This document provides an overview of ecosystems. It defines an ecosystem as any system composed of physical, chemical, and biological processes within a space-time unit of any magnitude. Ecosystems can be divided into biomes characterized by climate, landscape, or vegetation. Biomes contain various habitats and are home to populations, communities, and food webs. Energy flows through ecosystems via food chains and pyramids. The document also discusses different types of ecosystems such as forests, tundra, and rainforests, and how they are structured and function.

1. Gauri Haval
Assistant Professor
Department of Zoology
A.G. College, Pune

2. Ecosystem is the basic functional unit.
• It can be defined as any system composed of physical,
chemical and biological processes within a space time unit of
any magnitude.
•In other words the living organisms and their non living
environment are inseparably interrelated and interact upon
each other. Any unit that includes all the organisms that
function together in a given area interacting with the physical
environment so that flow of energy leads to clearly defined
biotic structures and cycling of material between living and
non living parts is an ecosystem.

3.  The whole earth can be broadly divided into lithosphere,
hydrosphere and atmosphere. To these three ecological
components we can add biosphere.
 Biosphere can be divided into different biomes.
 Biomes are characterized by either landscape, climate or
vegetation. E.g.. Desert, Rain forest, Sea etc.
 Biomes are subdivided into small units called zones.
 Within each biome are various habitats.
 Individuals form the population, populations form the
community, communities will lead to an ecosystem.
Ecosystems will lead to biomes.

4.  The two major aspects of an ecosystem are
structure and function.
 Structure of an ecosystem.
A) Abiotic components B) Biotic components.
Abiotic components are
a) Landscape, soil, climate, air, water, light .
b) Inorganic substances- carbon, nitrogen, oxygen,
phosphorous, sulphur etc.
c) Organic substances- carbohydrates, proteins,
liquids, humus etc.

5.  Biotic components
 An ecosystem has two main biotic components
A) An Autotrophic component : able to fix light energy and
manufacture food from simple organic substances.
B) A heterotrophic component: which utilizes, rearranges,
decomposes the complex materials synthesized by
autotrophs.
These functional components are arranged in
overlapping layers . The greatest Autotrophic
metabolism occurring in the upper green belt where
light energy is available. The most intense
heterotrophic activity taking place in the lower brown
belt where organic matter accumulates in the
soil and sediments.

6.  It is convenient to recognize four
constituents comprising ecosystem
1. Abiotic components- basic elements,
climate, landscape etc.
2. Producers- Autotrophic organisms mainly
green plants.
3. The large consumers – Heterotrophic
organisms mainly animals
4. Decomposers- micro consumers- chiefly
bacteria and fungi.

7. One of the universal feature of all ecosystems,
whether terrestrial or aquatic or human
engineered is the interaction of the
Autotrophic and heterotrophic components.
However, to run any system energy is
required.

9.  The number and diversity of organisms and rate
at which they live depends not only on
geographical position, evolutionary process,
magnitude of energy but on the flow of energy
through biological systems.
 It is also dependent on the rate of circulation,
exchange of nitrogen, carbon, water and other
minerals between living and non living things.
 Energy once used is converted into heat. Then it
no longer power life processes. It is lost from the
ecosystem.
 All living organisms & machines are alike, they
are kept going by the continuous inflow of
energy from outside.

10.  One way flow of energy is an universal
phenomenon.The laws of thermodynamics say
that energy is neither created nor destroyed and
energy may be transformed from one type to
another.
 The second law of thermodynamics states that
no process involving an energy transformation
will occur unless there is a degradation of energy
from a concentrated form into dispersed form.
Some energy is always dispersed into
unavailable heat energy. This law is also called
entropy law

11.  Organisms and ecosystems maintain their
highly organized, low entropy state by
transferring energy from high to low utility
states.
 If the quantity or quality of energy flow
through a forest or a city is reduced, then the
forest or city literally begins to degrade.
 To explain this--

12.  Sun – 5000,000 k.cal/m2/year
 Atmosphere –1000,000 k.cal/m2/year
 Ecosystem– 500,000 k.cal/m2/year
 Leaves ---2000 k.cal/m2/year
 Rabbit --- 200 k.cal
 Carnivore – 40 k. cal

13.  It is important to note that useful work is
accomplished at each transfer.
 We can not eat much of it or use it directly to run
our machines, all of incoming solar radiation is
vital to the operation of biosphere. It warms the
biosphere of life tolerable levels.
 It powers weather systems, drives hydrological
cycles.
 A little bit decrease in heat brings on an ice age
while small increase brings tropical era with a
melting of all polar ice raising the sea level.

15.  The transfer of food energy from the source
in plants through a series of organisms with
repeated stages of eating and being eaten is
known as Food chain.
 Green plants occupy the first trophic level-
Producers.
 Plant eaters – Herbivores – second level-
Primary consumer level.
 Carnivores that eat herbivores- Third level-
Secondary consumers.
 Fourth Level – Tertiary consumers.

16.  These trophic levels are not species wise. A given
species population may occupy one or more trophic
levels.
 If an average 1500k cal of light energy absorbed by
green plants/m2/day
 Net plant production 15 k cal.
1.5 k cal – Primary consumer.
0.3 k.cal– Secondary consumer.

17.  Meat is generally higher nutritional quality. However,
energy is lost in each transfer. The amount of food
remaining after 2-3 successive transfer is very small. Only
few organisms could be supported.
 The shorter the food chain or nearer the organism to the
beginning of food chain, greater is the available food
energy.
 100 acres of corn –10 times more people can be
supported if they are primary consumers. If corn –
animals – eat meat i.e. secondary consumers – the
population must be low.
 Tiger is at the top of food chain- the number is less
than primary consumers.

18. Sun - solar energy
Primary consumers
Producers
dead remains Primary carnivore
Secondary carnivore
raw material
Decomposers

19.  Food chains
 Organisms of an ecosystem are linked
together.
 Sheep may eat grass and in turn may be eaten
by a man.
 Grains Mouse Owl, hawk, fox
 Algae zooplankton crustacean
fish bird, frog snake.
 There are many examples of food chains.
 All these food chains involve several links.

20.  Food chains are not isolated from each other.
A mouse in the field may eat several types of
seeds and be preyed upon by several
carnivores. Each carnivore may consume
more than one type of prey.
 The food chains interlock with one another.
 This interconnecting network of species is
called as food web.

22.  In the successive steps of grazing food chain,
the number and mass of the organisms in
each step is limited by the amount of energy
available.
 Since some energy is lost as heat, in each
transformation the steps become
progressively smaller near the top.
 This relationship is sometimes called
Ecological pyramid. It represents the trophic
structure and function of the ecosystem.

23.  In many ecological pyramids, the producer
forms the base and the successive trophic
levels make up the apex.
fish
Carnivore
Carnivore worms
herbivore zooplankton
producers phytoplankton

25.  Energy based classification of ecosystems.
1. Unsubsidized natural, solar powered ecosystems:
a) Depend on direct rays of sun.
b) They are unsubsidized in the sense that there is little
auxiliary source of energy to supplement solar energy.
examples- open seas, large grasslands, upland forests,
large deep lakes.
c) These are subjected to limitations – shortage of
nutrients or water. They are low productive
d) Organisms that populate such systems have evolved
remarkable adaptations for living and efficiently using
energy source.

26. 2. Naturally subsidized solar powered
ecosystem
Example : Coastal estuary, Rain forest.
 Naturally subsidized by the energy of tides, waves &
currents. Back and forth flow of water does the work of
recycling mineral nutrients and transporting food and
wastes.
 The organisms in an estuary concentrate their efforts on
more efficient conversion of sun energy on organic
matter. Organisms are adapted to use tidal power.
 Estuaries tend to be more fertile. Productivity is more.

27. 3. Man subsidized solar powered ecosystem:
Example- Agriculture & aquaculture
Man has learned to modify and subsidize nature for his
benefit. He has become increasingly skillful in not only
raising productivity but more especially in channeling
that productivity into food and fiber.
High yields of food are maintained by large inputs of fuel
involved in cultivation, irrigation, fertilization, genetic
selection and pest control.
Thus tractor fuel as well as animal /human labor is just as
much as energy input as sunlight.
The processing and transportation of food also needs
energy inputs. Thus food we eat also has part of oil in it.

28.  Man subsidized urban industrial ecosystem
 Here sun energy is replaced by highly concentrated
potential energy of fuel. Solar energy is unused in the
cities. However, solar energy becomes a costly nuisance
by heating up the concrete, contributing to the
generation of fog.
 Food which is the product of solar energy is considered
as an externality. The food is imported from outside.
Cities are densely populated. An energy requirement is
enormous. Waste is assimilated, not recycled. If recycles
only in small portions. Water is also not recycled.

29.  The cities create pressure on surrounding areas. These
areas are low powered sun systems.
 The richer the city in its power use , greater the area of
life support that is required.
 It is no accident that all of the world’s great industrial
cities are located on coasts, large estuaries, rivers or
fertile deltas. In these areas life support capacity of the
natural environment is very high or extensive.
 The food and fiber comes from the surrounding area, the
waste is assimilated in the cities. Recycling will not take
place. Creating more and more pressure in terms of
mineral loss, in surrounding areas.

30.  Ecosystems are of two types
 A) Aquatic B) Terrestrial
Terrestrial Ecosystems:
Only about a quarter of the earth’s surface is dry land. Yet
the complexity and variegation of terrestrial ecosystems
are much greater than those of aquatic ecosystems.
Variety of climates, diversity of lithosphere and
heterogeneity of terrestrial biotic communities all
conspire to give variety of themes.
Terrestrial ecosystem is a three phase system, where
characteristic of habitat are a function of atmosphere,
climate, soil and biotic community itself.

31.  The earth surface- the continental land mass have been
classified into following regions :
1. Biogeographic realms 2. Biomes.
Biogeographic realms or regions:
Describes distribution of plants and animals over the earth.
There are six major biogeographical regions namely
Palaeartic realm, Nearctic realm, Neotropical realm,
Ethiopian realm, Oriental and Australian realm etc.
Each is characterized by presence of unique organisms.
Biomes : Within these realms and established by a complex
interaction of climate, other physical factors and biotic
factors are large community units are called biomes.

33.  Tundra biome: Marshy plain
 Fragile ecosystem
 Characterized by absence of trees. Presence of dwarf
plants
 Upper ground surface is wet. It remains frozen which
thaw during brief summer. Warmest months averaging
below 10 C.
 The thin carpet of Tundra vegetation includes grasses
and sedges. Low flowering herbs, lichens. The lichen
here is called as reindeer moss.
 Animals : Caribou and Reindeer, arctic hare, fox, polar
bear wolves, snowy owls etc.

34.  High altitude or the Alpine Biome.
 The region of mountain above timber line contains a distinct
flora and fauna and referred as alpine zone. E.g. in
Himalayas.
 A low air density, low oxygen and carbon dioxide, high
ozone, greater penetration of light, cold snow cover, high
wind velocity.
 There are meadow zone and shrub zone.
 Animal life: Many invertebrates are predatory and occur in
lakes and streams. Fishes and amphibians are totally lacking.
A large number of insects and arachnids remain best
adapted. Among vertebrates- snow partridge, snow leopard,
yak, Tibetan sheep, Persian wild goat. etc

35.  Forest Biomes:
 This biomes include a complex assemblage of different kinds
of biotic communities. Optimum conditions of temperature
and moisture responsible for growth of trees.
 There are different types of forests. The classification of
Indian forest was first done by H.G. Champion. The
classification is based on single important factor rain fall.
Annual rain fall (inches) Forest type.
80 and more Evergreen or rain forest
80 to 40 Moist deciduous
40 to 20 Dry deciduous
20 and less Scrub, thorn, dry
deciduous

36.  Along with this there are intermediate
conditions. Such as semi evergreen.
 There are special forests such as Mangrove
forest near coastal region. This is evergreen type
of forest. However, it is not associated with
rainfall but grow where water is in plenty.

39.  Cold regions with high rain fall.
 Strongly seasonal climates with long winters and
small summers.
 The region is commonly called Taiga.
 Characterized by evergreen plant species such as
spruce, pine, fir.
 The animals inhabiting these areas are snow
shoe hare, lynx, wolf, bears, red fox, porcupines,
squirrels, amphibians like Hyla and Rana.

41.  Characterized by moderate climate and broad
leaved deciduous trees which shed their leaves in
fall. The trees are bare over winter and grow new
foliage during spring.
 Present in North America, Europe, Eastern Asia,
part of Australia and Japan.
 Cold winter. Annual rainfall- 75-100 cm.
Temperature-10-20 C. soil is fairly deep.
 Trees are tall. Maple, beech, oak, basswood,
chestnut, willow.
 The understory of shrubs and herbs is well
developed.

42.  Animals : Deer, bears, foxes, squirrels,
bobcats, wild turkey, wood peckers.
 Common invertebrates are earthworms,
millipedes, centipedes, snails, insects.
 Amphibians such as newts, toads,
salamanders, frogs and reptiles such as
snakes, turtles, lizards etc.
 Mammals such as opossum, pigs, mountain
lion, raccoon etc.
 The animals and plants show seasonality.

44.  Occur near equator in central and south
America, Central and western Africa,
Southeast Asia (Parts of India & Malaysia).
 Among the most diverse communities on
earth.
 Temperature and humidity high and
constant.
 Annual rainfall exceeds 200-225 cm.
Generally evenly distributed throughout the
year.

45.  The flora is highly diversified. A square mile may
contain 300 different species of trees.
 Extreme dense vegetation of tropical rain forests
remains vertically stratified with tall trees often
covered with vines, creepers, lianas, orchids.
 The trees form large canopy. The understory of
trees with shrubs, herbs like palms, ferns. Nearly
all plants are evergreen. The leaves are
moderate size, leathery and dark green.

46.  Invertebrate density and abundance very high.
Worms, snails, millipedes, centipedes, scorpions,
spiders, insects, planarians, leeches etc.
 Common vertebrates – arboreal amphibians,
aquatic reptiles, chameleons, geckoes, snakes,
many species of birds and a variety of mammals.
 Mammals such as leopards, jungle cats, ant-eaters,
giant flying squirrels, monkeys and sloth bear. In
the foot hills of forest zone we have tiger, elephant,
samber deer, gaur, chital, swamp deer etc.

48.  Occur in the region whose total rainfall is high but
segregated into pronounced wet and dry periods.
 Found in Southeast Asia, Central and south
America, Northern Australia, western Africa and
tropical islands of the pacific as well as India.
 These forests are commonly known as Monsoon
forests.
 Trees may reach heights over 40 m.but commonly
are 20-30m.
 Stratification is relatively simple with single
understory tree layer.

49.  Canopy is deciduous and understory is
evergreen.
 Teak is often a major tree. Bamboo is also an
important climax shrub.

51.  Savannas are tropical grasslands with scattered
drought resistant trees.
 The height of the trees do not exceed above 10
m. and do not form canopy.
 Savanna is intermediate between forest and
grassland.
 Found in Eastern Africa, Australia, south
America.
 Eastern Africa supports the richest diversity of
grazing mammals.

52.  The trees of savanna are resistant to
desiccation- may be deciduous or evergreen.
Leaves are hard, drought resistant.
 Grasses are most conspicuous and may reach
height 1-2 m.
 Animals found are giraffes, elephants, buffalo,
lions.
 Insect fauna is very rich.-grasshoppers and
termites are predominant.

54.  Rainfall is about 25-75 cm per year not enough
to support a forest yet more than desert.
 Include tall grass prairies, short grass prairies.
 Arid grasslands of North America as well as
steppes of Eurasia, Pampas of South America.
 These are open land communities with limited
moisture. There is movement of air. Provide
natural Pasture for grazing animals.

55.  Dominant plant – grass- buffalo grass.
 Soil- rich, fertile, accumulation of organic
matter.
 Animals – Herbivore- Bison, wild horse,
antelopes, zebra.
 Carnivores- fox, owl, rattle snake, badgers
 Most herbivores aggregate into herds or
colonies which provides protection.
 Characteristic birds are larks, rodent hawks.
 Insects- Termites, locusts, bees,wasps etc.

56.  Similar to this biome we get, scrub forests.
The temperature is high. Rain fall scanty. Less
moisture.

62.  Formed in driest environments.
 Temperatures may range from very hot as in hot
deserts to very cold in cold deserts.
 Hot deserts- Sahara-Arabia-Gobi, Rajasthan.
 Cold deserts- Ladakh, Tibet, Bolivia arctic.
 Hot desert : Rain fall less than 10mm.
 Soil and air temperatures extremely high by day
and drop abruptly by night, low humidity.

63.  Desert plants-shrubs adapted to drought
conditions through reduced leaf size,
dropping of leaves. Roots are well developed.
Ephemerals are common. Cacti, water storing
succulents, euphorbia are common.
 Animals: reptiles, insects, burrowing rodents,
mules, camels. These animals show great
adaptation.

64.  Indian desert shows 4 habitats : Aquatic,
sandy, rocky, riparian.
 In the perennial lakes- Amphibians- toads,
frogs. Fishes.
 Reptiles- crocodiles, lizard, snakes.
 Birds- Partridge, Quail, Indian Bustards.
 In winter numerous aquatic birds.
 Mammals- Bats, squirrel, porcupine, wolf,
jackals, fox, mongoose and cats.

65. What Landscape architect
should do
 To create places that improve rather than
degrade over time
 What is needed?
 Complete inventory of the site
 History of the location, land use pattern.

66.  Reference ecosystem if available
 Data of the site with reference to flora, fauna,
geography, geology, climate, rainfall,
different ecosystems such as grassland,
forest, rocks, soil, seral stages, special
habitats, stream. Kind of landscape, contours
etc.

67. If all mankind were to disappear,
The world would regenerate back to the rich state of
equilibrium
That existed ten thousand years ago.
If insects were to vanish,
The environment would collapse into chaos.
Edward O
Wilson

68. Thank You