2. CONTENTS
Environment & Ecology
Ecosystem
Types of Organisms
Types of Consumer
Ecological Pyramids
Types of Ecological Pyramids
Number Pyramids
Biomass Pyramids
Energy Pyramids
Limitations of Ecological Pyramids
3. Environment
&
Ecology
The sum total of all surroundings of a living organism, including
natural forces and other living things, which provide conditions for
development and growth, is called the environment.
Ecology is the study of the relationships between plants, animals,
people, and their environment, and the balances between these
relationships.
4. Ecosystem
An ecosystem is defined as a community composed of both living
and non-living entities that altogether live and work together.
Ecosystems have no definite sizes as they can be as small as a tree
or as large as the whole land mass.
Ecosystems are broken into different ranks called trophic levels.
5. Types of
Organisms
Ecosystems are broken into different ranks called trophic levels.
Every organism then is classified based on different environmental
factors like how they live in a certain ecosystem (what they eat
and how they obtain energy).
Organisms that make their own food using the sunlight are
called producers.
The next level in the hierarchy is the consumers that consume the
producers and they are categorized as primary, secondary,
or tertiary.
6. Types of
Consumers
Primary consumers are the ones that feed on the producers.
Secondary consumers are the organisms that consume the
primary consumers.
Tertiary consumers are the ones that consume both primary and
secondary consumers.
7. Ecological
Pyramids
Ecologists have devised certain ways to classify organisms into
trophic levels and one of which is the use of ecological pyramids.
In 1927, the concept of ecological pyramid was first proposed by
English Ecologist named Charles Elton.Thus, they are also known
as Eltonian pyramids.
An ecological pyramid is basically a pyramidal depiction of
the number of organisms, biomass, and productivity in each trophic
level in an ecosystem.
8. Ecological
Pyramid
Typically, ecological pyramids
start with producers located
at the bottom and transcend
through various trophic levels
as you go up the pyramid.
The top of the pyramid
represents the highest level
in the food chain.
9. Why are
ecological
pyramids
shaped like
pyramids?
When the food passed from primary producers to secondary
consumers and then to tertiary consumers (carnivores), it is
estimated that about 10% of energy is lost during the process.
To graphically explain this concept, ecologists came up with the
pyramid diagrams, hence the ‘Ecological Pyramids.’
11. NUMBER
PYRAMID
It graphically represents the population (total number of
individuals) present at each trophic level.
This type of pyramid can have two different forms depending on
the number of organisms:
Upright and inverted.
In an upright pyramid of number, the number of organisms
generally decreases from the bottom to top.This generally occurs
in grassland and pond ecosystems where the plants (usually the
grasses) occupy the base of the pyramid.The succeeding levels of
the pyramid include the consumers.
An inverted pyramid of number, on the other hand, is just the
opposite of the former. It is usually observed in tree ecosystems
with the trees as the producers and the insects as consumers.
13. BIOMASS
PYRAMID
The total quantity or weight of organisms in a given area or volume
is called biomass. It refers to the food available for the succeeding
trophic level.
A pyramid of biomass is a depiction of the amount of food available
and how much energy is being passed on at each trophic level.
The pyramid of biomass can either have two forms:
upright and inverted.
Usually, terrestrial ecosystems are characterized by an upright
pyramid of biomass having a larger base (primary producers) with
the smaller trophic levels (consumers) located at the top.
On the other hand, aquatic ecosystems are the complete opposite
as they will assume the inverted structure of the pyramid.This is
because the phytoplankton producers (with generally smaller
biomass) are located at the base while the consumers having larger
biomass are located at the top of the pyramid.
14.
15. ENERGY
PYRAMIDS
The pyramid of energy shows the overall energy in the ecosystem
and how much energy is required by organisms as it flows up the
higher trophic levels.
The pattern of the energy flow in this type of pyramid is based on
the principles of thermodynamics.This law specifically says that
energy is neither be created nor destroyed; only transformed into
another form.
During the flow of energy from organism to other, there is
considerable loss of energy in the form of heat.The primary
producers like the autotrophs there is more amount of energy
available.The least energy is available in the tertiary consumers.
Thus, shorter food chain has more amount of energy available
even at the highest trophic level.
The energy pyramid always upright and vertical.
16.
17. Limitations of
Ecological
Pyramids
While the three ecological pyramids are highly specific to the
aspect of ecosystem they want to describe, all of them still tend to
overlook important aspects. Some of these limitations are the
following:
These types of pyramids only are applicable in simple food chains
(and not food webs), which do not necessarily occur naturally.
They also do not consider the possible presence of the same
species at different trophic levels.
Moreover, none of the three ecological pyramids provide any idea
related to variations in seasons and climates.
Other organisms like microorganisms and fungi are not given
specific role in the pyramids despite their vital roles in ecosystems.
