Ecological pyamids

1. AAAA BriefBriefBriefBrief NoteNoteNoteNote onononon EcologicalEcologicalEcologicalEcological PyramidsPyramidsPyramidsPyramids ofofofof EcosystemEcosystemEcosystemEcosystem
An ecological pyramid is a sort of graphical representation showing the
relationship between the various tropic levels of a community. In food web energy
flow is often represented by a diagram of quantitative relationship among various
tropic levels.
Large amounts of energy and biomass are dissipated at every tropic level, .with
each level retaining a much smaller amount than the proceeding level, and
diagrams looks like a triangular pyramids. These are 03333 types of ecological
pyramids.
(i)(i)(i)(i) PyramidsPyramidsPyramidsPyramids ofofofof Numbers:Numbers:Numbers:Numbers:
In most of the food chains, the number of organism's decreases in each tropic level,
a large number of small animals occur at the base, a few large ones at the top.
The pyramid may be upright or inverted depending upon the size of producers in
the community.
The base of the pyramid always represents the numbers of primary producers and
the subsequent structure on the base are represented by the number of consumers
of successive levels, the top representing the number of top carnivores in the
ecosystem e.g. Ponds ecosystem.

2. (ii)(ii)(ii)(ii) PyramidPyramidPyramidPyramid ofofofof Biomass:Biomass:Biomass:Biomass:
Biomass means total dry weight of dry matter or caloric value present in the
ecosystem at any one time. The pyramid of biomass means weight of organisms at
different tropic level e.g. terrestrial, pond ecosystem.
Most biomass pyramids narrow sharply from the producer level at the base to the
top-level consumers at the peak. There are some exceptions, however. In certain
aquatic ecosystems, the zooplankton (primary consumers) consume the
phytoplankton (producers) extremely rapidly. As a result, the zooplankton have a
greater mass at any given time than the phytoplankton. The phytoplankton grow
and reproduce at such a rapid rate that they can support a consumer population that
has a greater biomass. A biomass pyramid for this ecosystem would appear top
heavy.
(iii)(iii)(iii)(iii) PyramidPyramidPyramidPyramid ofofofof energy:energy:energy:energy:
The total amount of energy utilized by different tropic level organisms of an
ecosystem in unit area over a set period of time.

3. The pyramid of energy depicts the amount of energy flow to each successive tropic
level in community. Greater amount of energy is available at the producer level
then the consumer level.
In general, an average of only 10 percent of the available energy at a trophic level
is converted to biomass in the next higher trophic level. The rest of the
energy—about 90 percent—is lost from the ecosystem as heat.
Energy pyramids are always slopping because less energy is transferred from each
level than was paid into it. Energy pyramid indicates amount of energy flow at
each level and also actual role the various organisms play in the transfer of energy.
Productivity:Productivity:Productivity:Productivity: The relationship between the amount of energy accumulated and the
amount of energy utilized within one tropic level of food chain clarify how much
energy one tropic level passes to next tropic level.
ProductivityProductivityProductivityProductivity ofofofof EcosystemsEcosystemsEcosystemsEcosystems:::: What determines an ecosystem's energy budget? For
most ecosystems, the answer begins with the amount of sunlight that enters the
ecosystem. Much of the sunlight that bombards Earth every day bounces back into
space or is absorbed by the atmosphere. Of the light energy that reaches plants and
other producers, only a tiny fraction—about 1 percent—is captured by
photosynthesis. The producers convert this light energy to the chemical energy
stored in organic compounds. Even such a small percentage of the sun's total
energy output is enough to enable Earth's producers to manufacture billions of
kilograms of organic material, or biomass, each year. The rate at which producers
in an ecosystem build biomass is called primary productivity. The level of primary
productivity in an ecosystem sets the energy budget. In other words, primary
productivity determines the maximum amount of energy available to all the higher
trophic levels in an ecosystem. (Net productivity refers to the total amount of
organic material produced minus the amount used by the producers themselves to
fuel their own life processes.) Notice that the productivity of the tropical rain
forest is considerably higher than that of the temperate grassland, which is higher
than that of the tundra. The rain forest's climate —warm and humid—and

4. year-round growing season allow for high productivity. In contrast, producers in
the typically cold and dry tundra grow more slowly and contribute less biomass
than those in the rain forest. Conditions for producers in the grasslands fall in
between, and so does their productivity.
The ratio of output of energy to input of energy is referred to as ecologicalecologicalecologicalecological
efficiency.efficiency.efficiency.efficiency. Different kinds of efficiencies can be measured by the following
parameters (a) Ingestion (b) Assimilation (c) Respiration.
The portion of fixed energy a tropic level passes on to the next tropic level is
called production. Green plants fix solar energy and accumulate it in organic forms
as chemical energy. Since it is first and basic form of energy storage, the rate at
which the energy accumulates in the green plants or producers is known as
primary productivity.
The amount of organic matter present at a given time per unit area is called
standing crop or biomass. The amount of energy based organic matter created per
unit area and time is left after respiration of these plants is net primary production
(NPP) or plant growth.