This document summarizes key aspects of trophic structure and nutrient cycling within ecosystems. It discusses how energy and matter move through food chains and webs. Producers, consumers, and decomposers are defined. Nutrient cycling is explained, with a focus on the carbon cycle. Carbon is cycled between reservoirs in the atmosphere, biosphere, hydrosphere, and lithosphere. The document provides examples of carbon storage in limestone from shells and skeletons, and fossil fuels.

1. Presented to Dr.Tanveer Ahmad
Presented by M.Bilal Khalil…….

2.  Trophic structure of
ecosystem
 Cycling within
ecosystem

3. Trophic structure of ecosystem

4. Ecosystem
Communities
and their
physical
environment
is called
ecosystem.

5. ü One important fact of ecosystem is that
the energy is being constantly used and
reused in the ecosystem and once it
leaves the ecosystem it never be used
ü Energy supports all the activities of
organisms in the ecosystem
ü It is in the ecosystem in the form of
sunlight and then incorporated in the
chemical bonds of living and decaying
tissues and is lost as heat .

6. Energy
moves in
the
ecosystem
through a
series of
organisms
called
food
chain .

7. Complexly
interconnected
food chains are
called food
webs

8. Producers obtain their food (complex
organic matter ) from simple inorganic
material and an energy source .

9.  These are the organisms which get their
food from others .
 Herbivores (primary consumers) eat
producers eg.grasshopper
 Carnivores (secondry consumer) eat
herbivores eg.frog
 Other carnivores (tertiary consumer)
which eat herbivorous carnivores
eg.snake

10.  These are the organisms which eat on
the large chunks of dead and decaying
organisms .

12.  Decomposers break dead organisms and
feces of organisms by digesting extracellularly
and absorbing the products of the digestion

14.  The efficiency by which the animals of a
trophic level converts food into new
biomass depends upon the nature of
food
 Biomass conversion efficiency averages
10%.
 However efficiencies ranges from less
than 1% for herbivorous endotherms to
35% for carnivorous ectotherms .

16. Q Did you ever wonder where the calcium
atoms in your bones were 100 or even
100 million years ago?
Perhaps they were in the bones of an
ancient reptile or in the sediments of
prehistoric seas unlike energy all matter is
cycled from non living reservoirs to living
systems and then back to non living
reservoirs .

17.  A nutrient is an element essential for life
approx 97% of living matter is made of
O ,C,N and H .
 Gaseous cycle involving these elements use
the atmosphere or oceans as a
reservoir .Elements such as S,Ca,P are less
abundant in living tissues then are those
with gaseous cycle but they are no less
important in sustaining life
 The non living reservoir for these nutrients is
the earth ,and the cycles involving these
elements are called sedimentary cycles .
 Water also cycles through ecosystem its
cycle is called hydrological cycle.

18.  To understand biogeochemical cycle
we discuss the carbon cycle .

19.  The reservoir of carbon is CO2 in the
atmosphere or water
 Carbon enters the reservoir when organic
matter is oxidized to CO2 .CO2 is released
into atmosphere or water where
autotrophes incorporate it into the organic
compounds
 In aquatic system where some of the CO2
combines with water to form carbonic acid
because this reaction is irreversible so it can
supply CO2 to aquatic animals when there
is low level of CO2 .carbonic acid also
supply CO2 to atmosphere.

20.  Some of the carbon in the aquatic
ecosystem is tied up as calcium
carbonate CaCO3 in the shells of molusc
and skeleton of echinoderms .
 Accumulation of shells of mollusks and
skeleton of echinoderms form the
limestone which is bed rock of most of
the united states .Geological uplift,
volcanic activities and weathering return
much of this carbon to earth surface
and the atmosphere

21. Mollusk shell Echinoderm skeleton

22.  Other carbon is tied up in the fossil fuels
which when burnt out give carbon as
CO2.

23.  Miller Harley book of zoology
 WWW,google.com