Ecosystems and the
Biosphere
Ecology Unit
Newark Academy Summer Session 2014
Advanced Credit Biology
Monkemeier

All organisms need
energy to carry out
essential functions such
as growth, movement,
maintenance, repair
and reproduction.

In an ecosystem,
energy flows from the
sun to autotrophs ,
then to organisms that
eat the autotrophs,
then to organisms that
feed on other
organisms.
The sun is the ultimate source of
energy for all life on Earth.



Organisms that capture the sun’s energy and
transform it into chemical energy contained
within organic compounds are known as
autotrophs.
Some bacteria undergo chemosynthesis to
manufacture their own organic compounds.
Chemosynthesis is a process that
manufactures organic molecules using energy
from inorganic molecules.
Organisms that manufacture organic
compounds using either photosynthesis or
chemosynthesis are known as PRODUCERS.
Producers
Terrestrial Ecosystems

Plants are major
producers
Producers
Aquatic Ecosystems

Photosynthetic
protists and bacteria
are major producers
Gross Primary Productivity
Gross primary productivity is the rate at
which energy is produced (by producers
mainly through photosynthesis) in an
ecosystem.
 In other words: Gross primary
productivity is the rate at which producers
in an ecosystem capture the sun’s energy
and transform it into chemical energy
contained within sugars.

Gross Primary Productivity
Plants metabolize some of their
manufactured sugars during cellular
respiration.
 Plants also utilize some of their
manufactured sugars to grow, repair and
reproduce.
 The sugars made by PRODUCERS
increases the BIOMASS in the ecosystem.

Sugars made by Photosynthesis
Biomass is all of the ORGANIC MATERIAL
in an ecosystem. It includes the bodies of
plants, animals, etc.
 ONLY energy stored as biomass is
available to other organisms in the
ecosystem.
 Ecologists measure the productivity of an
ecosystem by measuring the rate at which
BIOMASS accumulates in a specific
ecosystem.

Biomass
The rate at which biomass accumulates
within an ecosystem is known as NET
PRIMARY PRODUCTIVITY.
 NPP is typically expressed in units of
energy per unit area per year. (kcal/m2/y)


NPP = GPP – Rate of respiration of
producers
NET PRIMARY PRODUCTIVITY
Comparative Productivity of
Ecosystems
 Heterotrophs:
all heterotrophs rely
upon ingestion or absorption of
organic compounds made by other
organisms (ultimately made by
producers)
 Heterotrophs = Consumers
 Herbivores, carnivores, omnivores
are all forms of Consumers.
Consumers

DETRITIVORES are
consumers that
feed on the
“wastes” of an
ecosystem such as
dead bodies of
organisms, fallen
vegetation and
wastes of animals.

DECOMPOSERS
cause decay by
breaking down the
complex molecules
in dead tissues and
wastes into simpler
molecules.
Consumers that RECYCLE
Energy Flow
Energy Pyramids
Energy Transfers within an
ecosystem