project on Ecosystem(EVS)

1By : - GauravKumar
What is an Ecosystem?
An ecosystem includes all of the livingthings (plants,animals and
organisms)in a given area,interactingwith each other, and also with their
non-livingenvironments (weather, earth,sun,soil,climate, atmosphere).
Ecosystems are the foundations ofthe Biosphere and theydetermine the
health of the entire earth system.
In an ecosystem, each organism has its own role to play.
Consider a small puddle at the back of your home. In it,you may find all sorts
of livingthings, from microorganisms to insects and plants.These may depend
on non-livingthings like water, sunlight,turbulence in the puddle,
temperature, atmosphericpressure and even nutrients in the water for life.

2By : - GauravKumar
This very complex, wonderful interaction of living things and their
environment, has been the foundations of energy flow and recycle of
carbon and nitrogen.
Anytime a ‘stranger’ (living thing(s) or external factor such as rise in
temperature) is introduced to an ecosystem, it can be disastrous to that
ecosystem. This is because the new organism (or factor) can distort the
natural balance of the interaction and potentially harm or destroy the
ecosystem.

3By : - GauravKumar
Threats to Ecosystems
Anythingthat attempts to alter the balance of the ecosystem potentially
threatens the health and existence of that ecosystem. Some of these threats
are not overly worrying as they may be naturallyresolved provided the natural
conditions are restored.Other factors can destroyecosystems and render all
or some of its life forms extinct. Here are a few:
1. Habitat Destruction
Economicactivities such as logging, mining,farming and construction
often involveclearing out places with natural vegetativecover. Very often,
tamperingwith one factor of the ecosystem can havea ripple effect on it and
affect many more or all other factors of that ecosystem. For example, clearing
a piece of forest for timber can expose the upper layers of the soil to the sun's
heat,causing erosion and drying.It can cause a lot of animals and insects that
depended on the shade and moisture from the tree to die or migrate to other
places.

4By : - GauravKumar
2. Pollution
Water, land and airpollutionall together playa crucial role in the health
of ecosystems. Pollution maybe natural orhuman caused,but regardless they
potentiallyrelease destructiveagents or chemicals (pollutants)into the
environments oflivingthings.“In a lake, for example, it can create havocon
the ecological balance by stimulatingplant growth and causingthe death of
fish due to suffocation resultingfrom lack of oxygen. The oxygen cycle will
stop,and the polluted water will also affect the animals dependent on the lake
water”.
3. Overharvesting
Fish species,game and special plants all do fall victim from time to time
as a result of over harvestingor humans over dependence on them.
Overharvestingleads to reduction in populations,communitystructures and
distributions,with an overall reduction in recruitment.Lots of fish species are
know to havereached theirmaximum exploitationlevel,and others will soon
be.

5By : - GauravKumar
4. UV Radiation
The sun’s rays playan important role in livingthings.UV rays come in three
main wavelengths:UVA, UVB and UVC, and they havedifferent properties.
UVA has longwavelengths and reaches the earth’s surface all the time. It helps
generate vitamin D for livingthings. UVB and UVC are more destructiveand
can cause DNA and cell damage to plans and animals.Ozone depletionis one
way that exposes living things to UVB and UVC and the harm caused can wipe

6By : - GauravKumar
lots of species, and affect ecosystems members includinghumans.
Preserving Ecosystems
Here are a few ways we can ensure the health and smooth functioning
of ecosystems.
1. Habitat preservation
Economicactivity should be managed and made sustainable.Tree
cuttingfor example must be regulated and best practices enforced.

7By : - GauravKumar
2. Invasive Species
In many of the tragedies that ecosystems have faced with the
introductionofalien species,humans havecaused that.It is crucial that proper
inspection,regulation,research and monitoringsystems are in place to protect
weaker nativespecies in ecosystems,if new species are to be introduced.

8By : - GauravKumar
3. Eutrophication
One big cause of eutrophicationis the runoff of surface chemicals and
fertilizers applied to plants duringfarming.Whiles we need food to survive, it
is important that we encourage organicplantingas against the heavyuse of
chemicals.Sewage also need to be inspected and monitored such that when
the waste water is deposited into water bodies,it is properlyfiltered and
treated to reduce the organic nutrient content.
4. Pollution
Air and land pollution together haveeffects
on water bodies too.Acid rains and chemical runoff
all affect life forms in the water. Oils that are
discharged into water bodies can have a devastating
effect. “In aquaticecosystems,air pollutionacidifies
surface waters, reducingtheir abilityto sustain
nativefish. In estuaries and coastal waters,it
contributes to nutrient over-enrichment,producing

9By : - GauravKumar
algal blooms,foul smells and low oxygen levels. It also causes mercury to
accumulate in aquaticfood webs, threateningthe health of both people and
wild animals”
5. Ozone
Ozone is a secondarypollutant.It is the result of the formation of precursors
nitrogen oxides and Volatile OrganicCompounds (VOC).Biomass burning
produces this.It is known that forest cover act as a net sinkof ozone. It is
therefore important that we preservenatural vegetativecovers on earth and
invest in energy forms that reduce the emissions ofVOCs.

10By : - GauravKumar
Five Basic Needs of Living Things
The Basic Needs Of Living Things : -
Every living organism on earth needs some basicthings to survive.The
amount,way, form or kind of these needs vary from organism to organism.
For example, water is a basic need for survival.The amount ofwater a
frog needs to surviveis not the same as the amount ofwater a desert cactus
plant needs to survive. They all need water, but because they are different
livingorganisms,theirwater needs will be different,even though they both
need water to live.
There are five basic needs that all living things have. They are

 Sunlight :- This is probablythe most important need forall living
organisms,because it is the source of all energy. It also provides heat for
plants and animals
 Water: Water is the medium in which livingcells and tissue work.
Water is also a livingenvironment formany plants and animals
 Air: Air is made up of several gases, but the two most important gases
are Oxygen and Carbon dioxide.Withoutoxygen,animals will die, and
without carbon dioxide, plants cannot survive.
 Food (nutrients): Living things need energy for function.Energy is
needed to grow, reproduce, move, and to work. Thinkof what will
happen ifyou stayed for three days without food…
 A Habitat with the Right Temperature: Too cold or too hot?
Every living organism needs the ideal temperature to surviveeither on
land or in water.
Certain factors in a livingorganism's environment can prevent it
from survivingthere. Those factors are called ‘limitingfactors’.They
include soils,temperature, water, sunlight and physical barriers.Physical
barriers may include landforms and water bodies.Theyoften prevent a
livingorganism from moving to another place when conditionsget bad in
theirregular habitat.

Sunlight:-
The sun is the source of all energy, heat
and light. The amount of sunlight in an area
determines what livingthing can survivethere.
For example, the upper part of the sea or ocean
receives a lot of sunlight.It is therefore warmer
than the ocean floor,which has little orno light
at all.Therefore, living things closer to the
surface are very different from livingthings on
the ocean floors.
Plants: Different plants require different
amounts ofsunlight to survive. For example,
ferns need less light,but dandelions need a lot
of direct sunlight.
All plants use sunlight to make food (sugars) in a
process called photosynthesis.Theystore the
food in theirleaves and the energy flows to other animals that eat the leaves.
When leaves fall,decomposers in the soil,work on it, with the help of
moisture and heat from the sun.
Animals: Sunlight is vital for all animals,even though different animals
need different amounts of sunlight and in different ways. For example:many
mammals and reptiles such as snakes,turtles and lizards come out duringthe
day to bask in the sun to raise theirbodytemperatures and become active. At
the same time, some animals like bats run to hide when the sun comes up to
escape the heat.But they too, need the sun.Do you know why?
Indirectly,many nocturnal animals (night animals)need light too.When
they come out in the night,they feed on living things that got energy from the
sun.Here is another example:Animals at the ocean floors depend on organic
matter (dead plants and organisms)that sinkto the floors from the surface.
Such organic matter contains energy that was first produced by the sun.

The amount ofsunlight that livingthings are exposed to triggers migration
of some birds and also aids flowering and pollination.Without this natural
variety,living things will not function properly.
Water : -
Water is needed in many ways and quantities bylivingthings.Water may be
consumed by livingthings,or may be a habitat forthem.Animals that use
water as theirhabitat orhome are called aquaticanimals.Sometimes,there
are many nutrients orchemical compounds dissolved in water, and the
concentrations often decide which
animals can live them. For example,
some fish like herrings live in salty
sea waters, whiles tilapia and
salmon livein fresh water with very
little or no salt concentrations.
Plants: -
Plants need enough hydration to
carry out photosynthesis.Theyget
the water theyneed from the soil through theirroots.The water in plants
carries nutrients to other parts of the plant.Some plants such as the water lily
need a lot of water, whiles desert cacti can go for months with out water.
Water keeps plant firm and upright (turgid).They go flaccid when they go
without water and soon,theydie.
Some plants such as seaweed and algae absorb carbon dioxide dissolved in
water.
Animals:-

Animals also need water to carry out cell activity. Some animals drinkwater
regularlyto keep hydrated,digest food and build bodyfluids.Some fishes need
salt water and others need fresh water. Many kinds of fish such as clams and
trout get oxygen from water.
Some animals havewater as theirhabitat.Other such as frogs and turtle need
water to lay eggs and reproduce.The anaconda snakes,together with many
reptiles livein water. Fresh water often carries lots of dissolved nutrients that
aquaticorganisms depend on.Without water, theywill not survive.
Air :-
The earth is surrounded byair,a mixture of extremely important gases such as
oxygen, carbon dioxide and nitrogen.These gases provide animals with oxygen
for respiration to occur. It also provides green plants with carbon dioxide for
photosynthesis to happen. It is vital that livingthings respire to get the oxygen
for livingcells to function.Without air,there is no life.
Plants :-
Plants use Carbon Dioxide (together with
sunlight and water)to produce energy and give out
Oxygen as a by-product. This oxygen is what almost all
animals need to survive. They absorb Carbon Dioxide
from the air and discharge Oxygen through very tiny
pores in the leaves.
Air is also important forlivingorganisms in the
soil to surviveand function.Without soil aeration,
decomposers cannot work on organicmatter to

decompose them, as soil moisture alone is not enough for decomposition.
Moving air(wind) is also important forsome plants to pollinate.
Animals :-
Animals includinghumans need oxygen to live. We breathe in oxygen
and breathe out Carbon Dioxide.There are also air pockets in soils and water
that help tiny livingthings survivein water and beneath the soils.For example,
fishes absorb Oxygen from water with theirgills. All animals are adapted with
special organs and parts that help them absorb the oxygen they need from the
air.
Food : -
We need food to grow, right? The food we eat contains the
nutrients that our bodies need to replace worn out cells, stay healthy
and stay strong.It is the same for every living organism. Food comes
in many different forms, and plants and animals have special organs
or parts that absorb the goodies from the food we eat.
Plants : -
Plants use sugars, fats and proteins to grow and stay healthy.They
produce these themselves with the help of sunlight,water and carbon dioxide.
The nutrients produced are stored in the plants and the nutrients are passed
on to other animals that eat these plants.
When living things die and rot in the ground,the nutrients in them end up
in the soil and get dissolved in it. As a result,plants roots are able to absorb

nutrients such as salts,potassium, minerals,starch,phosphates and nitricacids
from soils too.
Animals : -
Animals also need food or nutrients
to survive.They get nutrients from
eatingplants.
Bigger animals eat other smaller animals
for food.Aquaticanimals (such as fish)
eat tinywater insects, worms and
plankton.
In some cases, organisms such as fungi,get theirfood by breakingdown
nutrients in organicmatter (once-livingthings). All these contain some specific
nutrients that the animals need to grow healthy.
Habitat (home) :-
Every living organism needs a home, shelter or
environment that provides the safety,ideal temperature
and basic things it needs to survive.
One important function ofthe organism's home
(habitat orenvironment)is to provide the ideal
temperature in which the organism can thrive.
Humans have a way of helpingthemselves if it gets
too cold or too hot. But this is not so for every living
thing.If it is too cold or too hot,some plants will struggle
to survive.
This is same for animals too.An ideal temperature is very important.
Extreme temperature can wipe out an entire ecosystem.

Temperature is affected by water, air, soil and sunlight.
Temperatures are not the same everywhere on earth.Some places such
as the north and south poles are very cold (–88°C or -126.4°F). Other places,
especiallyin the tropics can get very warm (up to about 50°C or 122°F).
Animals that are adapted to cold temperatures cannot survivein warm
temperatures.
Plants:
Some places are just too cold for plants to survive. These include high
mountain peaks such as those in the mountains ofBritish Columbia.
Animals:
Thinkof the brooktrout — it prefers water temperatures between 4°C or
39.2°F and 20°C or 68°F and will onlylay eggs when the water temperature is
below13°C. Animals like polarbears and penguins are adapted to thriveonly
in extremelycold climates.They will not surviveif they end up in a hot,dry
tropical climate.
Metabolicand enzyme activities in animals require the right temperatures
to happen,otherwise, such processes slow down and affect that living
organism.

Scales of Ecosystems
Ecosystems come in indefinite sizes.It can exist in a small area such as
underneath a rock, a decaying tree trunk,or a pond in yourvillage, or it can
exist in large forms such as an entire rain forest.Technically,the Earth can be
called a huge ecosystem.
A simple tree-trunk ecosystem relationship
 Humidityis an abioticfactor.It provides moisture for the tree trunk to
decay.
Therefore, the tree-trunkis dependingon the right humidityto help it
decay
 The decayingtrunk provides fertile grounds for tinygreen plans to grow.
 Tinygreen plants become food for bugs and insects that livein and
around the decayingtree-trunk.
 Bugs and insects become yummy food for small animals like the frog who
hangs around the tree-trunk.
 And… the frog becomes dinner for the big snake hidingunder the trunk.

So there you go. You will now notice that if one member of the chain is
taken out, the entire relationshipwill be affected. For example:if a fire burns
out the tree-trunk,the insects will starveand die, and the frog will haveno
food,and the snake will have to go somewhere else to look for food.The
ecosystem will be no more.
To make things simple, let us classify ecosystems into
three main scales.
Micro: -
A small scale ecosystem such as a pond,puddle, tree trunk,under a rock
etc.
Messo: -
A medium scale ecosystem such as a forest or a large lake.
Biome:
A very large ecosystem or collection ofecosystems with similarbiotic
and abioticfactors such as an entire Rainforest with millions ofanimals and
trees, with manydifferent water bodies runningthrough them.
They are often separated bygeographical barriers such as deserts,
mountains,oceans,lakes and rivers.As these borders are never rigid,
ecosystems tend to blend into each other.This is why a lake can have many
small ecosystems with their own unique characteristics.Scientists call this
blending“ecotone”
Ecosystems can be put into 2 groups. If the ecosystem exists in a water body,
like an ocean, freshwater or puddle, it is called an aquaticecosystem. Those
that exists outside ofwater bodies are called terrestrial ecosystems.

Levels of organization in an ecosystem
 Individual, Species, Organism: -
An individual is anylivingthingor organism.Individuals do not
breed with individuals from other groups.Animals,unlike plants,tend to
be very definite with this term because some plants can cross-breed with
other fertile plants.
In the diagram above,you will notice that Gill,the goldfish,is
interactingwith its environment,and will onlycrossbreed with other
gold fishes just like her.

 Population:
A group of individuals ofa given species that live in a specific
geographic area at a given time. (example is Gill and his family and
friends and other fishes of Gill’s species)Note that populationsinclude
individuals ofthe same species, but may have different genetic makeup
such as hair/eye/skin colourand size between themselves and other
populations.
 Community:
This includes all the populations in a specific area at a given time. A
communityincludes populations oforganisms of different species.In the
diagram above,note howpopulations ofgold fishes, salmons,crabs and
herrings coexist in a defined location.A great communityusually
includes biodiversity.
 Ecosystem:
As explained in the pages earlier, ecosystems include more than a
communityof livingorganisms (biotic)interactingwith the environment
(abiotic).At this level note howthey depend on other abioticfactors
such as rocks, water, air and temperature.
 Biome:
A biome, in simple terms, is a set of ecosystems sharingsimilar
characteristics with their abioticfactors adapted to theirenvironments.
 Biosphere:
When we consider all the different biomes,each blendinginto the
other, with all humans livingin many different geographic areas,we
form a huge communityof humans,animals and plants,and micro-
organisms in their defined habitats.A biosphere is the sum of all the
ecosystems establishedon planet Earth.It is the living(and decaying)
component ofthe earth system.

The Earth System
Introduction to Earth System :-
Water, trees,animals,winds,rocks and so on, all that is part of the planet
we call Earth.
ATMOSPHERE: Air (made up of many gases)
HYDROSPHERE: Sea, lagoon, ice-sheets and ice-caps,
rainwater, etc
BIOSPHERE: Fish, trees and other life forms
GEOSPHERE: Rocks, mountains, sediments on the sea floor,
etc

Earth is made up of all these things and are grouped into four main areas
called spheres.These spheres are not static, that means they are constantly
changing. For example, the atmosphere does not produce the same weather
everyday. We experience the wind,rain or sunshine differentlyeveryday.
Living things such as animals are also born,whiles older ones die. Deep down
the earth,there is molten magma (melted rock) that can be spewed put in the
form of lava duringvolcaniceruptions.Sometimes,there are seismic
movements in the earth's crust which causes changes on the surface of the
earth.So, you can see that there is always somethinggoingon in all the parts
of the earth. It is a dynamic earth.
 What is a system?
A system is a term used for anycomplex whole, with smaller
connected parts working together. Usually,a change or malfunction of
one part can affect other parts of the system, and also affect the system
itself.
The Earth is a system too.It has four
majorparts all connected and working in
harmonyto make the planet function
properly.These four parts are called Spheres.
They are the Atmosphere, Geosphere,
Biosphere, and Hydrosphere. Some studies
also have the cryosphere (ice and snow) and
anthroposphere (man-madeobjects and
processes),but for this lesson,we shall focus
on the four parts.Each sphere has its own function and it is constantly
changing in a process called Cycles.

 What is a Cycle?
A cycle is somethingthat never stops.It has no beginningand has
no end.An example is the water cycle, where the water goes through a
basic journey:rains fall and end up in rivers, rivers end in the sea,sea
water evaporates and forms rain clouds,and the rains fall again.Other
important cycles include the carbon cycle, rock cycle, and nitrogen cycle.
Hydrosphere
 The Hydrosphere : -
The hydrosphere includes all the water parts on the planet.It
includes water on the surface, sub-surface and water vapourin the
atmosphere.The hydrosphere and the atmosphere are known as the
fluid spheres. These spheres are the liquid and gas components ofthe
earth.
Thinkof all the water in the oceans and seas, includingall the
frozen water and ice (cryosphere). Also thinkof all the lakes,lagoons,
rivers and ponds,as well as water in in the water table beneath the
surface of the earth.They are all part of the hydrosphere and together
they cover more than 70% of the surface of the earth.
The hydrosphere is also in infinite processes every day. The water
cycle is one way to understandhowthe hydrosphere functions and
supports other spheres.

The oceans and water bodies absorb the sun's energy and warm up.
Transpiration bytrees and Evaporation ofsurface water occurs. The water
vaporin the atmosphere condenses (condensation)to form rain clouds and
comes down as rain (precipitation).The rains fall back on land and into water
bodies (run-off)again and they all run back into the ocean for the cycle to
continue.
A complete water cycle takes time. Other spheres are impacted in many
ways duringthe water cycle.

Geosphere
 The Geosphere :-
This sphere includes all the stuff that make up the crust and the
core of the earth. It includes everythingnatural and lifeless that make up
the surface of the earth.
Examples are all the rocks and sand particles from dry land to
those found at the bottom of the oceans.They also include the
mountains,minerals,lava and molten magma from beneath the earth’s
crust.
The geosphere undergoes infinite processes constantlyand that,in
turn,modifies other spheres.One example of the continuous process is
the rock cycle.

In the rock cycle, melted rock from below the earth’s crust is spewed out
through vents on the surface onto the surface of the earth.This is also called
lava.Solidified lava,together with other rock material from earth movements
are weathered and eroded.The eroded particles end up somewhere and build
up. After many years of buildup,pressure from the overlying weight causes the
particles to modifyitselfagain.They are further buried deeper in the crust and
then melted again by intense heat until theyare spewed out to the surface
again.
In this cycle, you will notice that it can take thousands ofyears for the
cycle to complete, but every single day has a role to play.You will also notice
that the cycle does not complete on its own. It is influenced byother factors
such as water, temperature, and wind,which also belongto other spheres.

Biosphere
 The Biosphere
The biosphere is all livingcomponent of the earth (humans,plants,
animals,bacteria,fungi,protists and all microscopicorganisms on land,
in the air and in the oceans). It also includes all organic matter that has
not yet decomposed.This livingpart is hugelydependent on the other
three spheres.
The hydrosphere provides moisture orwater to plants and
animals,the geosphere provides the solid surface on which animals and
plants grow and also provides heat from beneath the earth.

The atmosphere provides the gasses (nitrogen,oxygen and carbon
dioxide)needed bylivingthings.The atmosphere also provides the
screen from the sun’s UV radiation and helps us receivejust enough of
the sun's heat.
It is believed that the biosphere is exclusiveto earth alone.
Scientists believethere are traces of water, rock, and gases on other
planets,but no life has been found yet. Humans are exploringother
planets to see if this idea is correct.
The interaction ofthe biosphere with other spheres can be
explained better bya theoryknown as Ecosystems.

Atmosphere
 The Atmosphere
The atmosphere is the gaseous component abovethe surface of
the earth.This sphere is also a fluid sphere (the other fluid sphere is
hydrosphere).The atmosphere is made up of gases and tiny water
particles.The gases surroundingthe earth are kept in place by the force
of gravity.
The atmosphere is a mixture of gases: Nitrogen (78%) and Oxygen
(21%), make up the most.There is also Argon, Carbon Dioxide and
Aerosols (particles such as dust,pollen,ash,smoke). These gases are
super important to life on earth because plants and animals dependon
them to live.
The atmosphere is sustained byenergy from the sun.When the
sun shines,heat is radiated to the earth’s surface and reflected back into
the atmosphere.The heat also warms the surface of the earth and
causes evaporation,therebysendingmoisture into the atmosphere.
Thunderstorms,hurricanes,lightningand tornadoes are all processes of
the atmosphere.

The atmosphere comes in layers.The troposphere is the
layer closest to the surface. It extends about 10km abovesea level.
Humans and plants livein this layer. Airplanes and birds also flyin this
layer. As the layers go higher, the airbecomes thinner.The other layers
include the stratosphere (50km abovesea level), mesosphere (85km
abovesea level), thermosphere (above500km abovesea level) and
exosphere.
How do the Earth's spheres interact?

All the spheres in the system interconnect and overlap.No sphere works on its
own.
 Thinkof the many ways that the hydrosphere and the atmosphere
connect. Evaporationfrom the hydrosphere provides the medium for
cloud and rain formation in the atmosphere.The atmosphere brings
back rainwater to the hydrosphere.
 In what way does the geosphere and hydrosphere connect?Water
provides the moisture and medium for weatheringand erosion of rocks

on in the geosphere.The geosphere, in turn,provides the platform for
ice melts and water bodies to flow back into the oceans.
 The atmosphere provides the geosphere with heat and energy needed
for rock breakdown and erosion.The geosphere, in turn,reflects the
sun's energy back into the atmosphere.
 The biosphere receives gases, heat,and sunlight (energy) from the
atmosphere.It receives water from the hydrosphere and a living
medium from the geosphere.

Food chains
All living things need to feed to get energy to grow, move and
reproduce. But what do these living things feed on? Smaller insects feed
on green plants, and bigger animals feed on smaller ones and so on. This
feeding relationship in an ecosystem is called a food chain.
A food chain is not the same as a food web.
A food web is a networkof manyfood chains and is more complex.
See the food web illustration below—youcan pick out a basic food chain from
the web:

Green plants -> Grasshopper -> Frog -> Bird -> Hawk
Energy transfer :-
Energy is transferred alongfood chains from one level to the next.Some
of the energy is used up in growth, reproduction repair,movement and other
ways, and not made available to the next level.

Trophic levels of food chains
The levels of a food chain (food pyramid)is called Trophic levels. The
trophiclevel of an organism is the level it holds in a food pyramid.
 The sun is the source of all the energy in food chains.Green plants,
usuallythe first level of any food chain, absorb some of the Sun’s light
energy to make their own food by photosynthesis.Green plants
(autotrophs)are therefore known as ‘Producers’ in a food chain.
 The second level of the food chains is called the Primary Consumer.
These consume the green plants.Animals in this group are usually
herbivores.Examples include insects,sheep,caterpillars and even cows.

 The third in the chain are Secondary Consumers. These usuallyeat up
the primaryconsumers and other animal matter.They are commonly
called carnivores and examples include lions,snakes and cats.
 The fourth level is called Tertiary Consumers. These are animals that eat
secondaryconsumers.
 Quaternary Consumers eat tertiaryconsumers.
 At the top of the levels are Predators. They are animals that havelittle
or no natural enemies.Theyare the ‘bosses’of theirecosystems.
Predators feed on preys.A prey is an animal that predators hunt to kill
and feed on. Predators include owls,snakes, wild cats, crocodiles and
sharks.Humans can also be called predators.
 When any organism dies, detrivores (like vultures,worms and crabs) eat
them up.The rest are broken down by decomposers (mostlybacteria
and fungi), and the exchange of energy continues.Decomposers start
the cycle again.

The Carbon Cycle
What is The Carbon Cycle?
The carbon cycle is very important to all ecosystems, and ultimatelylife
on earth.The carbon cycle is critical to the food chain.
Living tissue contains carbon,because theycontain proteins,fats and
carbohydrates.The carbon in these (livingor dead)tissues is recycled in
various processes.
Human activities like heatinghomes and cars burningfuels (combustion)
give off carbon into the atmosphere.Duringrespiration,animalsalso introduce
carbon into the atmosphere in the form of carbon dioxide.
The Carbon dioxidein the atmosphere is absorbed bygreen plants
(producers)to make food in photosynthesis.

When animals feed on green plants,theypass on carbon compounds
unto other animals in the upper levels of theirfood chains.Animals give off
carbon dioxide into the atmosphere duringrespiration.
Carbon dioxide is also given off when plants and animals die.This occurs
when decomposers (bacteria and fungi)break down dead plants and animals
(decomposition)and release the carbon compounds stored in them.
Very often,energy trapped in the dead materials becomes fossil fuels
which is used as combustion again at a later time.

Nitrogen Cycle
The Nitrogen Cycle
Nitrogen is also key in the existence of ecosystems and food chains.
Nitrogen forms about 78% of the air on earth.But plants do not use nitrogen
directlyfrom the air. This is because nitrogen itselfis unreactive,and cannot
be used by green plants to make protein.Nitrogen gas therefore, needs to be
converted into nitrate compound in the soil by nitrogen-fixingbacteria in soil,
root nodules orlightning.
1. Nitrogen is introduced into the soil by precipitation (rain,lightning).
2. Nitrates don’t onlycome from Nitrogen in the air. Theycan also be
obtained bythe conversion of ammonia,commonlyused in fertilizers
by nitrifyingbacteria in the soil.Some root nodules can also convert
nitrogen in the soil into nitrates.

3. Plants build up proteins usingnitrates absorbedfrom the soil.
4. When animals like cows, eat these plants,they,in turn,use it to build
animal protein.
5-6. When these animals (cows) poop,pee or die, the urea,excreta or
carcass are broken down by decomposers and the nitrogen is re-introduced
into the soil in the form of ammonia.
7. Nitrates in the soil can also be broken down by denitrifyingbacteria
(in specific conditions)and sent into the airas nitrogen.This process can
help make the soil infertile because it will lack the nitrates needed for plant
use.
Once nitrogen gets back into the air, the cycle
continues.

Important ecosystem terminology
1. EcosystemServices:
This the technical term for the benefits humans and other living
things get from ecosystems. These services are in four groups:Supporting
services, Provisioningservices,Regulatingservices and Cultural services.
Benefitsof ecosystems
The interaction oflivingthings dependingon each other and relatingto
theirenvironments has immense benefits in terms of the health and spiritual
wellbeingof humans,the health of members of the ecosystem themselves,as
well as the environment.Livingthings do not exist in isolation.Theydepend on
abioticfactors too. The benefit of ecosystems therefore is not exclusiveto
livingthings.So, what is the role of ecosystems?
A. Supportive
Ecosystems provide a supportingrole for all its members.In this
role, livingmembers serve as food for others,and their produce and
residue serve as nutrients to soils and gases to the atmosphere.This
makes soil nutrient cycle, carbon and oxygen cycle and water cycle
possible and also forliving things to continue procreation.
B. Provision
Ecosystems are also the source of all foods,store of all energy, fibre,
genetic resources, medicines,fresh water and minerals. All natural
resources that humans depend on,has its source from ecosystems.

C. Regulation
The function ofa healthyecosystem ensures that there is balance and
regulation in the climate, regulation in fresh water, soils,rocks, and
atmosphere.Theyfunction to regulate animals and plant diseases and
ensure that biodiversityis preserved.
D. Spiritual Value
Perhaps not exclusiveto humans,ecosystems provide humans with
deeper spiritual enrichment and cognitivedevelopment.The wonder and
breathtakingproperties ofhealthyecosystems has recreational effects,as
well as aestheticvalue to us. From land the remotest places on earth to the
deepest places in the oceans,there are millions oflife forms that function
in harmony,and provide humans with meditativeand healingbenefits.
2. Adaptation :
An adaptation is a way an animal's bodyhelps it survive, or live,in its
environment.A good example is the polarbear.Its while fur helps it to
camouflage, so its prey cannot see it. Its Thick fur also provides the warmth
to help it survivein its frozen environment.
3. Abiotic :
Physical,or nonliving,factors that shape an ecosystem. Examples
include rocks, climate, pressure, soils,precipitation,sunlight,winds and
humidity.These abiotichavea direct influence on livingthings.

4. Biotic:
Living factors such as plants,animals,fungi,protist and bacteria are
all bioticor living factors.Biotic factors depend on abioticfactors to
survive. Th kind of bioticfactors (living organisms)in a given area is often
as a result of abioticconditions ofthat area.
5. Symbiosis:
Relationship in which two species liveclosely together, usually
benefitingfrom each other.There are three types of this relationship:
1. Parasitism : - parasite benefits,the host is hurt.
2. Commensalism : - one species benefits,the other is neither hurt nor
helped.
3. Mutualism : - both species benefit
6. Food Web:
The complex feeding networkoccurring within and between food
chains in an ecosystem, whereby members of one food chain may
belongto one or more other food chains.
7. Habitat :
The place where a particularpopulation(e.g., human,animal, plant,
microorganism)lives and its surroundings.Example, The anaconda snake
lives in water and thrives very well there.
8. Plankton :
Microscopic plants and animals that livein water.

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