


10/33

Nitrogen Cycle


11/33

Oxygen Cycle


12/33


13/33

Food chain

Food chains arerepresentations ofthe predator-prey relationshipsbetween species withinan ecosystem or habitat.

Many chain and web modelscan be applicable dependingon habitator environmental factors. Everyknown food chain has a basemade of autotrophs

Energy must pass from oneliving organism to another.


14/33

Food Web

In an ecosystem there

are very large number

of interlinked chains;

together they form asfood webs.

If the links between

these chains is

disturbed it may leadto loss of species.


15/33

Ecological Pyramids

TROPHIC LEVELS

o First: Green Plants, theProducers

o Second: Herbivore

Animals, the PrimaryConsumers

o Third: Carnivore Animals,The SecondaryConsumers

o Fourth: The Micro-Organisms , TertiaryConsumers


16/33

TYPES OF ECOSYSTEM

1. Natural Ecosystem: These operate themselves undernatural conditions without any major interference byman. These are of two types:

a). Terrestrial Ecosystem-

- Forest ecosystem.- Grassland ecosystem.

- Desert ecosystem.

- Mountain ecosystem.

- Island ecosystem.

b). Acquatic ecosystem-

- Fresh water ecosystem pond, lake, river, streams.

- Marine water ecosystem sea, ocean etc.

2. Artificial Ecosystem : Maintained artificially by man

eg. croplands- maize, rice-fields, wheat etc.


17/33

FOREST ECOSYSTEMS

A forest ecosystem has 2 parts:

- The Non Living or ABIOTIC aspects

Type of forest depends on the abiotic components. Theforests on mountains differ from those found by the river

plains. Vegetation is specific to amount of rainfall andtemperature.

- Living or the biotic aspects

Plants and animals form communities that are specific to

each forest type. E.g. coniferous trees are found inHimalyas. Forests in western ghats and north east Indiahave the richest diversity of plant and animal species.


18/33

Forest types in India

Himalyan Coniferous forest.

Himalyan broad leaved.

Evergreen North East, Western Ghats,Andaman and Nicobar.

Deciduous Dry.

Deciduous Moist.

Thorn and scrub Semi arid Forests.

Mangrove Delta Forests.


19/33

Forest Utilization

Over-exploitation of fuel-wood and timber and Conversion tomonoculture for timber impoverishes the local people andeconomically benefits people who live elsewhere.

They play an important role in controlling local climate and waterregimes.

Forest products like fruit, roots, herbs, fodder, medicinal plants,NTFPs (non timber forest products) such as fiber, cane and gum areused for household purposes.

These products are collected, sold and marketed, hence are of greateconomic importance.

Branches and leaves are burnt to form wood ash which acts asfertilizer for crops such as rice.

Wild relatives of our crop plants are used to develop newer varieties.These give greater yields and are more resistant to diseases.

Forests are being lost due to mining and building dams.


20/33

Grassland ecosystem

Grasslands cover areas where rainfall is usually lowand/or the soil quality is poor.

But the conditions are sufficient to support the growth ofgrass during monsoons.

During summers, the grass and herbs become dry andpart above the ground dies.

The grass cover grows back from the root stock and theseeds of the previous year.

This gives the grasslands a seasonal appearance. The animals in this region have adapted to conditions

here where food is plentiful after the rains, which isstored as fat to be used during dry periods.


21/33

Certain grassland types are formed when

clearings are made in different forest types.

The grasslands are related to repeated forestfires that do not permit the forest to grow

The grasses are major producers of biomass in

this regions.

Some grasses and herbs are more sensitive to

overgrazing and are suppressed when the area

is overgrazed.

Frequently burnt or overgrazed grasslands aredegraded and poor in biodiversity.


22/33

Types of Grasslands in India

1. Himalayan Pasture Belt -It extends upto thesnowline. Himalayan wildlife requires both theforest and grassland ecosystem. The animalsmigrate to the grasslands during summer andmove to forest in winters. They have largevariety of grasses and herbs along with anumber of medicinal plants.

2. Terai- The patches of tall elephant grass growsto a height of 5 mts are located in low lying waterlogged areas. It includes marshes in low lyingdepressions.


23/33

3. Semi arid plains of Western& CentralIndia Deccan.

Covered by grasslands with patches of thornforest. Several mammals such as BlackBuck, Chinkara etc are adapted to these

arid conditions. The Deccan is coveredwith seasonal grasses and herbs.

4. Shola Grasslands- These formpatchworks of grasslands on the slopes

and forest habitats along atreams and lowlying areas. E.g. Western ghats,

Annamalai ranges, Nilgiri.


24/33

Uses of grasslands

Grazing areas for rural communities.

Fodder is collected and stored to feed cattle.

Grass is used to thatch houses and farm sheds.

Thorny bushes and branches are sources offuelwood.

Grasslands have diverse insect species thathelp in pollination of crops.

The predators of these insects (frogs, lizard,shrews) help to control pests in adjoiningagricultural lands.


25/33

Desert Ecosystem The deserts and semi arid areas are mainly located in the western

India and the Deccan Plateau.

The climate is extremely dry. There are certain cold deserts also

such as in Ladakh. These regions have highly specialized insects and reptiles. Animals

include Indian wolf, Desert Cat, Desert fox etc.

THAR DESERT

- Has sand dunes.

- Covered with sparse grasses and shrubs

- Rainfall is scanty and sporadic.

- Vegetation consists majorly of thorny trees and a few shrubs.

RANN OF KUTCH

- Low lying areas near the sea

- They get converted to salt marshes during the monsoons.

- They attract a number of aquatic birds such as ducks, geese,cranes.

- It is the only known breeding colony of the Greater and LesserFlamingos.


26/33

Uses of Desert and semi Arid

ecosystem

Areas Of scanty vegetation- Camel Cattle

and goat grazing in Rajasthan and Gujrat.

Areas with Little moisture- Used for

growing crops such as Jowar and Bajra.

Natural grasses and local varieties of

crops have adapted to grow at low

moisture levels. These can be used for

genetic engineering.


27/33

Threats to desert Ecosystems Development strategies and Human

population Growth. Conversion of this land through extensive

irrigation system has changed naturalcharacteristics of this region.

The region is prone to salinity resulting inpoor productivity.

Over Extraction from ground water from

tube-wells lowers the water table, creatingan even drier environment.

Conservation Of Desert Ecosystem


28/33

Conservation Of Desert Ecosystem

Desert people have traditionally protected

their meager water resources. E.g. the

Bishnoi tribehas protected theirkhejdi

treesand blackbuck antelopefor

generations.

Development projects alter the desert and

arid landscape. E.g. The Indira Gandhi

canal in Rajasthan is destroying this

natural arid ecosystem as it will convertthe region into intensive agriculture.


29/33

Aquatic Ecosystem These comprise of marine environments of the seas and freshwater

systems. Act as a wealth of natural resources

-Food (Fish and Crustaceans)

-Break down the chemical and organic waste created by man. (Thisfunction has a limitation. Beyond a certain limit this waste causespollution, which cannot be handled by this ecosystem.

Misuse and overutilization. Over Fishing

Change in river course due to construction of dams.

Wetlands drainage cause floods in connected rivers.

Physical Aspects Clarity

Salinity

Oxygen Content

Rate of flow


30/33

Classification

1) On the basis of velocity of Water:

Running Water Ecosystems

Stagnant Ecosystems2)Based on Salinity:

Freshwater (Low Salinity)

Brackish (Medium Salinity) Marine Ecosystems. (High Salinity)


31/33

Pond Ecosystem

Most ponds become dry after the monsoon season is over and arecovered with terrestrial plants for the rest year.

When a pond fills up during the rain its life forms come out of thefloor where they remained dormant during the dry phase.

Gradually more complex animals such as frogs, crabs and fishreturn to the pond.

The vegetation consists of floating weeds and rooted vegetation.

When a pond fills a large number of food chains are formed.

Algae Microscopic Animals Small Fish Carnivorous Fish Birds

Aquatic Insects Waste Materials excreted Detritus


32/33

Lake Ecosystems It functions like a giant permanent pond.

The food chains are similar to pond ecosystem.

A large amount of plant material is comprised by

the algae which derives its energy from the sun.

Some specialized fish such as the catfish feedson the detritus on the muddy bed of the lake.

They are called Bottom Feeders

Plants use CO2 for their growth and release

Oxygen, which is used by Aquatic Animals,

which filter water through their respiratory

system.


33/33

Marine Ecosystem

The Indian Ocean, Bay of Bengal and Arabian Seaconstitute the marine ecosystem in peninsular India.

They can be contrasted with freshwater ecosystems,which have a lower salt content.

Marine life is a vast resource, providing food, medicine,and raw materials, in addition to helping tosupport recreation and tourism all over the world. At afundamental level, marine life helps determine the verynature of our planet. Marine organisms contribute

significantly to the oxygen cycle, and are involved in theregulation of the Earth's climate

d26c2module 3 more notes

Documents