5. types of ecosystems

8/2/2019 5. Types of Ecosystems

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Ecos stem

Terrestrial A uatic Wet lands

Grass land Fresh Water Marine

eser a e cean

on


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FOREST ECOSYSTEM

The ecosystems having a predominance of trees

Large number of species of herbs, shrubs, climbers, lichens, algae and

wide variety of wild animals and birds

Present in undisturbed areas receiving moderate to high rainfall and

usua y occur as s a e c max commun es.

Depending upon the climatic conditions forests can be of various types:

a. Tropical Rain Forests d. Temperate rain forests

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c. Tropical scrub forests

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f. Evergreen coniferous forests


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They are evergreen broadleaf forests , Found near the equator.

Tropical Rain Forests

High temperature, high humidity and high rainfall

Richest in biodiversity

Presence of different types and layers of plants and animals

The Emergent layer is the topmost layer of the tallest broad-leaf

evergreen trees

Canopy where top branches of shorter trees form an umbrella like cover

Below this is present the Understory of still smaller trees

Contain woody climbers, Orchids (epiphytes )


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The understore trees usuall receive ver dim sunli ht.

They develop dark green leaves with high chlorophyll content

The shrub layer receives even less sunlight

Ground layer known as forest floor receives almost no sunlight

Termites, fungi, mushrooms etc. grow on the ground layer

Large, Colourful, Fragrant and Attractive flowers

Rafflesia arnoldi, the biggest flower (7 kg weight)

Silent Valle in Kerala is the onl tro ical rain forest l in in India


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Found a little away from the equator

Characterized by a warm climate the year round

Deciduous means "falling off at maturity"

a n occurs on y ur ng monsoon

A large part of the year remains dry

Lose their leaves during dry season.


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Tropical scrub forests

They are found in areas where the dry season is even longer.

Here there are small deciduous trees and shrubs.

Temperate rain forests

.

These are dominated by coniferous trees like pines, firs,

redwoods etc.

The also consist of some ever reen broad-leaf trees.


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Temperate deciduous forests

Found in areas with moderate temperatures.

ere s a mar e seasona y w ong summers, co u no o

severe winter and abundant rainfall throughout the year.

The major trees include broad leaf deciduous trees like oak, hickory,

o lar etc.


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Evergreen coniferous forests

They are found just south of arctic tundra.

Here winters are long, cold and dry.

.

In summer the temperature is mild, sun-shines for long hours but the

.

The major trees include pines, spruce, fir, cedar etc. which have tiny, needle

sha ed leaves havin a wax coatin so that the can withstand severe cold

and drought.

The soil is found to get frozen during winter when few species can

survive.

These soils are acidic and prevent other plants from growing.

Species diversity is rather low in these forests.


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GRASSLAND ECOSYSTEMS

Grasslands are dominated by grass species but sometimes also allow

.

Rainfall is average but random

Limited grazing helps to improve the net primary production

Overgrazing leads to degradation resulting in desertification.

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

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b. Temperate grasslands

c. Polar grasslands


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Tropical grasslands

They occur near the borders of tropical rain forests in regions of

.

In Africa, 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 propagate..

Termite mounds are very common here.


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Tem erate rasslands

They are usually found on flat, gentle sloped hills, winters are

very cold but summers are hot and dry.

In central Europe and Asia they are known as Steppes.

Winds keep blowing and evaporation rate is very high.

It also favors rapid fires in summer.

The soils are quite fertile and therefore, very often these

grass an s are c eare or agr cu ure.


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Polar grasslands (Arctic Tundra)

,

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.


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DESERT ECOSYSTEMS

These ecosystems occur in regions where evaporation exceeds

reci itation rainfall snow etc. .

The precipitation is less than 25 cm per year.

About 1/3rd of our world's land area is covered by deserts.

Deserts have little species diversity and consist of drought resistant or

drought avoiding plants.

.

That is why in deserts the soil gets cooled up quickly, making the

nights cool.


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Deserts are of three major types, based on climatic conditions:

(a) Tropical deserts like Sahara and Namib in Africa, and Thar

desert in India are the driest of all with only a few species.

Wind b own sand dunes are very common.

(b) Temperate deserts like Mojave in Southern California where

day time temperatures are very hot in summer but cool in winters.

and warm summers.


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Desert plants and animals are having most typical adaptations

for conservation of water.

Man desert lants are found to have reduced scal leaves so as to

cut down loss of water due to transpiration or have succulent leaves

to store water.

Many a times their stems get flattened and develop chlorophyll so

that they can take up the function of photosynthesis.

.

Many plants have a waxy, thick cuticle over the leaf to reduce loss

of water through transpiration.


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Aquatic ecosystems dealing with water bodies and the biotic

communities present in them are either freshwater or marine.

Freshwater ecos stems are further of standin t e lentic like

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

Let us consider some important aquatic ecosystems.

(a) Pond ecosystem

(b) Lake ecosystem


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

. .

season.

Ponds are usuall shallow water bodies which la a ver im ortant role

in the villages where most of the activities center around ponds.

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

birds.

The ponds are, however, very often exposed to tremendous

anthropogenic (human-generated) pressures.

They are used for washing clothes, bathing, swimming, cattle cleaning

and drinking etc. and therefore get polluted.


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Lakes are usually big freshwater bodies with standing water.

They have a shallow water zone called Littoral zone.

An o en-water zone where effective enetration of solar li ht takes

place, called Limnetic zone.

Deep bottom area where light penetration is negligible, known as

profundal zone.

The benthic zone is the ecological region at the lowest level of a body

o wa er suc as an ocean or a a e, nc u ng e se men sur ace


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(Uttaranchal) and Loktak lake in Manipur

Organisms :(a) Planktons that float on the surface of waters e.g. phytoplanktons

like algae and zooplanktons like rotifers.

(b) Nektons that swim e.g. fishes.(c) Neustons that rest or swim on the surface.

(d) Benthos that are attached to bottom sediments e.g. snails.

(e) Periphytons that are attached or clinging to other plants or

any other surface e.g. crustaceans.


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Thermal Stratification of Lakes

The lakes show stratification or zonation

based on temperature differences.

During summer, the top waters become

warmer than the bottom waters. Therefore,

mixing with the colder layer, thus forming

Epilimnion : Warm, lighter, circulating

surface la er

Hypolimnion : Cold, viscous, non-

circulating bottom layer.

In between the two layers is Thermocline,

the region of sharp drop in temperature.


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Oceans

Gigantic reservoirs of water covering more than 70% of earth

Play a key role in the survival of about 2,50,000 marine species

Serving as food for humans and other organisms

A huge variety of sea-products and drugs

Provide us iron, phosphorus, magnesium, oil, natural gas, sand and gravel.

Major sinks of carbon dioxide

Play an important role in regulating many biogeochemical cycles

Regulates the earths climate.

e oceans ave two ma or e zones:

Coastal one


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Coastal zone

Relatively warm, nutrient rich shallow water.

Due to high nutrients and ample sunlight this is the zone of

high primary productivity.

Open sea

It is the deeper part of the ocean, away from the continental shelf (The

su merge par o e con nen .

It is vertically divided into three regions:

-

photosynthetic activity.

ii Bath al zone - Receives dim li ht and is usuall eolo icall

active.

(iii) Abyssal zone is the dark zone, 2000 to 5000 meters deep. The

abyssal zone has no primary source of energy i.e. solar energy. It is the

world's largest ecological unit but it is an incomplete ecosystem.


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Estuary

An estuary is a partially enclosed coastal area at the mouth of a river

where fresh water and salty seawater meet.

These are the transition zones which are strongly affected by tidal action.

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

o to erance to temperature an sa n ty.

Such organisms are known as eurythermal and euryhaline.

, .


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s uar es ave a r c o vers y an many o e spec es are en em c.

There are many migratory species of fishes like eels and salmons in which

.

For them estuaries are ideal places for resting during migration, where they

also et abundant food.

Estuaries are highly productive ecosystems.

The river flow and tidal action provide energy subsidies for the estuary

thereby enhancing its productivity.

Estuaries are of much use to human beings due to their high food potential.


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Wetlands

There are four wetland ecosystem types marshes, swamps, fens and

bo s and each of them is different.

Of all the wetland types, the marsh is the most productive.

Marshes are shallow wetlands less than two meters deep.

In different areas of the marsh, different plant communities thrive.

In deep water areas, submergent and floating leaved plants grow.

, .

Marshy areas like this may also develop in the shallow parts of lakes and

streams.


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Submergent plants grow in deeper water, further from shore.

The whole body of these plants grows under the water except when they

flower. Like emergent plants, their roots are anchored in the soil at the bottom

of the marsh.

Pondweeds come in a variety of shapes and sizes.

e see s, eaves an roots o pon wee s are an mportant oo source or

many birds.

Water milfoil has very fine leaves and is especially important as both a

home and a food source for many aquatic invertebrates.


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A common floating leaved plant is duckweed.

it in the water.

It often forms a bright green carpet across broad areas of the marsh.

It is easily pushed around by wind or waves and is important as a home for

many insects and as food for ducks.

Water lilies are rooted in the soil and have showy white or yellow flowers.


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5. types of ecosystems

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