The document explains that the sun is the primary energy source for ecosystems, with plants converting solar energy into chemical energy through photosynthesis. Energy flows in one direction through trophic levels, where approximately 90% is lost at each level, following the 10% law proposed by Lindeman and supported by Odom. It also discusses the food chain and food webs, highlighting the interconnection of various organisms within these systems.

1. ENERGY FLOW
IN ECOSYSTEM
ENVIRONMENT AND ECOLOGY

2. What is the source of energy
for almost all ecosystems ?
o The Sun supports earth’s ecosystem.
• Plants create chemical energy from abiotic
factors that include solar energy which is known
as photosynthesis.
• Chemical energy produced is stored in plants
tissues, a part of this energy is used by the
plants for photosynthesis activities and the rest
is transferred to next trophic level.
 The food energy created by producers is passed
to consumers, scavengers, and decomposers.

3. Laws of Thermodynamics
There are two laws of thermodynamics are as follows:
First law of Thermodynamics : Energy can neither be
created nor be destroyed but it can change only it’s
form .e.g
The solar energy is converted into chemical energy of
carbohydrates.
Second law of thermodynamics : When energy is being
transform some of the energy is converted into an
unusable form and can not be passed on.
• It occurs at each trophic level, 90% energy is lost &
10% is transferred form one trophic level to another.

4. Trophic Level
• Energy flows through an ecosystem in only one
direction. Energy is passed from organisms at one
trophic level to organisms in the next trophic level.(
solar radiations producers primary consumer
secondary consumer tertiary consumer )
• Most of the energy at a trophic level- about 90% is
used at that trophic level. Organisms need it for
growth, locomotion, heating themselves, and
reproduction.
• At each transfer about 90% energy is dissipated as
heat and never returns to the ecosystem and only
10% of the total energy is available to next trophic
level. This rule of energy flow is known as 10% law.
The concept of 10% law was given by Lindeman and
supported by Odom.

5. Food Chain
The set of organisms that
pass energy from one
trophic level to the next is
called food chain.(In
simple language, all
organisms eat at one
trophic level.)
The various trophic level are as
follows :
 Producers
 Primary consumers
 Secondary consumer
 Tertiary consumer
 Decomposer

6. Food Web
• A food web recognizes that
many organisms eat at multiple
trophic levels. All organisms
depend on two global food webs.
• Food webs are interconnected.
How are these two webs
interconnected? Birds or bears
that live on land may eat fish,
which connects the two food
webs.
• Humans are an important part
of both of these food webs; we
are at the top of a food web,
since no one eats us that means
that we are top predators.

7. THANK YOU