Biotic and Abiotic Factors
Biotic 1. Food – both quantity and
quality of food are important.
2. Predators – refer back to predator prey relationships.
3. Competitors – other organisms may require the same resources from an environment.
4. Parasites – may cause disease and slow down the growth of an organism.
Abiotic 1. Temperature – higher
temperatures speed up enzyme-catalyzed reactions and increase growth.
2. Oxygen Availability – affect the rate of energy production by respiration.
3. Light Availability – for photosynthesis and breeding cycles in animals and plants.
4. Toxins and pollutants – tissue growth may be reduced.
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2.2 Measuring Abiotic Components of the System
2.3 Measuring Biotic Components of the System
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Ecosystem 2
Setting up stage quadrats of 100m2 in the meadow area of the ecological gradient
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Ecosystem 3
Setting up group quadrats of 1m2
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Ecosystem 4
Setting up sampling quadrats of 0.1m2 in the meadow
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Ecosystem 5
Using the light meter in the forest group quadrat of 1m2
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Soil Temperature
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Taking a soil sample with a soil borer (auger) in the forest section of the
gradient
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Results of soil borer sample, Chemical analysis of the soil can be seen
in the background
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Ecosystem 9
Testing the meadow area for pH, phosphates, nitrates and potassium
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Collecting samples in Ziploc bags for analysis back in the lab
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Taking observations in the forest Notice the absence of plant growth on the
forest floor
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Chemical testing in the forest
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Insect sampling with net in the meadow
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Setting up 0.1m2 sampling quadrats for biomass analysis
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Next Chapter…..
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Chapter : 2.5.2
Topic : Photosynthesis & Respiration
in Energy Transformation
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Figure 10.1 Photoautotrophs
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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
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Figure 10.2 Focusing in on the location of photosynthesis in a plant
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Energy Processes
• Photosynthesis (Green Plants)
sunlight +water + carbon dioxide oxygen + sugars
• Respiration (All living things)
oxygen + sugars ATP +water + carbon dioxide
• ATP is molecular energy storage
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Producers • Make their own food - photoautotrophs,
chemoautotrophs
• Convert inorganic materials into organic
compounds
• Transform energy into a form usable by living
organisms
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Photosynthesis
• Inputs – sunlight, carbon dioxide, water
• Outputs – sugars, oxygen
• Transformations – radiant energy into chemical
energy, inorganic carbon into organic carbon
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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
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• 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.
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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
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• carbon dioxide + water chlorophyll →→→→→→→→ light energy sugar (glucose) + oxygen
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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.
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RECAP
• What is photosynthesis?
• What is RESPIRATION?
• Output of Photosynthesis
• Output of Respiration
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2.5.5-- Define the terms gross productivity, net
productivity, primary productivity and
secondary productivity.
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2.5.5-.7 Productivity
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• 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
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What is Productivity?
• The rate at which producers convert light energy into chemical energy is called primary productivity.
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• PRODUCTIVITY is production per unit time.
Energy per unit area per unit time (J m-2 yr-1)
Or
Biomass added per unit area per unit time (g m-2 yr-1)
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The energy entering ecosystems is
fixed by producers in photosynthesis.
Gross primary production (GPP)
is the total energy fixed by a plant
through photosynthesis.
Net primary production (NPP) is
theGPP minus the energy required
by the plant for respiration.
It represents the amount of stored
chemical energy that will be
available to consumers in an
ecosystem.
Primary Production
Grassland: high productivity
Grass biomass available to consumers
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Primary Productivity
The term used to describe the amount of
organic matter an ecosystem produces from
solar energy within a given area during a given
period of time.
Primary productivity simply defined is the
production of new plant material. In the oceans
this new plant material is phytoplankton
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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
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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.
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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
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What is Gross Productivity?
• 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.
• The remaining energy is available to the herbivores and is known as net primary productivity (NPP)
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Gross Productivity
• 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
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GROSS PRIMARY PRODUCTIVITY (GPP)
• GPP is the quantity of matter produced, or solar
energy fixed, by photosynthesis in green plants
• It is measured per unit area per unit time.
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• Energy enters an ecosystem through
sunlight.
• 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.
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Ocean Area vs Productivity
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Effects of Depth
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Net Productivity • Net productivity is the gain in energy per unit time that
remains 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.
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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.
• Plants have to use some of the energy they
capture to keep themselves growing and
alive (metabolism).
NPP = GPP - respiration
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NET PRODUCTIVITY (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.
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NP = GP – respiration (for both producers and consumers)
When energy is released from ATP it is lost
as heat. (2nd Law of Thermodynamics)
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What is Net Productivity?
• Some of GPP used to stay alive, grow and
reproduce
• NPP is what’s left
• 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
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JANUARY-FEBRAURY SUMMATIVE
• Date : 6th February, Wednesday
• Syllabus-The Ecosystem-
• Unit 2.5-Function
• Marks-45
• Time :1 hour
• Paper 1
• Formative:
• Holiday homework
• Worksheet
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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
• Despite modification NPP in agricultural land is less than many other ecosystems
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RECAP
• What is Productivity?
• What is GPP?
• What is NPP?
• How to measure the GROSS PRIMARY
PRODUCTIVITY
• How to measure the primary productivity
• What is Net Productivity?
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Secondary Productivity
The rate at which herbivores produce new
biomass through growth and reproduction.
As a rule of thumb, only 10 percent of plant
matter is converted to herbivore tissue.
The remainder is either not ingested, not
digested (and thus passed through an animal to
be eliminated as feces) or released as heat.
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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
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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.
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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
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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
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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.
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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.
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What affects productivity?
1. Solar radiation
2. Temperature
3. CO2
4. H2O
5. Nutrients
6. Herbivory
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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.
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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)
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Three years of satellite data on the earth’s GP.
LAND: high = dark green low = yellow
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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).
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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.
• Represents the energy storage available for the whole community of consumers
• Standing crop = Total living material at a trophic level
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Producers
• NPP = GPP – R
Consumers
• GSP = Food eaten – fecal losses
• NSP = change in mass over time
• NSP = GSP – R
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Measuring Primary Production
– Measure aspects of photosynthesis
– In closed container measure O2 production, CO2
uptake over time
– Must measure starting amount in environment then
amount added by producers
– Use dissolved oxygen probe or carbon dioxide
sensor
– Measure indirectly as biomass of plant material
produced over time (only accurate over long timer
periods) this gives NPP
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• Measuring Aquatic Primary Production using
the Light and Dark Bottle Method
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TRANSPARENT BOTTLE(LIGHT BOTTLE)
OPAQUE BOTTLE(DARK BOTTLE)
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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
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• 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
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Sample Data
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Method evaluation
• Tough in unproductive waters or for short
incubation times
• Accuracy in these cases can be increased by
using radioactive isotopes C14 of carbon
• Radioactivity measured with scintillation
counter
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Can use satellite imaging: Nutrient rich waters of the north Atlantic
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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
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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
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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
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Other parameters to change
• Terrestrial vs. aquatic
• Oxygen, carbon dioxide
• Biomass
• B.O.D. bottles
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GPP estimates
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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
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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
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March summative
• Date :15 March,2013
• Format: Paper 2
• Total Marks-65
• Syallabus:Ecosystem
• Time :3:30pm -5:30pm
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March Formative
• Collect four different types of feather and
name it.
Marks will be given based on
• Presentation
• Naming the bird
• Decoration of the chart
• Submission on Date
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2.6.1-.2 Populations
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Topic -2.6
CHANGES
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What is POPULATION CURVE?
• The curve which is use to describe the
population of an particular animals in an
ecosystem is called POPULATION
CURVE
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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)
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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
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• Two types of population curve
• S Population Curve
• J Population Curve
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TYPES OF POPULATION CURVE
• Two modes of population growth.
• J-Shape curve is also known as- Exponential
curve occurs when there is no limit to
population size.
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• S-Shape curve is also known as - Logistic
curve shows the effect of a limiting factor
• S-Sigmoid
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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.
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• In population of an ecosystem which
factors determining the S shape curve?
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The curve obtained by plotting growth and
time is called a growth curve. It is a typical
sigmoid or S- shaped curve.
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What is J shaped? • A curve on a graph that records the situation in which, in a new environment, the population density of an organism increases rapidly but then stops abruptly as environmental resistance
• It may be summarized mathematically as:
I. dN/dt = rN (with a definite limit on N)
II. where N is the number of individuals in the population, t is time, and
III. r is a constant representing the rate of increase for the organism concerned.
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• 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
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RECAP • What is POPULATION CURVE?
• What are the main factors that affect
the growth of a population?
• What are the types of population curve?
• What is S shaped?
• What is J shaped?
• What are the different stages of S shaped
curve?
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• Area: 430 square kilometers
• Population :2500 rhinoceros
• It can hold up to 4000 Rhinoceros
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CARRYING CAPACITY
• The population that can be supported
indefinitely by an ecosystem without
destroying that ecosystem
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What is Carrying Capacity?
• The carrying capacity (K) is the maximum
number of a species that the habitat can hold.
• Once the carrying capacity is reached, unless the
environmental resistance is changed, e.g. by a new
disease, the size of the population will only fluctuate
slightly.
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‘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 off at the carrying
capacity (K).
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‘J’ Curves
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‘J’ Curves
• ‘J’ curve example, 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.
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‘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.
• .
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March summative
• Date :15 March,2013
• Format: Paper 2
• Total Marks-65
• Syallabus:Ecosystem
• Time :3:30pm -5:30pm
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March Formative
• Collect four different types of feather and
name it.
Marks will be given based on
• Presentation
• Naming the bird
• Decoration of the chart
• Submission on Date
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RECAP
• What is CARRYING CAPACITY?
• Example of Carrying capacity
• Which type of curve is common in nature?
Why?
• Why J curve is not common in the nature?
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Population Growth
Change in the size of a population over time.
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• 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
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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)
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No population can grow indefinitely!
Every environment has a CARRYING
CAPACITY = the maximum number of
individuals of a given species that
can be sustained indefinitely in
a given space. 2.0
1.5
1.0
.5
Nu
mb
er
of
she
ep
(m
illio
ns)
1800 1825 1850 1875 1900 1925
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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.
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A population that has few if any resource
limitations grows exponentially.
EXPONENTIAL GROWTH starts out slowly and
then proceeds faster and faster as the
population increases.
Time (t)
Po
pu
lati
on
siz
e (
N) “J” population
growth curve
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Bacteria population
8 1024
24 hours
later
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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)
Po
pu
lati
on
siz
e (
N)
K
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Time (t)
Po
pu
lati
on
siz
e (
N)
K
Exponential phase
Transitional phase
Plateau phase
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Kaibab Plateau
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2,000
1,500
Nu
mb
er
of
rein
de
er
1910 1920 1930 1940 1950
Year
1,000
500
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Kaibab Plateau
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March summative
• Date :4th April,2013
• Format: Paper 2
• Total Marks-40
• Syallabus:Ecosystem
• Two Essay Type Questions
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March Formative
• Collect four different types of feather and
name it.
Marks will be given based on
• Presentation
• Naming the bird
• Decoration of the chart
• Submission on Date
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2.6.1- Population Dynamics
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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
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Examples of r-selected species
• Examples of r-selected species include pest organisms,
such as rodents, insects, Mosquitoes and Weeds.
• r-selected species thrive in disturbed habitats, such as
freshly burned grasslands or forests characterized by
canopies that open abruptly, such as when a forest’s
tallest trees have been knocked down by a windstorm
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Examples of K-selected species
• Examples of K-selected species
include birds, larger mammals (such
as elephants, horses, and primates), and
larger plants.
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K & R STRAEGIST
• Species of organism that uses a survival and
reproductive 'strategy' characterised by low
mortality, longer life and with populations
approaching the carrying capacity of the
environment, controlled by density-dependent
factors.
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• What is Density-Dependent Factors?
• A limiting factor that depends on population size is called a density-dependent limiting factor.
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What is Density Dependent Factors
• Increasing population size reduces available resources limiting population growth.
• In restricting 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.
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• Density-dependent limiting factors include:
1. Competition
2. Predation
3. Parasitism
4. Disease
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• Examples of density-
dependent limiting factors include:
1. Unusual weather
2. Natural disasters
3. Seasonal cycles
4. Certain human activities—such as
damming rivers and clear-cutting forests
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How this 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.
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Robert MacArthur
E. O. Wilson
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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.
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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.
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• 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.
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• 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.
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• 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.
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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.
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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 at or near the carrying capacity and
colonization is infrequent (keystone species in
climax communities)
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r Species Selection Factors
• Rapid Development
• High r = or net reproductive rate
• Early Reproduction
• Small Body Size
• Single Reproduction
• Many Small Offspring
• Short Life Span
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K Species Selection Factors
• Slow Development
• Competitive Ability
• Delayed Reproduction
• Large Body Size
• Repeated Reproduction
• Few Large Offspring
• Long Life Span
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March summative
• Date :4th April,2013
• Format: Paper 2
• Total Marks-40
• Syallabus:Ecosystem
• Two Essay Type Questions
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RECAP
• What is r selected species? Example
• What is K selected species? Example
• What is Density-Dependent Factors?
• Factors which includes Density-dependent
limiting are…
• How r/K species related to Ecology?
• What is Stable &unstable Environment
• r Species Selection Factors
• K Species Selection Factors
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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.
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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
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• In the scientific literature, r-selected species are occasionally referred to as "opportunistic", while K-selected species are described as "equilibrium
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Population Dynamics
Factors that tend to increase or decrease the size of a population.
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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.
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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
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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
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Nu
mb
er
of
ind
ivid
ual
s
Time
Carrying capacity
K species; experience K selection
r species; experience r selection
K
REPRODUCTIVE STRATEGIES
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Opportunistic or r-Selected Species
cockroach dandelion
Many small offspring Little or no parental care and protection of offspring Early reproductive age Most offspring die before reaching reproductive age Small adults Adapted to unstable climate and environmental conditions High population growth rate (r) Population size fluctuates wildly above and below carrying capacity (K) Generalist niche Low ability to compete Early successional species
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Fewer, larger offspring High parental care and protection of offspring Later reproductive age Most offspring survive to reproductive age Larger adults Adapted to stable climate and environmental conditions Lower population growth rate (r) Population size fairly stable and usually close to carrying capacity (K) Specialist niche High ability to compete Late successional species
elephant saguaro
Competitor or K-Selected Species
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SURVIVORSHIP CURVES
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Population density affects population growth.
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DENSITY INDEPENDENT FACTORS = affect a populations’
size regardless of its population density.
1. Weather
2. Earthquakes
3. Floods
4. Fires
. . . Natural disasters
R-strategists populations are most affected by these.
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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!!
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INTERNAL FACTORS = might include density-
dependent fertility or size of breeding territory.
EXTERNAL FACTORS = might include predation and
disease.
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Species interactions influence population growth and carrying
capacity = SYMBIOSIS
Competition for resources.
High
Low
Re
lati
ve p
op
ula
tio
n d
en
sity
0 2 4 6 8 10 12 14 16 18
Days
Each species grown alone
Paramecium aurelia
Paramecium caudatum
High
Low
Re
lati
ve p
op
ula
tio
n d
en
sity
0 2 4 6 8 10 12 14 16 18
Days
Both species grown together
Paramecium aurelia
Paramecium caudatum
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Resource Portioning
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PREDATION
PREY
POPULATION
PREDATOR
POPULATION
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Span worm Bombardier beetle
Viceroy butterfly mimics monarch butterfly
Foul-tasting monarch butterfly
Poison dart frog When touched, the snake caterpillar changes shape to look like the head of a snake
Wandering leaf insect
Hind wings of io moth resemble eyes of a much larger animal
Avoiding predators
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Parasitism
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Mutualism
Oxpeckers and black rhinoceros Clown fish and sea anemone
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Shark and ramora
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Cleaning station
Sabertooth blenny
Cleaner blenny
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Commensalism
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Herbivory
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Chapter : 2.5.4
Topic : Transfer and Transformation
of Materials in Cycle in Eco system
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• 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?
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• 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
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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.
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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.
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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.
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• 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
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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
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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
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• Conversion of nitrogen into compounds is essential by combining with carbon, hydrogen and oxygen before it can be absorbed by the plants. 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?
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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
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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.
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Nitrate
Nitrogen dioxide
Ammonium Nitrate
Nitrogen
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actinomycetes
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cyanobacteria
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• 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.
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• 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 ?
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• The four stages in this process are:
Evaporation
Condensation
Precipitation
Collection
.
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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.
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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.
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• 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.
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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.
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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.
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School Director
Principal
Coordinator
Teacher
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Heating of solids, sunlight and shade in different altitudinal zones
(North hemisphere)
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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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Changes in the distribution of animals with
elevation on a typical mountain in Kenya. Another
example of Zonation
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• In population of an ecosystem which factors
determining the J shape curve?
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Estimated Net Productivity of Certain Ecosystems (in
kilocalories/m2/year)
Temperate deciduous forest 5,000
Tropical rain forest 15,000
Tall-grass prairie 2,000
Desert 500
Coastal marsh 12,000
Ocean close to shore 2,500
Open ocean 800
Clear (oligotrophic) lake 800
Lake in advanced state of
eutrophication 2,400
Silver Springs, Florida 8,800
Field of alfalfa (lucerne) 15,000
Corn (maize) field, U.S. 4,500
Rice paddies, Japan 5,500
Lawn, Washington, D.C. 6,800
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2.6 CHANGES
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The series of changes in an ecological community
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• Lichens re composite organisms consisting of a fungus and a photosynthetic partner growing together in a symbiotic relationship.
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• Mosses are a botanical division (phylum) of
small, soft plants that are typically 1–10 cm
(0.4–4 in) tall
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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
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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.
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Types of succession
Two types of Succession • Primary succession
• Secondary succession
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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, volcanic lava and debris, 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
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Coastal Sand Dunes An Example of Primary Succession
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• 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.
• This creating conditions nearer optimum for
vascular plant growth
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the succession of a pond ecosystem to a meadow over 250 years.
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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 fires.
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• Secondary succession can proceed much faster because the soil has already been prepared by the previous community
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• 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.
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• 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.
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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
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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
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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
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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
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1.World Environment Day is observed
on which date :
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2.In which year Project Tiger was
introduced in India
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3.Which State in India having the
highest percentage of forests?
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4.Earth day is observed on which
date
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5.Branch of Biology which is concerned
with the inter-relationship between plants
and animals is called :
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6.Which is the first state to implement the
path-breaking proposal that environment
should be included as a separate subject in
schools?
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7.Name the National Marine
animal of India?
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8.Which popular brand takes its name
from a particular species of deer native
to South Africa?
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9.Which comic character cannot
stand trees being cut down?
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• 10.Which ancient Indian text contains
rules and regulations on how to run a
protected forest or a ‘abhayaranya’?
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1.World Environment Day is observed
on which date :
June 5
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2.In which year Project Tiger was
introduced in India
1973
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3.Which State in India having the
highest percentage of forests?
Mizoram
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4. Earth day is observed on which
date
April 22
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5.Branch of Biology which is concerned
with the inter-relationship between plants
and animals is called :
Ecology
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6.Which is the first state to implement the
path-breaking proposal that environment
should be included as a separate subject in
schools?
Maharashtra
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7.Name the National Marine
animal of India?
Gangetic Dolphin
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8.Which popular brand takes its name
from a particular species of deer native
to South Africa?
Reebok
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9.Which comic character cannot
stand trees being cut down?
Dogmatix of Asterix
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• 10.Which ancient Indian text contains
rules and regulations on how to run a
protected forest or a ‘abhayaranya’?
Kautilya’s Arthashastra
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• This tree was supposedly brought to India from Sri Lanka by Hanuman when he was carrying messages from Sita. He felt so delighted by it that he threw the seeds on what is presently Maharashtra. Which tree?
• The Mango
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