IB Eco system Chapter

• 2.1 Structure of Eco System

Organism :
• An organism is a fundamental functional
unit in ecology because it interacts
directly with the environment as well as
with other organism
e.g., Rabbits
What is Organism ?

What is Population?
• It refers to the organism of the same
species that are in proximity to one
another
• e.g., A group of rabbit

What is Community?
• This includes all the populations occupying a
given area.
• The size of the community depends on our
scale of reference
• The community and the non-living
environment together are referred to as an
ECOLOGICAL SYSTEM or ECOSYSTEM
• e.g., pond fish and plants

• A species is often defined as a group
of organisms capable of interbreeding and
producing fertile offspring.
What is species?

• A habitat is an ecological or environmental area that
is inhabited by particular species of animal, plant or
other type of organism.
• It is the natural environment in which an organism
lives, or the physical environment that surrounds a
species population.
What is habitat?

Biosphere
Ecosystems
Communities
Populations
Organisms

• In biology, a species is one of the basic
units of biological classification .
• A species is often defined as a group
of organisms capable of interbreeding and
producing fertile offspring.
What is species?

• A habitat is an ecological or environmental area that is
inhabited by particular species of animal, plant or other
type of organism.
• It is the natural environment in which an organism lives,
or the physical environment that surrounds a
species population.
What is habitat?

• An ecosystem has two basic components
• ABIOTIC COMPONENTS
• BIOTIC COMPONENTS

• Biotic components is classified into
three categories:
• PRODUCERS-Autotrophic
• CONSUMERS -Heterotrophic
• DECOMPOSERS OR
SAPTROTROPHS
Biotic Components

• Producers are things such as plants that are fed
off of but do not eat other producers or
organisms.
• Consumers are organisms (including us
humans) that get their energy from producers,
regarding the flow of energy through an
ecosystem

• A decomposer is an organism of decay.
• These are also called saprobes.
• They break down the remains of dead animals
and plants, releasing the substances that can be
used by other members of the ecosystem

• The non living ,physical and chemical
components of an ecosystem are called the
abiotic factors and include:
• Light
• Temperature,
• Water,
• Soil
• The atmosphere
• Climate –Light intensity, temperature range,
precipitation
What is Abiotic components?

• In ecology, a niche is a term describing the way
of life of a species.
• Each species is thought to have a separate,
unique niche.
• The ecological niche describes how an organism
or population responds to the distribution of
resources and competitors
What is NICHE?

• One example is squirrels that collect acorns and bury
them for winter.
• Another is honeybees that gather nectar from flowers
to make honey.
• Other organisms that may exist in the same
environment don't do this.
• For instance, a bird may live in the same tree as a
beehive, but the bird does not make honey the way
the bees do. That is not its niche.
Example for NICHE

What is Eco System?
• A dynamic complex of plants, animals and
micro organisms inhabiting a particular area
with their non living environment interacting
as a functional unit

2.1.3 Identify and explain trophic levels
in food chains and food webs selected
from the local environment.

• Trophic levels are the feeding position in a food
chain such as primary producers, herbivore,
primary carnivore, etc.
• Green plants form the first trophic level, the
producers.
• Herbivores form the second trophic level, while
carnivores form the third and even the fourth
trophic levels.
What is Trophic levels?

• The feeding of one organism upon another in a
sequence of food transfers is known as a food
chain.
• Food chain is the chain of transfer of energy
from one organism to another. A simple food
chain is like the following:
• rose plant -- aphids -- beetle -- chameleon --
hawk.
What is Food chain?

• In an ecosystem there are many different food
chains and many of these are cross-linked to
form a food web.
• Ultimately all plants and animals in an
ecosystem are part of this complex food web.
What is food web?

Phytoplankton are the autotrophic/producers
of the ocean

2.1.4 Explain the principles of pyramids of
numbers, pyramids of biomass, and
pyramids of productivity, and construct
such pyramids from given data.

 Trophic levels and the energy flow from one
level to the next, can be graphically depicted
using an ecological pyramid.
 Three types of ecological pyramids can
usually be distinguished namely:
1. Pyramids of numbers
2. Pyramid of biomass
3. Pyramids of productivity
What is Ecological Pyramids?

Pyramids of numbers
• A pyramid of numbers is a graphical
representation of the numbers of
individuals in each population in a food
chain.
• A pyramid of numbers can be used to
examine how the population of a certain
species affects another

PYRAMID OF NUMBERS represents storages
found at each trophic level.
Units vary

Grassland
(summer)
Temperate Forest
(summer)
Producers
Primary consumers
Secondary consumers
Tertiary consumers
A few large producers (the trees) support a much larger number of
Small primary consumers (insects) that feed on the trees.

Pyramids of Numbers
Advantages
• Overcomes the problems of pyramids of
number.
Disadvantages
• Only uses samples from populations, so it is
impossible to measure biomass exactly. also
the time of the year that biomass is measured
affects the result.

Pyramid of biomass
• The total amount of living or organic matter
in an ecosystem at any time is called
'Biomass’.
• Pyramid of biomass is the graphic
representation of biomass present per unit
area of different tropic levels, with producers
at the base and top carnivores at the tip".

• Represents the standing stock of each trophic
level (in grams of biomass per unit area g / m2)
• Represent storages along with pyramids of
numbers

PYRAMID OF BIOMASS represent the
standing stock at each trophic level.
Units:
J m-2
or
g m-2

Abandoned Field Ocean
Tertiary consumers
Secondary consumers
Primary consumers
Producers
In open waters of aquatic ecosystems, the biomass primary consumers
(zooplankton) can exceed that of producers. The zooplankton eat the
Producers (phytoplankton) as fast as they reproduce, so their population
is never very large.

How do we get the biomass of a trophic level to
make these pyramids?
• Take quantitative samples – known area or volume
• Measure the whole habitat size
• Dry samples to remove water weight
• Take Dry mass for sample then extrapolate to entire trophic
level
• Evaluation  It is an estimate based on assumption that
– all individuals at that trophic level are the same
– The sample accurately represents the whole habitat

• Analysis of various ecosystems indicates that
those with squat biomass pyramids are less
likely to be disrupted by physical or biotic
changes than those with tall, skinny pyramids
(having conversion efficiencies less than 10%).

Measurement of biomass of different
trophic levels in an ecosystem.

Describe one method for the measurement of biomass of
different trophic levels in an ecosytem.
• Representative samples of all living organisms
in the ecosystem are collected, for example
from randomly positioned quadrats.
• The organisms are dried, by being placed in an
oven at 60-80 C.
• The mass of organisms in each trophic level is
measured using an electronic balance.

Multiply the mean height by the stem density

• Biomass can be assessed indirectly and
completely non destructively by counting the
number of individuals of the target speices
• Randomly selecting a sample of individuals
• Determining mean height within the sample
(height will be an indirect measure of biomass)
• Multiply the mean height by the stem density
(number of individuals)

• A more destructive method involves taking a
sample of individuals of the target species and
cutting them at soil level.
• Tag each individual with a label, dry it to a
stable weight and weigh it.
• Determine the mean mass of the plants in the
area and multiply by the stem density in the
area.

Pyramids of Productivity
• A graphical representation in the shape of
a pyramid showing the distribution of
productivity or flow of energy through
the tropic levels.

producers
10 J m-2 yr-1
100 J m-2 yr-1
1,000 J m-2 yr-1
10,000 J m-2 yr-1

PYRAMID OF PRODUCTIVITY represents
the flow of energy through each trophic level.
Units:
J m-2 yr-1
or
g m-2 yr-1

Pyramids of productivity
• Flow of energy through trophic levels
• Energy decreases along the food chain
– Lost as heat
• Productivity pyramids ALWAYS decrease as
they go higher – 1st and 2nd laws of
thermodynamics
• Productivity measured in units of flow (J /
m2 yr or g / m2 yr ) Joule per square metre in
year/

• As you move up each trophic level, only
10% of the energy is transferred.
• The other 90% is used for everyday life
functions, metabolism.

Pyramid structure
affects
the functioning of
an
ecosystem.
Bioaccumulation

Pyramids of productivity
• Advantages
• Most accurate system shows the actual energy
transferred and allows for rate of production.
• Disadvantages
• It is very difficult and complex to collect
energy data.

PYRAMID OF STANDING CROP
• Pyramid diagrams may show the fixed quantity
of number, biomass or energy that exists at a
particular time in a given area or averaged
from many of these measurements.
• This is termed STANDING CROP.
• The unit would be number,dry biomass or
energy kg/m2 or J/m3.

Figure 54.14 Food energy available to the human population at different trophic levels
Efficiency of trophic levels in relation to the total energy
available decreases with higher numbers
But efficiency of transfer always remains around that 10% rule

• ENERGY FLOW THROUGH
• PRODUCERS
• CONSUMERS
• DECOMPOSERS

Energy Flow through Producers
• Producers convert light energy into chemical
energy of organic molecules
• Energy lost as cell respiration in producers
then as heat elsewhere
• When consumers eat producers energy passes
on to them
• In death organic matter passes to saprophytes
& detritivores

Energy Flow through Consumers
• Obtain energy by eating producers or other
consumers
• Energy transfer never above 20% efficient,
usually between 10 – 20%
• Food ingested has multiple fates
1. Large portion used in cell respiration for meeting
energy requirements (LOSS)
2. Smaller portion is assimilated used for growth,
repair, reproduction
3. Smallest portion, undigested material excreted as
waste (LOSS)

Figure 54.10 Energy partitioning within a link of the food chain

Energy flow through Decomposers
• Some food is not digested by consumers so
lost as feces to detritivores & saprophytes
• Energy eventually released by process of cell
respiration or lost as heat

2.1.5 Discuss how the pyramid
structure affects the functioning of an
ecosystem.

How does pyramid structure effect
ecosystem function?
1. Limited length of food chains
• Rarely more than 4 or 5 trophic levels
• Not enough energy left after 4-5 transfers to
support organisms feeding high up
• Possible exception marine/aquatic systems b/c
first few levels small and little structure
2. Vulnerability of top carnivores
• Effected by changes at all lower levels
• Small numbers to begin with
• Effected by pollutants & toxins passed through
system

What is Biomagnification?
• Biomagnification is the sequence of processes
in an ecosystem by which higher
concentrations of a particular chemical, such
as the pesticide DDT, are reached in organisms
higher up the food chain, generally through a
series of prey-predator relationships.

What is bioaccumulation?
• Bioaccumulation refers to the accumulation of
substances, such as pesticides, or other organic
chemicals in an organism.
• Bioaccumulation occurs when an organism
absorbs a toxic substance at a rate greater.

• 2.1.7 -Describe and explain population
interactions using examples of named species.

• In ecology, predation describes a biological
interaction where a predator feeds on its prey.
• Examples :Lion killing buffalo, Eagle killing
Rabbit, Mantis eating a bee.
Predation

• Herbivores are organisms that are adapted to
eat plants.
• Herbivory is a form of predation in which an
organism consumes principally autotrophs
such as plants, algae and photosynthesizing
bacteria.
Herbivore

• Parasitism is a type of symbiotic relationship
between organisms of different species where
one organism, the parasite, benefits at the
expense of the host.
Example :
• Mosquito: Females ingest blood for the
protein. Male mosquitos ingest plant juices.
• Heartworm of dogs, whose adults reside in the
right side of the heart
Parasitism

Mosquito: Females ingest blood for the protein. Male
mosquitos ingest plant juices

Heartworm of dogs, whose adults reside in the right side of the heart

• Mutualism is a biological interaction that is
beneficial to both parties.
• Mutualism is the way two organisms biologically
interact where each individual derives a fitness
benefit (i.e. increased survivorship).
• Examples :Clownfish and sea anemones, langur
monkey curing cow's ear
Mutualism

2.3.5 APPLY SIMPSON’S DIVERSITY INDEX
AND OUTLINE ITS SIGNIFICANCE
Simpson’s Diversity Index

1) Simpson's diversity index (also known as
species diversity index) is one of a number of
diversity indices, used to measure diversity.
2) In ecology, it is often used to quantify the
biodiversity of a habitat.
3) It takes into account the number of species
present, as well as the relative abundance of each
species.
4) The Simpson index represents the probability that
two randomly selected individuals in the habitat
will not belong to the same species.

• For plant species the percentage cover in a
square is usually used;
• For animal species, for example in a river, the
number of organisms of a species is used.
• The reason percentage cover is used is because
it is usually very difficult to count all the
individual plants

• Where:
• D = diversity index
N = total number of organisms of all species found
n = number of individuals of a particular species

Species Number of individuals in
Ecosystem 1
Number of individuals in
Ecosystem 2
A 23 2
B 28 2
C 22 1
D 27 93
Total individuals in
ecosystem
100 98

Simpson’s Diversity Index =
• [23x(23-1)] + [28x(28-1)] + [22x(22-1)] +[27x(27-1)]
100 x (100 – 1)
=4.08
• For Ecosystem 2:
• Simpson’s Diversity Index =
• 2x(2-1)] + [2x(2-1)] + [1x(1-1)] + [93x(93-1)]
98 x (98 – 1)
= 1.11

RESULT
• From this it can be seen that ecosystem 1 has
the highest index of diversity.
• The larger then Simpson’s index the more
diverse.
• Increasing diversity tends to suggest more
stable ecosystems with more connections
within them.

2.2.2 Abiotic factors in Marine
Ecosystems
Describe and evaluate methods
for measuring at least three
abiotic (physical) factors within an
ecosystem.

What are Limiting Factors of an
ecosystem?
• Limiting factors are physical or
biological necessities whose
presence or absence in
inappropriate amounts limits the
normal action of the organism.

Limiting factor for Marine
Ecosystem
• Light
• Temperature
• Salinity
• Dissolved Gases
• Pressure

Light is needed for photosynthesis and
vision.
• Blue light penetrates deepest.

Temperature influences
the metabolic rate, the
rate at which reactions
proceed within an
organism.

What is the Deepest Part of the Ocean?
• The ocean's deepest area is
the CHALLENGER DEEP (also called the
Marianas Trench), which is about 11 km
(almost 7 miles, or almost 36,000 feet) deep.
• The trench is 1,554 miles long and 44 miles
wide,

• Most marine organisms are
ECTOTHERMIC having an internal
temperature that stays very close to
that of their surroundings.
• A few complex animals (mammals &
birds) are ENDOTHERMIC, meaning
they maintain a stable internal
temperature.
• Ocean temperature varies in both
depth and latitude.
• Ocean temperatures vary less than on
land.

Salinity greatly affect cell membranes and
protein structure.
• Disrupts cells osmotic pressure.
• Varies because of rainfall, evaporation and
runoff from land.

How deep is the ocean?
The average depth of the ocean is about 4,267
meters (14,000 feet).
The deepest part of the ocean is called the
Challenger Deep and is located beneath the
western Pacific Ocean in the southern end of
the Mariana Trench, which runs several
hundred kilometers southwest of the U.S.
territorial island of Guam.
Challenger Deep is approximately 11,030
meters (36,200 feet) deep.

GASES
Dissolved Gases are necessary for
photosynthesis and respiration.
• CO2 dissolves more easily in water than O2.
• CO2 is more abundant in deep waters than
surface water.
• O2 decrease dramatically where light
penetration decreases.

How deep can humans go
underwater?
• Breathing air, humans can go down around
350 feet without any sort of protection from
pressure
• Utilizing mixed gases, a diver can reach a little
over 300 meters

Pressure from the layers of water above.
• Increases with increasing depth.
• To counteract the mass of heavy
muscles and bone, many swimming
fishes have gas-filled bladders.
• Deep-sea fish don’t have gas bladders,
but light bones and oily watery flesh.

Marine Zones
• Areas of homogeneous physical
features.
• Usually based on light, temperature,
salinity, depth, latitude, behavior
and/or water density.

By light
• Upper zone is called the Euphotic
zone and is where the rate of
photosynthesis is high.
• Lower zone is called Disphotic zone
and is where organisms can see, but
there is sufficient light for
photosynthesis.
Aphotic zone where no light
penetrates.

By Location
Pelagic zone between water and ocean
bottom.
a. Neritic zone = near shore over the
continental shelf

b. Oceanic zone = deep-water beyond the
continental shelf.
i. Epipelagic = photic zone of the ocean.
ii. Mesopelagic = middle ocean waters.
iii. Bathypelagic = ocean floor.
iv. Abyssopelagic = deep-ocean trenches.

MEASURING THE ABIOTIC
FACTORS
You should be able to describe & evaluate three
methods in details with references to a named
ecosystem

1.TEMPERATURE:-Normally measured using
thermometers or temperature probes attached
to data logger.
Seasonal & diurnal variations important ,as is
the influence of aspect

2.LIGHT INTENSITY:
• This measured using a light meter in lux.
• Seasonal,latitide influence incident the radiation

3.SOIL:
• Soil organic matter is assessed by baking in the
oven at over 100 degrees to evaporate off the
water and given as percentage of original soil
mass

4.WIND SPEED:
• This is measured using an anemometer; an
instrument with cuts that spin in the wind

5.SALINITY:
• This measured using refractometer by placing
a droplet of sample water on a lens and
allowing light to enter through the water

6.PH:
• This measured using universal indicator or a pH
probe
7.Turbidity
• Measured in depth(m) using a sechi
disc(black& white decorated disc) lowered on a
measuring rope until it is no longer visible

The Secchi disk measures the transparency of the water. Transparency can be
affected by the color of the water, algae, and suspended sediments. Transparency
decreases as color, suspended sediments, or algal abundance increases.

SPECIES IDENTIFICATION
• This is usually done with a published
identification key.
• The key asks a question and the answer
determines what step to go to next, either the
name of the species or another question

(presence/absence of legs;
number of legs;
presence/absence of tentacles;
number of tentacles;
shape;
visible eyes;
bristles

DIRECT METHODS OF ESTIMATING
OF ABUNDANCE IN ANIMALS
• Animals that don’t move quickly, such as
rocky shore limpets or grassland snails, can be
counted in quadrats giving a direct measure of
population density.
• This only suitable for species that don’t run
away
• A variety of direct sampling techniques can be
used to collect invertebrates using nets and
traps

Methods for Estimating Population Size
1. Quadrats
2. Capture/Mark/Release/Recapture (Lincoln
Index)

• Knowing population size is important in
making environmental decisions that would
affect the population.
• Making a decision on an estimate that is too
high  extinction.
• Making a decision on an estimate that is too
low  unnecessarily hurt people that depend
on the animals for food & income.
Why we should know the population size of
an ecosystem?

• ESTIMATING THE
POPULATION USING THE
NETS

1.Freshwater nets for lake and stream
invertebrates

2.Sweep nets for grassland and scrub
Sweep nets are sturdy nets used to collect
insects from long grass.

4.Pit trapping and baited traps for terrestrial
invertebrates

5.Beating trays for invertebrates in trees

• When estimating population size it is
important to collect RANDOM
SAMPLES.
• A sample is a part of a population, part of
an area or part of some other whole thing,
chosen to illustrate what the whole
population, area or other thing is like.
• In a random sample every individual in a
population has an equal chance of being
selected.

Coconut tree
Grass
Which one is easy to calculate the biomass?
Problems?
Problems?

Using Quadrats
1. Mark out area to be sampled.
2. Place quadrates ( 1 m2, 10 m2) randomly
within the area.
3. Count how many individuals are inside
each of the quadrates.
4. Calculate the mean number of
individuals per quadrate.
5. Pop. Size = mean x total area
area of each Quadrat

RANDOM
QUDRATS
SYSTEMATIC
QUDRATS
Quadrat sampling is suitable for
plants that do not move around and
are easy to find.

Quadrat method can be used to determine:
 POPULATION DENSITY = number of
individuals of each species per area.
 PERCENTAGE FREQUENCY =
percent of each species found within an
area.
 PERCENTAGE COVER = percent of
plant covering a given area.

Capture/Mark/
Release/Recapture
Lincoln index
1. Capture as many individuals as possible in the
area occupied by the animal population, using
netting, trapping or careful searching.
2. Mark each individual, without making them
more visible to predators and without harming
them.

3. Release all the marked individuals and allow
them to settle back into their habitat.
4. Recapture as many individuals as possible
and count how many are marked and how
many are unmarked.
10 marked
14 unmarked

Assumptions:
1. The population of organisms must be closed, with
no immigration or emigration.
2. The time between samples must be very small
compared to the life span of the organism being
sampled.
3. The marked organisms must mix completely with
the rest of the population during the time between
the two samples.
4. Organisms are not hurt or disadvantaged by being
caught and marked and therefore all organisms have
an equal opportunity of being recaptured

Calculate the estimated population size by using
the Lincoln Index:
population size = N1 X N2
N3
N1 = number caught and marked initially
N2 = total number caught in 2nd sample
N3 = number of marked individuals recaptured
Most suitable for animals that move around and
are difficult to find.

Change in the relative abundance of a
species over an area or a distance is
referred to as an ECOLOGIAL GRADIENT
Also known as Zonation.

What is Environmental gradient?
• An environmental gradient is a gradual
change in abiotic factors through space (or
time). Environmental gradients can be related
to factors such as latitude, temperature, depth,
ocean proximity and soil humidity.

Changes in the distribution of animals with
elevation on a typical mountain in Kenya. Another
example of Zonation

BIOME is the collection of ecosystems
sharing similar climatic conditions.

Uneven Solar Heating and Latitude
Earth as a whole is in thermal equilibrium, but different latitudes are not.
Moving masses of air and ocean currents transport energy from
locations with a surplus to those with a deficit.

Cell 3 South
Cold,
dry air
falls
Moist air rises — rain
Cell 2 South
Cool, dry
air falls
Cell 1 South
Moist
air rises,
cools, and
releases
moisture
as rain
Cell 1 North
Cool, dry
air falls
Cell 2 North
Moist air rises — rain
Cell 3 NorthCold,
dry air
falls
Polar cap
Arctic tundra
60°
30°
0°
30°
60°
Polar cap
Evergreen
coniferous forest
Temperate deciduous
forest and grassland
Desert
Tropical deciduous forest
Equator
Tropical
rain forest
Tropical deciduous forest
Desert
Temperate deciduous
forest and grassland
Model of global air
circulation and
biomes.
The direction of air
flow and the ascent
and descent of air
masses in
convection cells
determine the
earth’s climatic
zones.

Mountain
Ice and snow
Altitude
Tundra (herbs,
lichens,
mosses)
Coniferous
Forest
Tropical
Forest
Deciduous
Forest
Tropical
Forest
Deciduous
Forest
Coniferous
Forest
Tundra (herbs,
lichens, mosses)
Polar ice
and snow
Latitude
Generalized effects of altitude and latitude on climate and biomes.
Parallel changes in vegetation occur when moving from the
Equator to the poles or from the lowlands to mountaintops.

DIVERSITY is a generic term for the following
points
1. Genetic diversity is the total number of genetic
characteristics of a specific species.
2. Habitat diversity is the diversity of habitats in a given
unit area.
3. Species diversity
a. Species richness – total number of species.
b. Species evenness – relative abundance of each
species.
c. Species dominance – the most abundant species.

Figure A and B have
the same species
richness, but
different species
evenness.
A
B

What is Biome?
A biome is a specific area characterized by
the animals and plants that live within it,
the climate conditions, the amount of water
available, the soil conditions, and the
location of the area.

• The seven main biomes that can be found all
over the world.
• The Desert, Grasslands, Temperate
Deciduous Forests, Rainforests, Taiga, and
the Tundra

CLASSIFICATION OF BIOMES
A fundamental classification of biomes is into:
• Terrestrial (land) biomes
• Freshwater biomes
• Marine biomes

Terrestrial (land) biomes
Freshwater biomes
Marine biomes

What is tropical rainforest ?
A tropical rainforest is an ecosystem usually
found around the equator.
They are common in Asia, Australia, Africa,
South America, Central America, Mexico and
on many of the Pacific Islands.

Rainforests are home to half of all the living
animal and plant species on the planet.
Tropical rain forests are called the "world's
largest pharmacy" because over one-quarter of
modern medicines originate from its plants.

DISTRIBUTION
The tropical forests are restricted to the small land
area between the latitudes 22.5 North and 22.5
South of the equator, or in other words between
the Tropic of Capricorn and the Tropic of Cancer.
Since the majority of Earth's land is located north
of the tropics, rainforests are naturally limited to a
relatively small area.

Major Tropical rain Forest Area
CENTRALAMERICA
THE AMAZON
AFRICA
SOUTHERN ASIA
AUSTRALASIA

CENTRALAMERICA
Central America is famous for its large number
of tropical birds, including many kinds of
parrots
This region was once entirely covered with
rainforest, but large areas have been cleared for
cattle ranching and for sugar cane plantations.

The photograph below shows a particular ecosystem.
1.State and briefly describe the ecosystem shown in the photograph
2. State whether you would expect ecosystems of the type shown in the
photograph to have a low, medium or high level of abiotic factors.

THE AMAZON
 The Amazon is the world's largest and most famous
rainforest.
 The Amazon is home to more species of plants and
animals than any other ecosystem on the planet and
perhaps 30% of the world's species are found there.
 American rainforests are most threatened today with
large-scale agriculture (especially soybeans), clearing
for cattle pasture, subsistence agriculture by poor
farmers, and logging.

AFRICA
Central Africa holds the world's second largest
rainforest.
To the south east, the large island of Madagascar
was once intensively forested, but now much of it
is gone.
The island of Madagascar is home to many unique
plants and animals not found anywhere else.

SOUTHERN ASIA
• The rainforests of Asia stretch from India and
Burma in the west to Malaysia and the islands
of Java and Borneo in the east.
• In Southeast Asia the climate is hot and humid
all year round. In the mainland Asia it has a
subtropical climate with torrential monsoon
rains followed by a drier period.

What is Freshwater Biome?
The freshwater biome is a low-saline, or sweet
water, aquatic biome that covers one fifth of
the earth's surface.
Streams, rivers, swamps, bogs, ponds, lakes,
ditches, puddles, and canals comprise the
tributaries of the freshwater biome.

TYPES OF FRESHWATER
• There are 3 different types of freshwater
regions:
Ponds and Lakes
Streams and Rivers
Wetlands

These regions range in size from just a few
square meters to thousands of square
kilometers. Scattered throughout the earth.
Many ponds are seasonal, lasting just a couple
of months.
Ponds and lakes may have limited species
diversity since they are often isolated from one
another and from other water sources like
rivers and oceans.

For the organism you have chosen, describe and evaluate a method for estimating
its abundance.

Streams and rivers
These are bodies of flowing water moving in
one direction.
Streams and rivers can be found everywhere
— they get their starts at headwaters, which
may be springs, snowmelt or even lakes, and
then travel all the way to their mouths, usually
another water channel or the ocean.

Numerous aquatic green plants and algae can
be found in these bodies.
Since there is less light, there is less diversity
of flora, and because of the lower oxygen
levels, fish that require less oxygen, such as
catfish and carp, can be found.

1.Name an organism in an ecosystem that you have studied and state one abiotic
factor that might affect this organism.
Organism:
.........................................................................................................
Factor:
...............................................................................................................

Wetlands
Wetlands are areas of standing water that
support aquatic plants.
 Marshes, swamps, and bogs are all considered
wetlands. Plant species adapted to the very
moist and humid conditions are called wetland
flora.

What is Marine Biome?
The marine biome includes all the water that is on
the earth's surface.
The marine biome covers three fourths of the earth.
There are thousands of animals and plants in the
biome.
or
Marine regions cover about three-fourths of the
Earth's surface and include oceans, coral reefs, and
estuaries

Marine Biomes are classified into three types.
• Coral reefs
• Estuaries
• Oceans

Oceans
The largest of all the ecosystems, oceans are very
large bodies of water that dominate the Earth's
surface.
The ocean regions are separated into separate
zones: intertidal, Pelagic, Abyssal, and Benthic.
All four zones have a great diversity of species.

The intertidal zone is where the ocean meets the
land — sometimes it is submerged and at other
times exposed, as waves and tides come in and
out.
The pelagic zone includes those waters further
from the land, basically the open ocean.
The pelagic zone is generally cold though it is
hard to give a general temperature range since,
just like ponds and lakes

The benthic zone is the area below the pelagic
zone, but does not include the very deepest
parts of the ocean
The bottom of the zone consists of sand, slit,
and/or dead organisms.
The deep ocean is the abyssal zone. The water
in this region is very cold (around 3 C), highly
pressured, high in oxygen content, but low in
nutritional content.

Characteristics of tundra include:
• Extremely cold climate
• Low biotic diversity
• Simple vegetation structure
• Limitation of drainage
• Short season of growth and reproduction
• Energy and nutrients in the form of dead
organic material
• Large population oscillations

• Tundra is separated into two types:
• Arctic tundra
• Alpine tundra

Biomes of the World
1. The Tundra
2. Low biotic diversity
Alpine vs Arctic tundra
1. Extremely cold climate
3. Simple vegetation structure
4. Permafrost
5. Short growing season
6. Energy and nutrients in the form
of dead organic material
7. Large population oscillations

Arctic tundra
• Arctic tundra is located in the northern
hemisphere, encircling the north pole and
extending south to the coniferous forests of the
taiga.
• The growing season ranges from 50 to 60 days.

• There are no deep root systems in the
vegetation of the arctic tundra, however, there
are still a wide variety of plants that are able
to resist the cold climate.
• There are about 1,700 kinds of plants in the
arctic and subarctic, and these include:
• Low shrubs, sedges, reindeer mosses,
liverworts, and grasses

• Animals are adapted to handle long, cold
winters and to breed and raise young quickly
in the summer.
• Animals such as mammals and birds also
have additional insulation from fat.
• Many animals hibernate during the winter
because food is not abundant.

Alpine tundra
• Alpine tundra is located on mountains
throughout the world at high altitude where
trees cannot grow.
• The growing season is approximately 180
days.
• The nighttime temperature is usually below
freezing. Unlike the arctic tundra, the soil in
the alpine is well drained.

• The plants are very similar to those of the arctic
ones and include:
• tussock grasses, dwarf trees, small-leafed shrubs,
and heaths
• Animals living in the alpine tundra are also well
adapted:
• Mammals: Pikas, marmots, mountain goats, sheep,
elk
• Birds: grouselike birds
• Insects: springtails, beetles, grasshoppers, butterflies

The desert biome
• Deserts cover about one fifth of the Earth's
surface and occur where rainfall is less than
50 cm/year.
• Most deserts have a considerable amount of
specialized vegetation, as well as specialized
vertebrate and invertebrate animals.

• Desert biomes can be classified according to
several characteristics.
There are four major types of deserts:
• Hot and dry Desert
• Semiarid Desert
• Coastal Desert
• Cold Desert

Hot and dry desert
• Hot and dry desert present in North American
countries.
• The seasons are generally warm throughout the
year and very hot in the summer.
• The winters usually bring little rainfall.

• Desert surfaces receive a little more than twice
the solar radiation received by humid regions .
• The animals include small nocturnal (active at
night) carnivores.
• The dominant animals are burrowers and
kangaroo rats. There are also insects, arachnids,
reptiles and birds.

Semiarid Desert
• The major deserts of this type include the
• Sagebrush of Utah,
• Montana and Great Basin.
• They also include the North America,
Newfoundland, Greenland, Russia, Europe and
northern Asia.

Coastal desert
• These deserts occur in moderately cool to
warm areas is the coastal desert.
A good example is the Atacama of Chile.
• The soil is fine-textured with a moderate salt
content.

Salt bush Buckwheat bush
Little leaf horse brush

Cold desert
• These deserts are characterized by cold winters
with snowfall and high overall rainfall
throughout the winter and occasionally over the
summer.
• They occur in the Antarctic, Greenland and the
Nearctic realm. They have short, moist, and
moderately warm summers with fairly long,
cold winters.

• The heaviest rainfall of the spring is usually in
April or May. In some areas, rainfall can be
heavy in autumn.
• The burrowing habit also applies to carnivores
like the badger, kit fox, and coyote.

Chapter : 2.5.2
Topic : Photosynthesis & Respiration
in Energy Transformation

What is Photosynthesis?
• Conversion by plants of light energy into chemical
energy, which is then used to support the plants'
biological processes.
• Process by which cells containing chlorophyll in
green plants convert incident light to chemical energy
and synthesize organic compounds from inorganic
compounds, especially carbohydrates from carbon
dioxide and water, accompanied by the simultaneous
release of oxygen

Photosynthesis in Plants
• Chloroplasts are the location of photosynthesis in
plants
• Green color from chlorophyll (photosynthetic
pigment)
• Found in cells of mesophyll – interior tissue of
leaves
• Gases exchanges through the stomata
• Water enters through xylem of roots

What is Respiration ?
• The process by which oxygen is taken in and
used by tissues in the body and carbon dioxide
is released.
• The energy producing process of breathing, by
which an organism supplies its cells with
oxygen and relieves itself of carbon dioxide.

Figure 10.2 Focusing in on the location of photosynthesis in a plant

What is ATP
• ATP stands for adenosine triphosphate, which
is a compound that a cell uses to store energy.
• In plant photosynthesis, the plant takes in
carbon dioxide as well as sunlight and releases
oxygen.
• ATP plays a role in making the proper
conversion so the plant can use the energy.

Energy Processes
• Photosynthesis (Green Plants)
sunlight +water + carbon dioxide  oxygen + sugars(Glucose)
• Respiration (All living things)
oxygen + sugars  ATP +water + carbon dioxide
• ATP is molecular energy storage

Photosynthesis
• Inputs – sunlight, carbon dioxide, water
• Outputs – sugars, oxygen
• Transformations – radiant energy into chemical
energy, inorganic carbon into organic carbon
Inputs, Output & Transformation

Respiration
• Inputs - sugars, oxygen
• Outputs - ATP, carbon dioxide, water
• Transformations – chemical energy in carbon
compounds into chemical energy as ATP,
organic carbon compounds into inorganic
carbon compounds
Inputs, Output & Transformation

• The fundamental energy source for most of the
environment is the sun.
• Photoautotrophs capture the sun’s energy and use it to
make organic compounds through photosynthesis.
• Photoautotrophs are often also called primary
producers because they establish the basis for most
other production; they create organic material from
inorganic, or non-living, sources.
• The process of photosynthesis transforms carbon
dioxide and water into simple carbohydrates.

2.5.5-- Define the terms gross productivity, net
productivity, primary productivity and
secondary productivity.

• Gross productivity (GP)
• Gross Primary Productivity (GPP)
• Gross Secondary Productivity (GSP)
• Net productivity
• Net Primary Productivity (NPP)
• Net Secondary Productivity (NSP)
• Primary productivity
• Secondary productivity

2.5.5-.7 Productivity
http://www.nature.com/scitab
le/knowledge/library/second
ary-production-13234142

• The primary productivity is the amount of energy or
biomass produced through photosynthesis per unit area
and time by plants.
• Primary productivity is usually expressed in units of
energy (e.g., joules m -2 day -1) or in units of dry organic
matter (e.g., kg m -2 year -1).
What is Productivity?
With the help of photosynthesis
Amount of energy or biomass

Gaining energy
Gaining biomass
Per unit area or time
Absorption
What is Gross Productivity?

What affects productivity?
1. Solar radiation
2. Temperature
3. CO2
4. H2O
5. Nutrients
6. Herbivory

The primary productivity
of an ecosystem depends on
a number of interrelated
factors, such as light
intensity, temperature,
nutrient availability,
water, and
mineral supply.
The most productive
ecosystems are
systems with high
temperatures, plenty of
water, and non-limiting
supplies of soil nitrogen.
Measuring Plant Productivity

Measuring Primary Productivity
1. Harvest method - measure biomass and
express as biomass per unit area per unit
time.
2. CO2 assimilation - measure CO2 uptake
in photosynthesis and release by
respiration.
3. O2 production - Measure O2 production
and consumption.

Measuring Primary Productivity
4. Radioisotope method - use C14 tracer in
photosynthesis.
5. Chlorophyll measurement - assumes a
correlation between amount of chlorophyll and
rate of photosynthesis.

Therefore…
• The least productive ecosystems are
those with limited heat and light
energy, limited water and limited
nutrients.
• The most productive ecosystems are
those with high temperatures, lots of
water, light and nutrients.

Biome Productivity
Estuaries
Swamps and marshes
Tropical rain forest
Temperate forest
Northern coniferous forest (taiga)
Savanna
Agricultural land
Woodland and shrubland
Temperate grassland
Lakes and streams
Continental shelf
Open ocean
Tundra (arctic and alpine)
Desert scrub
Extreme desert
800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600
Average net primary productivity (kcal/m2/yr)

Three years of satellite data on the earth’s GP.
LAND: high = dark green low = yellow
OCEAN: high = red low = blue

73%
Not used by humans
8%
Lost or degraded land
16%
Altered by human activity
3%
Used directly
Human use of
biomass
produced by
photosynthesis
(NPP).

0
16250
32500
48750
65000
Tropicalrainforest
Sw
am
ps
and
m
arshes
Estuaries
Savanna
Tem
perate
forest
B
orealforest
Tem
perate
grassland
Tundra/cold
desertC
oastalm
arine
O
pen
ocean
D
esert
The primary productivity of oceans is lower than that of terrestrial
ecosystems because the water reflects (or absorbs) much of the
light energy before it reaches and is utilized by the plant.
Ecosystem Productivity
kcal m-2y-1
kJ m-2y-1
Although the open ocean’s
productivity is low, the ocean
contributes a lot to the Earth’s total
production because of its large size.
Tropical rainforest also contributes a
lot because of its high productivity.

• In this way the plant accumulates energy and
this energy is called primary production.
• The rate at which this energy accumulates is
called primary productivity

Gaining energy
Gaining biomass
How much energy?

• Gross Productivity (GP) – is the total gain in energy or
biomass per unit time.
• This is sometimes shown as GPP – Gross Primary Productivity
• It is related to the total amount of chemical energy
incorporated into the producers.
• The producers use some of this energy during respiration and
energy needs which is eventually lost to the environment as
heat.
• It is measured per unit area per unit time.

Gross Productivity
Gross productivity is the total gain energy per unit time in
plants.
It is the biomass that could be gained by an organism
before any deduction.
But all organism have to respire to stay alive so some of
this energy is used up in staying alive instead of being
used to grow
Photosynthesis 2.2%
Reflection 3.0
Evaporation
(including transpiration and
heating of the surroundings
94.8
Total 100.0%

• Net productivity is the amount of energy you produce which can go on to
the next trophic level.
Net and Gross are being used in the same way as you can think of your
paycheck and the pay you take home after taxes.
Gross Productivity is all the energy/food that you make (all the glucose
that a plant creates fromphotosynthesis).
Net Productivity is the Gross Productivity - what the individual uses.
If a plant makes 10 molecules of glucose from photosynthesis but uses 4
molecules to grow, the net is 6 molecules that it has available.
This continues to decrease at each trophic level, if an insect eats the
plants 6 molecules of glucose, and uses 3 to breathe and move, when the
bird eats the insect, it only gets 3 molecules.

• Energy enters an ecosystem through
sunlight.(100%)
• Only 2% of the light energy falling on a
tree is captured and turned into chemical
energy (glucose) by photosynthesis.
• The rest is reflected, or just warms up the
tree as it is absorbed.
Gross Productivity (GP)

Gross Primary Production
• The total energy accumulated by producers is
called gross primary production, however,
since plants use some of this energy
themselves, it is not all available for the food
web

Gross Productivity on the Earth
• Varies across the surface of the earth
• Generally greatest productivity
– In shallow waters near continents
– Along coral reefs – abundant light, heat, nutrients
– Where upwelling currents bring nitrogen & phosphorous to the
surface
• Generally lowest
– In deserts & arid regions with lack of water but high
temperatures
– Open ocean lacking nutrients and sun only near the surface

Gaining energy
Gaining biomass
What is Gross Secondary Productivity ?

What is Net Productivity ?
Energy remaining after respiratory losses
Respiratory losses
Biomass remaining after respiratory losses
Net
Productivity

Net Productivity
• Net productivity is the remaining energy per unit time after
deductions due to respiration
• Net productivity is the amount of energy trapped in organic
matter during a specified interval at a given tropic level less
that lost by the respiration of the organisms at that level.

NET PRODUCTIVITY (NP)
• NP is the gain in energy or biomass per
unit time remaining after allowing for
respiratory loss.
• Organisms use some of the energy they
capture to keep themselves growing
and alive (metabolism).
• The energy used by organisms for
essential tasks is called RESPIRATORY
ENERGY, and eventually it is released
to the environment as heat.

What is Net Primary Productivity ?
After Respiratory losses
Gaining energy

Net Primary Productivity (NPP)
• The quantity of biomass potentially
available to consumers in an ecosystem.
• It is measured in unit of mass or energy per
unit area per unit time.
NPP = GP – respiration
(for both producers and consumers)

Net Primary Productivity on Earth
• Most NPP
– Estuaries, swamps, tropical rainforests
• Least NPP
– Open ocean, tundra, desert
• Open ocean has low NPP but its large area
gives it more NPP total than anywhere else

Ecosystem Type
Net Primary Productivity
(kilocalories/meter -2 /year)
Tropical Rain Forest 9000
Estuary 9000
Swamps and Marshes 9000
Savanna 3000
Deciduous Temperate Forest 6000
Boreal Forest 3500
Temperate Grassland 2000
Polar Tundra 600
Desert < 200
Average annual Net Primary Productivity of the Earth's major biomes.

After Respiratory losses
Gaining energy
Available energy goes to consumers
What is Net Secondary Productivity ?

What is Heterotrophic?
• An organism that cannot synthesize its own
food and is dependent on complex organic
substances for nutrition.
• Most bacteria and all animal,human and fungal
species are heterotrophic.

What is Secondary Productivity ?
Gaining biomass & absorption
Measuring

SECONDARY PRODUCTIVITY (SP)
• Biomass gained by
heterotrophic
organisms through
feeding and
absorption.
• Not all food eaten is
absorbed (assimilated)
into an animals body.
• Unassimilated food =
feces or droppings
SP = food eaten – fecal loss

Secondary production is the
amount of biomass at higher
trophic levels (the consumer
production).
It represents the amount of
chemical energy in
consumers’ food that is
converted to their own new
biomass.
Energy transfers between
producers and herbivores, and
between herbivores and
higher level consumers is
inefficient.
Secondary Production
Herbivores (1 consumers)...
Eaten by 2 consumers

In a food web you can
usually assume that:
• The energy input into
an organism = GP.
• The energy output to
the next trophic level =
NP.
• The difference between
GP and NP = R and/or
loss to decomposers.

Agricultural Land
• Highly modified, maintained ecosystems
• Goal is increasing NPP and biomass of crop
plants
• Add in water (irrigation), nutrients (fertilizer)
• Nitrogen and phosphorous are most often
limiting to crop growth

Plant material
consumed by
caterpillar
200 J
The percentage of energy
transferred from one trophic
level to the next varies
between 5% and 20% and is
called the ecological
efficiency.
An average figure of 10%
is often used. This ten
percent law states that the
total energy content of a
trophic level in an
ecosystem is only about
one-tenth that of the
preceding level.
Ecological Efficiency
100 J
Feces
33 J
Growth
67 J
Cellular
respiration

Productivity Calculations
Total Primary Production = (NPP)
Gross Primary Production
• Amount of light energy converted into chemical energy
by photosynthesis per unit time
– Joules / Meter2 / year
• Net Primary Production  GPP – R, or GPP – some
energy used for cell respiration in the primary producers.
• Standing crop = Total living material at a trophic level

Producers
• NPP = GPP – R
Consumers
• GSP = Food eaten – fecal losses
• NSP = change in mass over time
• NSP = GSP – R

Different methods of Measuring Primary Production
1. Measuring the aspects of photosynthesis
2. In marine we can use closed container measure O2
production, CO2 uptake over time
3. Must measure starting amount in environment then
amount added by producers
4. Use dissolved oxygen probe or carbon dioxide
sensor
5. Measure indirectly as biomass of plant material
produced over time (only accurate over long timer
periods)  this gives NPP

May 2012
• How to Measure Aquatic Primary Production
using the Light and Dark Bottle Method

TRANSPARENT BOTTLE(LIGHT BOTTLE)
OPAQUE BOTTLE(DARK BOTTLE)

Light and Dark Bottle Method – for
Aquatic Primary Production
• Changes in dissolved oxygen used to measure
GPP and NPP
• Measures respiration and photosynthesis
• Measure oxygen change in light and opaque
bottles
• Incubation period should range from 30
minutes to 24 hours
• Use B.O.D. bottles

• Take two sets of samples measure the initial
oxygen content in each (I)
• Light (L) and Dark (D) bottles are incubated in
sunlight for desired time period
• NPP = L – I
• GPP = L – D
• R = D – I

Sample Data
1. Write the equation for and calculate the GPP
2.Write the equation for and calculate the NPP
3. Write the equation for and calculate the Respiration

Evaluation
• Tough in unproductive waters or for short
incubation times
• Accuracy in these cases can be increased by
using radioactive isotopes C14 of carbon

Measuring Secondary Productivity
• Gross Secondary Production
– Measure the mass of food intake (I) by an organism
(best if controlled diet in lab)
– Measure mass of waste (W) (excrement, shedding,
etc.) produced
– GSP = I – W
• Net Secondary Production
– Measure organism’s starting mass (S) and ending
mass (E) for experiment duration
– NSP = E-S

Method evaluation
• GSP method difficult in natural conditions
• Even in lab hard to get exact masses for waste
• NSP method hard to document mass change in
organism unless it is over a long time period

What types of things effect productivity?
• What can we measure for an experiment?
– Effects of light exposure – strength, time, color, …
– Effects of temperature
– Differences between types of plants
– Differences between types of producers
– Effects of nutrient additions
– Effects of salinity

Other parameters to change
• Terrestrial vs. aquatic
• Oxygen, carbon dioxide
• Biomass
• B.O.D. bottles

How to Calculate GPP &NPP
• Calculate the values of both gross primary
• Productivity (GPP) and net primary
• Productivity (NPP) from given data.
NPP = GPP – R
where R = respiratory loss

How to Calculate GSP &NSP
• Calculate the values of both gross secondary
• Productivity (GSP) and net secondary
• Productivity (NSP) from given data.
• NSP = GSP – R
• GSP = food eaten – fecal loss
• where R = respiratory loss

What is POPULATION CURVE?
• The curve which is used to describe the
population of an particular animals in an
ecosystem is called POPULATION
CURVE

What are the main factors that affect
the growth of a population?
 The main factors that make
populations grow are births and
immigration.(The action of coming to
live permanently)
 The main factors that make
populations decrease are deaths and
emigration.(moving from one place)

What is Exponential growth?
• Exponential population growth is when
the birth rate is constant over a period of
time and isn't limited by food or disease

• Two types of population curve
• S Population Curve
• J Population Curve

TYPES OF POPULATION CURVE
.
• J-Shape curve is also known as- Exponential
curve occurs when there is no limit to
population size.

• S-Shape curve is also known as - Logistic
curve shows the effect of a limiting factor
• S-Sigmoid

What is S-Shaped Curve?
• In S - shaped or sigmoid growth the population
show an initial gradual increase in population
size in an ecosystem, followed by an
exponential increase and then a gradual decline
to near constant level.

• In population of an ecosystem which
factors determining the S shape curve?

The curve obtained by plotting growth and
time is called a growth curve. It is a typical
sigmoid or S- shaped curve.

What is J shaped?
• A curve on a graph that records the situation in
which the population density of an organism
increases rapidly but then stops abruptly as
environmental resistance

• The growth of population is measured as increase in
its size over a period of time and populations show
characteristic patterns of growth with time.
• These patterns are known as population growth
forms.

‘S’ Curves
• This is the type of graph that is almost always
seen in nature.
• As the energy resources become more scarce
the population size levels will decrease

‘J’ Curves
• In a ‘J’ curve shape, a population establishing
themselves in a new area will undergo rapid
exponential growth.
• This type of growth produces a J shaped growth
curve.
• If the resources of the new habitat were endless then
the population would continue to increase at this rate.

‘J’ Curves
• This type of population growth is rarely seen
in nature.
• Initially exponential growth will occur but
eventually the increase in numbers will not be
supported by the environment.
• .

300
Can hold 500
Carrying Capacity

• Area: 430 square kilometers
• Population :2500 rhinoceros
• It can hold up to 4000 Rhinoceros

CARRYING CAPACITY?
• For a given region, carrying capacity is the
maximum number of individuals of a given
species that an area's resources can sustain
indefinitely without significantly depleting or
degrading those resources.

• The carrying capacity (K) is the maximum
number of a species that the habitat can
hold.
• Carrying capacity will be change by the effect
of new disease, food resources & Water

Population Growth
Change in the size of a population
over time.

• POPULATION = a group of interbreeding
organisms (same species) that live in the same
place at the same time and compete for the same
resources.
• Resources = food, water, shelter, mates, and so on .
. .
• resources  pop. size
• resources  pop. size

Populations change in response to environmental stress
or changes in environmental conditions.
1. In size = # of individuals
2. Density = # of individual / specific space
3. Age distribution = proportions / age group
4. Dispersion
Clumped
(elephants)
Uniform
(creosote bush)
Random
(dandelions)

Every environment has a CARRYING
CAPACITY = the maximum number of
individuals of a given species that
can be sustained in a
given space.
2.0
1.5
1.0
.5
Numberofsheep(millions)
1800 1825 1850 1875 1900 1925
Year

Factors that affect carrying capacity:
1. Competition with/in and between species.
2. Natural and human caused catastrophes.
3. Immigration and emigration.
4. Seasonal fluctuations in food, water, shelter,
and nesting sites.

10 Rhino
5 rhino moving
5 rhino –Competition for the food
Emigration

10 Rhino
10 rhinos
Immigration

Bacteria population
8 1024
24 hours
later

LOGISTIC GROWTH involves initial exponential
growth and then there is a steady decrease in
growth as the population encounters environmental
resistance and approaches carrying capacity and
levels off.
“S or sigmoid”
population growth
curve
Time (t)
Populationsize(N)
K

Time (t)
Populationsize(N)
K
Exponential phase
Transitional phase
Plateau phase

2,000
1,500
Numberofreindeer
1910 1920 1930 1940 1950
Year
1,000
500

TWO TYPES OF SPECIES
• r-selected species
• K-selected species
• r-selected species live in variable or
unpredictable environments
• K-selected species live in fairly constant or
predictable environment

Examples of r-selected species
• Examples of r-selected species include pest organisms,
such as rodents, insects, Mosquitoes and Weeds(kind of
a plant).
• r-selected species thrive in disturbed habitats,
• Such as freshly burned grasslands
• Forest affected by natural calamities(flood or heavy rain)

Examples of K-selected species
• Examples of K-selected species
include birds, larger mammals (such
as elephants, horses, and primates), and
larger plants.

STABLE & UNSTABLE ENVIRONMENTS
• Organisms that live in stable environments
tend to make few, "expensive" offspring.
• Organisms that live in unstable
environments tend to make many, "cheap"
offspring.

How r/K is related to Ecology?
In ecology, r/K selection theory relates to the
selection of combinations of traits that trade
off the quantity and quality of offspring to
promote success in particular environments.
The terminology of r/K-selection was coined
by the ecologists Robert MacArthur and E. O.
Wilson based on their work on island
biogeography.

EXAMPLE
• Imagine that you are one of the many invertebrate
organisms which existed during the Cambrian or
one of their descendents living today.
• Maybe you live in a tide pool which is washed by
waves.
• A storm appears on the horizon.
• The waves increase in height.
• You feel yourself being dashed upon the rocks or
into the mouth of a much larger and predatory
animal.
• Finally, you begin to see your brothers and sisters
die, one by one, as the forces of nature change
your unpredictable environment.

• If you could design a "strategy" to overcome
the problems created by an unpredictable
environment, you would have two choices - go
with the flow or cut and run to a more
stable environment.

• Suppose you stayed. Then, one thing you could do
would be to increase the number of offspring.
• Make lots of cheap (requiring little energy investment)
offspring instead of a few expensive, complicated ones
(requiring a lot of energy investment).
• If you lose a lot of offspring to the unpredictable forces
of nature, you still have some left to live to reproductive
age and pass on your genes to future generations.
• Many invertebrates follow this strategy - lots of eggs are
produced and larvae are formed but only a few survive
to produce mature, reproductive adults. Many insects
and spiders also follow this strategy.

• Alternatively, you could adapt to a more stable
environment.
• If you could do that, you would find that it
would be worthwhile to make fewer, more
expensive offspring.
• These offspring would have all the bells and
whistles necessary to ensure a comfortable,
maximally productive life.
• Since the environment is relatively stable, your
risk of losing offspring to random
environmental factors is small. Large animals,
such as ourselves, follow this strategy.

Population Size
• In r-selected species, population size tends to
vary in time and recolonization occur into
unpopulated area frequently (pioneer species)
• In K-selected species, population size is
usually or near the carrying capacity and
colonization is infrequent

r Species Selection Factors
• Rapid Development
• High reproductive
• Early Reproduction
• Small Body Size
• Single Reproduction
• Many Small Offspring
• Short Life Span

K Species Selection Factors
• Slow Development
• Competitive Ability
• Delayed Reproduction
• Large Body Size
• Repeated Reproduction
• Few Large Offspring
• Long Life Span

What is difference between r &K?
K
1. Growth Pattern - large body, long juvenile period; Population grows
exponentially and then stabilizes around a max value
2. Population Size - smaller, but stable
3. Environment - stable, diverse ecology
4. Reproductive strategy - mate choice, pair bonds, large investment,
parental care, few offspring
5. Characteristics of offspring -They're born more dependent on the
parents and stay that way longer; later onset of repro maturity
• Examples - Elephants, humans, oak trees.

1. r
Growth Pattern - small body, rapid maturation;
population grows exponentially then crashes
2. Population Size - large, but rapid fluctuation
3. Environment - unstable, recently disrupted, low
diversity, low resources
4. Reproductive strategy - maximize number of
offspring, low parental investment, random mating
5. Characteristics of offspring - independent right
away, early reproductive maturity, large numbers
6. Examples - weeds, mosquitoes, mice

• In the scientific literature, r-selected
species are occasionally referred to as
"opportunistic", while K-selected species
are described as "equilibrium

RECAP
• What is r selected species? Example
• What is K selected species? Example
• How r/K species related to Ecology?
• What is Stable &unstable Environment
• r Species Selection Factors
• K Species Selection Factors

What is Density-Dependent Factors?
• A factor that affects the birth rate or
death rate of a population in a
different ways of limiting factor
with the population density.

Density Dependent Factors
• Increasing in population size reduces the
available resources of the limiting population
growth.
• A density-dependent factor intensifies as the
population size increases, affecting each
individual more strongly.
• Population growth declines because of death
rate increase, birth rate decrease or both.

• Density-dependent limiting factors include:
1. Competition
2. Predation
3. Disease

WHAT IS DENSITY INDEPENDENT FACTORS?
• Any factor that limiting the entire size of a
population is called Density Independent
Factors.
• An example of such a factor is an earthquake,
which will kill all members of the population
regardless of whether the population is small
or large.

DENSITY INDEPENDENT FACTORS = affect a populations’
size regardless of its population density.
1. Weather
2. Earthquakes
3. Floods
4. Fires

DENSITY DEPENDENT FACTORS = affect a populations’ size
depending on its population density.
1. Predation
2. Disease
3. Availability of food and water
4. Space
Negative Feedback!!

Population Dynamics
Factors that tend to increase or decrease
the size of a population.

The population size of a species in a given space at a
given time is determined by the interplay between
BIOTIC POTENTIAL and ENVIRONMENTAL
RESISTANCE.
Biotic potential = growth rate with unlimited resources.
Environmental resistance = all the factors acting jointly
to limit population growth.

POPULATION SIZE
Growth factors
(biotic potential)
Favorable light
Favorable temperature
Favorable chemical environment
(optimal level of critical nutrients)
Abiotic
Biotic
High reproductive rate
Generalized niche
Adequate food supply
Suitable habitat
Ability to compete for resources
Ability to hide from or defend
against predators
Ability to resist diseases and parasites
Ability to migrate and live in other
habitats
Ability to adapt to environmental
change
Decrease factors
(environmental resistance)
Too much or too little light
Temperature too high or too low
Unfavorable chemical environment
(too much or too little of critical
nutrients)
Abiotic
Biotic
Low reproductive rate
Specialized niche
Inadequate food supply
Unsuitable or destroyed habitat
Too many competitors
Insufficient ability to hide from or defend
against predators
Inability to resist diseases and parasites
Inability to migrate and live in other
habitats
Inability to adapt to environmental
change

Four variables change population size:
1. NATALITY = birth rate
2. MORTALITY = death rate
3. IMMIGRATION = rate of organisms moving in
4. EMIGRATION = rate of organisms moving out

Numberofindividuals
Time
Carrying capacity
K species;
experience
K selection
r species;
experience
r selection
K
REPRODUCTIVE STRATEGIES

Opportunistic or r-Selected Species
cockroach dandelion
1. Many small offspring
2. Little or no parental care and protection of offspring
3. Early reproductive age
4. Most offspring die before reaching reproductive age
5. Small adults
6. Adapted to unstable climate and environmental
7. conditions
8. High population growth rate (r)
9. Population size fluctuates wildly above and below
10. carrying capacity (K)
11. Generalist niche
12. Low ability to compete
13. Early successional species

1. Fewer, larger offspring
2. High parental care and protection of offspring
3. Later reproductive age
4. Most offspring survive to reproductive age
5. Larger adults
6. Adapted to stable climate and environmental
7. conditions
8. Lower population growth rate (r)
9. Population size fairly stable and usually close
10. to carrying capacity (K)
11. Specialist niche
12. High ability to compete
13. Late successional species
elephant saguaro
Competitor or K-Selected Species

Population density affects
population growth.

INTERNAL FACTORS = might include density-
dependent fertility or size of breeding territory.
EXTERNAL FACTORS = might include predation and
disease.

Species interactions influence population growth and carrying
capacity = SYMBIOSIS
Competition for resources.
High
Low
Relativepopulationdensity
0 2 4 6 8 10 12 14 16 18
Days
Each species grown alone
Paramecium
aurelia
Paramecium
caudatum
High
Low
Relativepopulationdensity
0 2 4 6 8 10 12 14 16 18
Days
Both species grown together
Paramecium
aurelia
Paramecium
caudatum

Mutualism
Oxpeckers and black rhinoceros Clown fish and sea anemone

Cleaning station
Sabertooth blenny
Cleaner blenny

Survivorship curves
• A survivorship curve is a graph showing the
number or proportion of individuals surviving
at each age for a given species or group (e.g.
males/females).

• There are three generalized types of
survivorship curve, which are simply
referred to as
• Type I, Type II and Type III curves.

TYPE 1
• A Convex curve
• Type I survivorship curves are characterized
by high survival in early and middle life,
followed by a rapid decline in survivorship in
later life.
• Humans,Red deers &Elephants are one of the
species that show this pattern of survivorship.

TYPE II
• A straight line
• Type II curves are an intermediate between Type I
and III, where roughly constant mortality rate is
experienced regardless of age.
• Some birds & reptiles follow this pattern of
survival.

Type III
• A concave curve
• In Type III curves, the greatest mortality is
experienced early on in life, with relatively
low rates of death for those surviving this
bottleneck.
• This type of curve is characteristic of species
that produce a large number of offspring
• Ex: Oysters, Rat & Turtles

Mortality, Survivorship, &
Competition
• In r-selected species mortality is often catastrophic
and subject to density independent limiting factors.
• Survivorship is low early in life but increases for
those individuals surviving (Type III). Competition
lax.
• In K-selected species mortality is subject to density
dependent limiting factors Survivorship is high
throughout life until late in life (Type I). Competition
keen.

What are Lichens?
• Lichens are composite organisms
consisting of a fungus and
a photosynthetic partner growing together
in a symbiotic relationship.

What are Mosses?
• Mosses are a botanical division (phylum) of
small, soft plants that are typically 1–10 cm
(0.4–4 in) tall

In ecology what is succession?
• Succession is the process by which a habitat
changes over time as different plants get
established.
• This process can occur from bare rock up to an
old-growth forest, and can get reset by a
disturbance such as fire.
• The path of succession varies from one habitat
type to another, but the general idea goes like this:
Bare rock ---> Lichens --> Mosses --> Grasses &
Forbs --> Brush --> Deciduous hardwood forest --
> Mixed deciduous-coniferous forest -->
Coniferous forest --> Old growth coniferous forest

What is Ecological succession?
• Ecological succession, a fundamental concept
in ecology, refers to more or less predictable
and orderly changes in the composition or
structure of an ecological community.

Types of succession
Two types of Succession
• Primary succession
• Secondary succession

Primary Succession
• Primary succession is the series of community
changes which occur on an entirely new
habitat which has never been colonized before.
• Examples of such habitats would include
newly exposed or deposited surfaces, such as
landslips, elevated sand banks and dunes,
quarried rock faces.
• Stages will take place in which an initial or
'pioneer' community will gradually develop
through a number of different communities
into a 'climax' community, which is the final
stage

the succession of a pond ecosystem to a meadow over 250
years.

Coastal Sand Dunes
An Example of Primary Succession

• Primary succession is the gradual growth of
organisms in an area that was previously bare,
such as rock.
• For example lichens, mosses, and ferns will
first appear on bare rock.
• In primary succession pioneer species like
mosses, lichen, algae and fungus as well as
other abiotic factors like wind and water start
to "normalize" the habitat.

What is Secondary succession?
• Secondary succession is the series of
community changes which take place on a
previously colonized, but disturbed or damaged
habitat.
• Examples include areas which have been
cleared of existing vegetation (such as after tree-
felling in a woodland) and destructive events
such as forest fires.

• Secondary succession can proceed much
faster because the soil has already been
prepared by the previous community

• Secondary succession is usually much quicker
than primary succession for the following
reasons:
• There is already an existing seed bank of
suitable plants in the soil.
• Root systems undisturbed in the soil, stumps
and other plant parts from previously existing
plants can rapidly regenerate.
• The fertility and structure of the soil has also
already been substantially modified by
previous organisms to make it more suitable
for growth and colonization.

• The mature stage of succession in a particular area, in
which all organisms and non living factors are in
balance.
• Terrestrial communities of organisms move through a
series of stages from bare earth or rock to forests of
mature trees.
• This last stage is described as the "climax" because it is
thought that, if left undisturbed, communities can
remain in this stage in perpetuity.
• However, more recent studies suggest that climax may
be only one part of a continuous cycle of successional
stages in these communities.

Differences between pioneer and climax
communities
Pioneer Community Climax Community
Unfavorable environment favorable environment
biomass increases quickly biomass is generally stable
energy consumption inefficient energy consumption efficient
some nutrient loss Nutrient cycling and recycling
r - strategists K - strategists
low species diversity, habitat
diversity, genetic diversity
high species diversity, habitat
diversity, genetic diversity

The following charts summarize the major trends
as the ecosystem undergoes succession.
Ecosystem
characteristic
Trends in ecological succession
Food chains Simple food chains becoming more complex food webs
Relative Species
abundance
Changes rapidly first, changes slower in the later stages.
Total biomass Increasing
Humus (non-
living organic
matter)
Increasing
Species
diversity
Low diversity in the early stages, then increasing in the
intermediate stages and then stabilizing in the final stages
as an equilibrium is approached

Productivity
Ecosystem characteristic Trends in ecological
succession
Gross productivity (GP) Increasing during early
stages of primary
succession then little or no
increase during final stages
of secondary succession
Net productivity (NP) Decreasing
Respiration (R) Increasing

Mineral and Nutrient cycles
Ecosystem characteristic Trends in ecological succession
Mineral cycles Becomes more self-contained
in later stages
Nutrient recycling Increases in later stages

Chapter :
Topic : Transfer and Transformation
of Materials in Cycle in Eco system

• The cyclic transformation of chemicals through
interacting biological, geological and chemical
processes.
• Natural processes that recycle nutrients in
various chemical forms from the environment,
to organisms, and then back to the environment
• Ex: Carbon, oxygen, nitrogen, phosphorus, and
hydrologic cycles.
What is Biogeochemical cycle?

• The biogeochemical cycles of all elements
used by life have both an organic and an
inorganic phase.
• This cycling involves the decomposition of
organic matter back into inorganic nutrients

What is Carbon Cycle?
• The process by which carbon is taken up by
plants and animals and returned to the
environment in a continuous cycle.
• The carbon cycle is the biogeochemical cycle
by which carbon is exchanged among the
biosphere, geosphere, hydrosphere, and
atmosphere of the Earth.

Carbon is stored on our planet in the following
major sinks
1. As organic molecules in living and dead
organisms found in the biosphere;
2. As the gas carbon dioxide in the atmosphere;
3. As organic matter in soils;
4. In the lithosphere as fossil fuels and
sedimentary rock deposits such as limestone,
5. In the oceans as dissolved atmospheric carbon
dioxide and as calcium carbonate shells in
marine organisms.

Syllabus
2.1 Structure
2.2 Measuring abiotic components of the
system
2.3 Measuring biotic components of the system
2.4 Biomes
2.5 Function-Not included biogeochemical
cycles
2.6 Changes

What is Nitrogen cycle ?
• A process in which atmospheric nitrogen enters
the soil and becomes part of living organisms,
and then returns to the atmosphere.
• Cyclic movement of nitrogen in different
chemical forms from the environment, to
organisms, and then back to the environment.

• Earth's atmosphere is approximately 78-80%
nitrogen making it the largest pool of nitrogen.
• Most plants can only take up nitrogen in two
solid forms: ammonium ion and the nitrate
ion .
• Most plants obtain the nitrogen they need as
inorganic nitrate from the soil solution.
• Animals receive the required nitrogen they
need for metabolism, growth, and
reproduction

3 PROCESS OF NITROGEN IN THE
EARTH
• Nitrogen fixation----nitorgen+O2+CO2+H2
• Nitrification---- conversion of ammonia to nitrate
• Denitrification-- nitrate becomes molecular(GAS)
nitrogen Bacteria

Ammonium Nitrate
Nitrogen dioxide
Nitrite bacteria (present in the soil)
Nitrate bacteria
Nitrate
Directly-
Bacteria present
in plant roots
starts active on
lightening
Convert into
gas with help
of bacteria
Nitrogen
fixation
Denitrification

What is Symbiotic bacteria
• Symbiotic bacteria are bacteria living
in symbiosis with another organism
or each other.

• The conversion of atmospheric nitrogen into
compounds, such as ammonia, by natural agencies .
This is known as nitrogen fixation
• Some fixation occurs in lightning strikes, but most
fixation is done by free-living or symbiotic bacteria.
• These bacteria have the nitrogenase enzyme that
combines gaseous nitrogen with hydrogen to produce
ammonia.
What is Nitrogen fixation?

What is Nitrification?
• The conversion of ammonia (NH3) to nitrate
(NO3-) is called NITRIFICATION
• Degradation of ammonia to nitrite is usually the
rate limiting step of nitrification.
• Nitrification is an important step in the nitrogen
cycle in soil

What is Denitrification?
• The process by which a nitrate becomes
molecular nitrogen, especially by the action of
bacteria.
• The process by which nitrogen, is converted to
a gaseous form and lost from the soil or water
column.
• The reduction of nitrate nitrogen to nitrogen
gas.

Nitrate
Nitrogen dioxide
Ammonium Nitrate
Nitrogen

• Almost all of the nitrogen found in any
terrestrial ecosystem originally came from the
atmosphere.
• Significant amounts enter the soil in rainfall or
through the effects of lightning.
• The majority, however, is biochemically fixed
within the soil by specialized micro-organisms
like bacteria, actinomycetes, and
cyanobacteria.

• The cycle of water movement from the atmosphere to the earth
and back to the atmosphere through condensation, precipitation,
evaporation, and transpiration is called WATER CYCLE
• The continual cycle of water between the land, the ocean and
the atmosphere.
• The water cycle, also known as the hydrologic cycle, describes
the continuous movement of water on, above and below the
surface of the Earth.
What is Water Cycle ?

• The four stages in this process are:
Evaporation
Condensation
Precipitation
Collection
.

Evaporation
• This is the first stage of the water cycle.
• The Sun's rays heat the water on the surface of
the earth in rivers, oceans and lakes.
• This makes the water change into water vapour.

Condensation :
After evaporation, condensation occurs.
 Water vapor in the air gets cold and changes
back into liquid, forming clouds
 The process that causes these changes is called
condensation.

• Precipitation :
Precipitation occurs when so much water has condensed that
the air cannot hold it anymore. The clouds get heavy and
water falls back to the earth in the form of rain
• Collection
After precipitation comes the stage of collection. The
raindrops fall back into the lakes, rivers and oceans or are
absorbed by the land. This process by which rainwater
gathers on earth is called collection.

What is ZONATION?
• Zonation – The arrangement or patterning of plant
communities or ecosystems into bands in response to
change, over a distance, in some environmental
factor.
• The main biomes display zonation in relation to
latitude and climate. Plant communities may also
display zonation with altitude on a mountain, or
around the edge of a pond in relation to soil moisture.

Heating of solids, sunlight and shade in different altitudinal zones
(North hemisphere)

What is Environmental gradient?
• An environmental gradient is a gradual
change in abiotic factors through space (or
time). Environmental gradients can be related
to factors such as altitude, temperature, depth,
ocean proximity and soil humidity.

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