ECOLOGICAL SCIENCE

1. ~PRESENTED BY
GROUP - 9
⮚ SHIVANAND (13001320013)
⮚ DEEPMITA SAHA (13001320016)
⮚ SUVADEEP DE (13001320032)
⮚ NAVNEET KISHORE (13001320043)
⮚ AVIJIT DANDAPAT (13001320048)
⮚ SACHIN (13001320055)

2. ECOLOGY
Ecology is the
scientific study of the
distribution and
abundance of
organisms and the
interactions between
organisms and their
abiotic environment.
Ecologists try to
understand the inner
workings of natural
Ecosystems.

3. WHAT IS ECOSYSTEM?
An ecosystem is a geographic area where plants, animals and other
organisms as well as weather and landscape, work together to form a
bubble of life.
Ecosystem have two components
❖ Biotic Components ( Living Components )
❖Abiotic Components ( Non-living Components )
Below we gave a small chart about it.

4. TYPES OF ECOSYSTEM
Mainly Ecosystem have two
types.
1. Natural Ecosystem
2. Artificial Ecosystem.
Natural Ecosystem have also two
types. It is also called ‘Biomes’.
1. Terrestrial Biomes
2. Aquatic Biomes
This two have also some
division. It discuss in the picture.

5. MATTER IN AN ECOSYSTEM
The flow of matter in an ecosystem is not like energy flow. Matter enters an ecosystem at any level and leaves at
any level. Matter cycles freely between trophic levels and between the ecosystem and the physical environment
(Figure below).
Nutrients are elements, usually in the form of ions, that are
crucial to the growth of living organisms. Nutrients such as
nitrogen and phosphorous are important for plant cell growth.
Animals use silica and calcium to build shells and skeletons.
Cells need nitrates and phosphates to create proteins and
other biochemicals. From nutrients, organisms make tissues
and complex molecules such as carbohydrates, lipids,
proteins, and nucleic acids.Rocks and minerals break down
to release nutrients. Nutrients can be brought in from other
regions, carried by wind or water. When one organism eats
another organism, it receives all of its nutrients. Nutrients can
also cycle out of an ecosystem. Decomposers play a key role
in making nutrients available to organisms. Decomposers
break down dead organisms into nutrients and carbon
dioxide, which they respire into the air. If dead tissue would
remain as it is, eventually nutrients would run out. Without
decomposers, life on Earth would have died out long ago.

6. ENERGY IN AN ECOSYSTEM
The transfer of the energy in the food chain is
limited; and hence, the number of trophic
levels in the food chain is limited. There is
only 10 per cent of the transfer of energy from
each lower trophic level to the next/higher
trophic level. This law, known as the 10 per
cent energy law, was proposed by Raymond
Lindeman. The primary consumers do not
acquire 100 per cent of the energy transfer
from the plants/producers; some of the
energy of the sun is consumed by the plants
during the process of photosynthesis.

7. COMMUNITY ECOLOGY
A naturally occurring group of different plant and animal populations living in common
environment constitute a biotic community. Assemblage of plant populations in abiotic
community and that of animal population is called animal community.
The study of organisms living together in an interrelated manner in an environment is
termed as community ecology or synecology.
Study of plant communities is known as Phytosociology.

8. What Are The Characteristics Of A
Community?
A community has mainly 6 characteristics:
1. Species Diversity
2. Growth forms and structure
3. Dominance
4. Self-Reliance
5. Relative abundance
6. Trophic structure
The living places of the organisms are 2 types:
I. Habitat
II. Ecological Niche

9. FREQUENCY
Frequency is the number of times an organism
species is present in a certain number of plots
of a quadrat of particular size.
It’s actually expressed as a percentage and
sometimes called as frequency index.
Formula: %frequency of a species
= [No. of plots in which the species
occurs/Total no. of plots examined of]*100
i.e. Suppose a species (Sp.1) is present in 15
plots of a 36 plots quadrat,
the freq. of Sp.1 is = (15/36)*100
= 41.7%

10. LIFE FORMS
LIFE FORM CHARACTERISTICS CLIMATE AREA
Phanerophytes Woody perennials (Trees, shrubs) > 25 cm in height
that have their leaf-producing buds elevated above
ground on stems.
Warm and moist Tropical
Cryptophytes Grasses which have above-ground tissues that DIE
BACK IN WINTER or during prolonged dry periods and
survive unfavorable periods as BUDS buried in the
ground on a BULB or RHIZOME.
Warm and dry Temperate
Therophytes Grasses which have above-ground tissues that DIE
BACK IN WINTER or during prolonged dry periods and
survive unfavorable periods as BUDS buried in the
ground on a BULB or RHIZOME.
Hot or cold and dry Desert climate
Hemicryptophytes Perennial shoots or buds are close to the surface of the
ground, often covered with litter.
Hemicryptophytes Temperate/tundra like
Chamaephytes Buds on persistent shoots near the ground – woody
plants with perennating buds borne close to the ground,
no more than 25 cm above the soil surface, (e.g.
Bilberry and Periwinkle).
Extremely cold Tundra-like

11. BIOLOGICAL SPECTRUM
When species within a community are classified into life forms and each life form is expressed as a
PERCENTAGE, the result is a LIFE FORM SPECTRUM (Biological spectrum) that reflects the plants’
adaptations to the environment, especially climate, and provides provides a standard standard means for
describing describing community community structure structure.The ratio of the life forms of different
species in terms of percentage in any floristic community is called the biological spectrum.Biological
spectrum is also called phytoclimatic spectrum because each life form is related to a particular climate
and the composition of a community in terms of life forms also indicates the climatic condition prevailing
in the area. Therefore, biological spectrum is a direct indicator of the environment that is occupied by the
particular community.
LIFE FORM PERCENTAGE
Phanerophytes 46
Cryptophytes 9
Therophytes 26
Hemicryptophytes 6
Chamaephytes 13

12. FOOD CHAIN & FOOD WEB
❑ FOOD CHAIN:-
A Food chain is a series of events in which one organism eats another and obtains energy. A food
chain shows one possible path along which energy can move through an ecosystem
❑ FOOD WEB:-
A food web is the natural interconnection of food chains and a graphical representation of what-eats-
what in an ecological community

13. ECOLOGICAL PYRAMIDS
The arrangement of biotic components of the food chain according
to their size, metabolic relationship is known as ‘Trophic Structure’.
This is specific to each ecosystem.
This relationship between the various trophic levels of a food chain
(Producers herbivores carnivores) can be shown
diagrammatically by ‘Ecological pyramids’.
Ecological pyramids was first proposed by British Ecologist,
Charles Elton (1927), and can also be called as ‘Eltonian pyramids’.
There are three types of ecological pyramids
1. Pyramids of Numbers
2. Pyramids of Biomass
3. Pyramids of Energy

14. PYRAMIDS OF NUMBERS
It shows the relationship between the producers, herbivores and carnivores in terms of their numbers.
This indicates the number of organisms at every trophic level.
Grassland
Ecosystem
Pond
Ecosystem
Parasitic Food
chain
(Inverted)

15. PYRAMIDS OF BIOMASS
The amount of living material in an organism is called biomass.
Pyramid of biomass shows quantitative relationship existing at various trophic levels.
Forest
Ecosystem
Pond
Ecosystem
(Inverted)

16. PYRAMIDS OF ENERGY
In an ecosystem the pyramid of energy shows the amount of total energy trapped by the organism at
each trophic level in a unit area and time and expressed as kcal/m2/year.
Energy pyramids provide the best picture of overall nature of the ecosystem.
Energy pyramid is always upright in all ecosystems.