IBESAS Topics 1-4 full syllabus
review
• 1.1.1: Outline the concept and characteristics of
a system
• 1.1.2: Apply the systems concept on a range of
scales
• 1.1.3: Define the terms open system, closed
system, isolated system
• 1.1.4: Describe how the first and second laws of
thermodynamics are relevant to environmental
systems
• 1.1.5: Explain the nature of equilibria
Syllabus Statements
• 1.1.6: Define and explain the principles of positive
and negative feedback
• 1.1.7: Describe transfer and transformation
processes
• 1.1.8: Distinguish between flows (inputs and
outputs), and storages (stock) in relation to systems.
• 1.1.9: construct and analyze quantitative models
involving flows and storages in a system
• Evaluate the Strengths and limitations of models
Vocab
•
•
•
•
•
Correlation
Entropy
Equilibrium
Feedback
Model
Systems
•
A system is a set of components that…
1. Function and interact in some regular,
predictable manner.
2. Can be isolated for the purposes of observation
and study.
Systems on Many Scales
•
•
•
•
Small scale local habitat – Scrub habitat
Ecosystem – The everglades in South FL
Biome – Tropical Rainforest
The entire planet – Gaia hypothesis
System Types
Exchanges
Examples
Open
Closed
Isolated
Exchanges
matter and
energy with
the
surroundings
Ecosystems
Exchanges
energy only
with the
surroundings
Exchanges
neither matter
nor energy
with its
surroundings
The entire
cosmos
Nutrient
cycles,
Biosphere 2
Components of systems
• Inputs = things entering the system  matter,
energy, information
• Flows / throughputs = passage of elements
within the system at certain rates (transfers
and transformations)
• Stores / storage areas = within a system,
where matter, energy, information can
accumulate for a length of time (stocks)
• Outputs = flowing out of the system into sinks
in the environment
Types of Flows: Transfer vs.
Transformation
• Transfers  flow through the system, involving a
change in location
• Transformation  lead to interactions in the
system, changes of state or forming new end
products
-Example: Water processes
Runoff = transfer, Evaporation = transformation
Detritus entering lake = transfer,
Decomposition
of detritus is transformation
Systems and Energy
• 1st Law: Energy can be transferred and transformed
but it can never be created nor destroyed
• So…
– All energy in living systems comes from the sun
– Into producers through photosynthesis, then consumers
up the food web
• 2nd Law: With every energy transfer or
transformation energy dissipates (heat) so the
energy available to do work decreases
• So…
– Always less energy at higher trophic levels
Positive feedback
•
•
•
A runaway cycle – often called vicious cycles
A change in a certain direction provides output that
further increases that change
Change leads to increasing change – it accelerates
deviation
Example: Global warming
1. Temperature increases  Ice caps melt
2. Less Ice cap surface area  Less sunlight is reflected away
from earth (albedo)
3. More light hits dark ocean and heat is trapped
4. Further temperature increase  Further melting of the ice
Negative feedback
• One change leads to a result that lessens the original
change
• Self regulating method of control leading to the
maintenance of a steady state equilibrium
• Predator Prey is a classic Example
–
–
–
–
–
Snowshoe hare population increases
More food for Lynx  Lynx population increases
Increased predation on hares  hare population declines
Less food for Lynx  Lynx population declines
Less predation  Increase in hare population
Which of the populations show positive feedback?
Which of the populations show negative feedback?
Positive or Negative?
• If a pond ecosystem became
polluted with nitrates,
washed off agricultural land
by surface runoff, algae
would rapidly grow in the
pond. The amount of
dissolved oxygen in the
water would decrease,
killing the fish. The
decomposers that would
increase due to the dead
fish would further decrease
the amount of dissolved
oxygen and so on...
• A good supply of grass for
rabbits to eat will attract
more rabbits to the area,
which puts pressure on the
grass, so it dies back, so the
decreased food supply leads
to a decrease in population
because of death or out
migration, which takes away
the pressure on the grass,
which leads to more growth
and a good supply of food
which leads to a more
rabbits attracted to the area
which puts pressure on the
grass and so on and on....
End result? Equilibrium…
• A sort of equalization or end point
• Steady state equilibrium  constant changes in all
directions maintain a constant state (no net change)
– common to most open systems in nature
• Static equilibrium  No change at all – condition to
which most natural systems can be compared but
this does not exist
• Long term changes in equilibrium point do occur
(evolution, succession)
• Equilibrium is stable (systems tend to return to the
original equilibrium after disturbances)
Equilibrium generally maintained by negative
feedback – inputs should equal outputs
Evaluate the Strengths &
Weaknesses of models
• Used when we can’t accurately measure the
real event
• Models are hard with
the environment
because there are so
many interacting
variables – but nothing
else could do better
• Allows us to predict
likelihood of events
• They are
approximations
• They may yield very
different results from
each other or actual
events
• There are always
unanticipated
possibilities…
• Discontinuities,
Synergistic interactions,
Chaotic events
Create a systems Diagram / or list inputs,
outputs, transfer/transfomations for
1.
2.
3.
4.
5.
6.
7.
Norwegian Salmon Farm
Rice Fish Agriculture
Sugar Cane Agriculture
Scrub Habitat
Sewage Treatment Plant
Amazon Rainforest
Slash & Burn Agriculture peasant farm in Costa Rica
Syllabus Statements
• 2.1.1: Distinguish between biotic and abiotic
(physical) components of an ecosystem
• 2.1.2: Define trophic level
• 2.1.3: Identify and explain trophic levels in food
chains and food webs selected from a local
environment
• 2.1.4: Explain the principles of pyramids of numbers,
pyramids of biomass and pyramids of productivity,
and construct pyramids from given data
• 2.1.5: Discuss how the pyramid structure effects the
functioning of an ecosystem
Syllabus Statements
• 2.1.6: Define the terms species, population,
community, niche and habitat with reference
to local examples
• 2.1.7: Describe and explain population
interactions using examples of named species
Ecosystem Components
2 parts
– Abiotic – nonliving components
(water, air, nutrients, soils solar
energy (insolation))
– Biotic – living components
(plants, animals, microorganisms)
Biota
Trophic Level
• The position that an organism occupies in a
food chain, or a group of organisms in a
community that occupy the same position in
food chains.
Identify and explain trophic level
Terminology and Roles of Biota
• Producers (Autotrophs) – Through
photosynthesis convert radiant to chemical
energy (energy transformation)
• Consumers (Heterotrophs) – Must consume
other organisms to meet their energy needs
– Herbivores, Carnivores, Omnivores, Scavengers,
Detritivores
• Decomposers – Break down organisms into
simple organic molecules (recycling materials)
Local examples
Trophic Level
Producer
Primary Consumer
Seconday Consumer
Tertiary Consumer
Quarternary Consumer
6th trophic level
Estuary system
Everglades habitat
Local examples
Trophic Level
Estuary system
Everglades habitat
Producer
Turtle grass
Phytoplankton
Primary Consumer
Grass shrimp
Zooplankton
Seconday Consumer
Pin fish
Blue gill
Tertiary Consumer
Spotted Sea trout
Bass
Quarternary Consumer
Osprey
Racoon
6th trophic level
Aligator
Figure 53.11 An antarctic marine food web: Identify the trophic levels
Pyramids
• Graphic models of quantitative differences
between trophic levels
• By second law of thermodynamics energy
decreases along food webs
• Pyramids are thus narrower as one ascends
– Pyramids of numbers may be different  large
individuals at low trophic levels – large forests
– Pyramids of biomass may skew if larger organisms are
at high trophic levels  biomass present at point in
time – open ocean
Losses in the pyramid
• Energy is lost between each trophic level, so
less remains for the next level
– Respiration, Homeostasis, Movement, Heat
• Mass is also lost at each level
– Waste, shedding, …
Pyramid types / characteristics
Biomass Pyramid
Numbers
pyramid
Energy pyramids
It shows
Storages
Storages
Flows
In
g / m2
individuals / m2
J / m2 yr or g / m2
yr
It’s always pyramid shaped
for a
Grassland
Grassland
There is never a
case where it isn’t
It is not pyramid
shaped for a(n)
Antarctic open
ocean habitat
Forest (especially
temperate
deciduous)
It is always
pyramid shaped
How does the first law of thermodynamics effect these?
How does the second law of thermodynamics effect these?
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
3. Biomagnification
1. Mostly Heavy metals & Pesticides
•
•
Insoluble in water, soluble in fats,
Resistant to biological and chemical degradation, not
biodegradable
2. Accumulate in fatty tissues of organisms
3. Amplify in food chains and webs
4. Sublethal effects in reproductive & immune
systems
5. Long term health effects in humans include
tumors, organ damage, …
Definitions
1.
2.
3.
4.
5.
Population  a group of individuals of a certain species in
a given area at a given time: blue crabs in the Halifax river
Community  interacting groups of populations in an area:
the scrub community on campus
Species  a group of individuals who can interbreed to
produce fertile, viable offspring: FL panthers
Niche  The role of an organism in its environment
(multidimensional): nocturnal predator of small mammals
in the forest
Habitat  Where an organism typically lives: mangrove
swamps
Intraspecific Competition
• Competition between members of the same
species for a common resource
• Resource: food, space, mates, etc.
• Territoriality
– Organisms patrol or mark an area
– Defend it against others
– Good territories have
• Abundant food, good nesting sites, low predator pop.
– Disadvantage = Energy, Reduce gene pool
Interspecific Competition
•
•
•
•
•
2 or more different species involved
Competing for food, space, sunlight, water, space,
nesting sites or other limited resource
If resources abundant, they can be shared but in
nature they are always limited
If fundamental niches overlap  competition
One of the species must…
1.
2.
3.
4.
Migrate if possible
Shift feeding habits or behavior = Evolve
Suffer a sharp population decline
Become extinct
Connell’s
Barnacles
Predation
• Members of one species feed
directly on all or part of a living
organism of a different species
• Individuals  predator
benefits, prey harmed
• Population  prey benefits:
take out the weak, greater
resource access, improved
gene pool
• Predator plays important
ecological role
Parasitism
•
•
•
One species feeds on part of another organism
(the host) without killing it
Specialized form of predation
Parasite Characteristics
1.
2.
3.
4.
•
Usually smaller than the host
Closely associated with host
Draws nourishment from & slowly weakens host
Rarely kills the host
Examples = Tapeworms, ticks, fleas, fungi
Malaria
According to the World Health
Organization there are 300 to 500
million clinical cases of malaria
each year resulting in 1.5 to 2.7
million deaths
The disease kills more than one
million children - 2,800 per day each year in Africa alone. In
regions of intense transmission,
40% of toddlers may die of acute
malaria.
In the early 1960s, only 10% the
world's population was at risk of
contracting malaria. This rose to
40% as mosquitoes developed
resistance to pesticides and
malaria parasites developed
resistance to treatment drugs.
Malaria is now spreading to areas
previously free of the disease.
Mutualism
• Symbiotic
relationship where
both species benefit
• Pollination,
Nutrition, Protection
are main benefits
• Not really
cooperation, both
benefit by exploiting
the other
Oxpeckers and black rhinoceros
Clown fish and sea anemone
Mutualism II
Examples
1. Lichens – fungi & algae living together 
food for one, structure for the other
2. Plants and Rhizobium bacteria  one gets
sugars the other gets nitrogen
3. Oxpeckers and Rhinos  food for one, less
parasites for the other
4. Protists and termites  break down wood
for one, nutrients for the other
•
One species benefits
the other is neither
harmed nor helped
– Examples
1. Herbs growing in the
shade of trees
2. Birds building nests in
trees
3. Epiphytes = “Air plants” which attach themselves
to the trunk or branches
of trees
-they have a solid base to grow
on and better access to
sunlight & rain
Commensalism
Syllabus Statements
• 2.2.1: List the significant abiotic (physical) factors
of an ecosystem
• 2.2.2: Describe and evaluate methods for
measuring at least three abiotic factors in an
ecosystem
Aquatic Life Zones
Terrestrial Ecosystems
• Light penetration
• Sunlight
• Water currents
• Temperature
• Dissolved nutrient concentrations (especially N
and P)
• Precipitation
• Wind
• Latitude (distance from equator)
• Altitude (distance above sea level)
• Suspended solids
• Salinity
• Fire frequency
• Soil
Significant abiotic factors
Techniques to measure abiotic factors
• Terrestrial
– Light intensity or insolation ( lux) –
light meter; consider effect of
vegetation, time of day…
– Temperature ( C) – themometer;
take at different heights, points,
times of day, seasons…
– Soil moisture (centibars) –
tensiometer of wet mass dry mass
of soil; consider depth of soil
sample, surrounding vegetation,
slope…
• Aquatic (specify marine or
fresh)
– Salinity (ppt) – hydrometer;
consider role of evaporation
– Dissolved Oxygen (mg/L) – DO
meter, Winkler titration; consider
living organisms, water
circulation,
– pH – pH probe or litmus paper;
consider rainfall input, soil and
water buffering capacity
– Turbidity (FTU) – Secchi disk or
turbidity meter; consider water
movement,
Measuring biotic components
Syllabus Statements
• 2.3.1: Construct simple keys and use
published keys for the identification of
organisms
• 2.3.2: Describe and evaluate methods for
estimating abundance of organisms
• 2.3.3: Describe and evaluate methods for
estimating the biomass of trophic levels in an
ecosystem
• 2.3.4: Define the term diversity
• 2.3.5: Apply Simpson’s diversity index and outline its significance
Vocab
•
•
•
•
•
System
Open System
Closed system
Isolated System
Stable Equilibrium
Step 1: Identify the organism
• Use dichotomous keys, field guides, observe a
museum collection, or consult an expert
• http://www.earthlife.net/insects/orderskey.html#key
• Sample key for insect ID
• http://people.virginia.edu/~sos-iwla/StreamStudy/Key/Key1.HTML
• Macroinvertebrate key
Construct you Own Dichotomous Key
Flounder
Cardinal Fish
Moray Eel
Goat fish
Hatchet fish
Southern Puffer
Eagle Ray
Coney
Trumpet Fish
Mark & Recapture Method
• Used for fish & wildlife populations
• Traps placed within boundaries of study area
• Captured animals are marked with tags, collars, bands or spots of
dye & then immediately released
• After a few days or weeks, enough time for the marked animals to
mix randomly with the others in the population, traps are set
again
• The proportion of marked (recaptured) animals in the second
trapping is assumed equal to the proportion of marked animals in
the whole population
• Repeat the recapture as many times as possible to ensure
accuracy of results
• Marking method should not affect the survival or fitness of the
organism
N = (# marked in first catch) (Total # in second catch)
# of Recaptures in second catch
Quadrat Method
•
1.
2.
3.
4.
5.
6.
7.
Used for plants or sessile organisms
Mark out a gridline along two edges of an area
Use a calculator or tables to generate two random numbers to
use as coordinates and place a quadrat on the ground with its
corner at these coordinates
Count how many individuals of your study population are inside
the quadrat
Repeat steps 2 & 3 as many times as possible
Measure the total size of the area occupied by the population
in square meters
Calculate the mean number of plants per quadrat. Then
calculate the population size with the following equation
N = (Mean # per quadrat) (total area)
Area of each quadrat
In addition to population size we can measure…
• Density = # of individuals per unit area
– Good measure of overall numbers
• Frequency = the proportion of quadrats sampled that contain
your species
– Assessment of patchiness of distribution
• % Cover = space within the quadrat occupied by each species
– Distinguishes the larger and smaller species
Evaluation of Sampling Techniques
CMR
What’s good
What’s bad
You don’t have to count every single organism in
the habitat
Best in closed
environments
Moving Organisms only
Quadrat Method
You don’t have to count every single organism in
the habitat
Quadrats that are
randomly placed may
never or rarely sample your
target species
Sessile Organisms only
Size must match the size of
organisms sampled
How do we get the biomass of a trophic level to
make these pyramids?
•
•
•
•
•
Why can’t we measure the biomass of an entire trophic level?
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
• sample biomass / sample area = total biomass / total area
• 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
– But it prevents you from killing the whole trophic level to get your
measurement
Diversity is?
Often considered as a function of two
components: the number of different species
& the relative number of individuals of each
species
Quantifiying this Diversity – Simpson’s Index
D = N (N – 1)
∑ n (n – 1)
• Where D = diversity index
N = total # of organisms of all species
n = # of individuals of particular species
Which sample is more diverse?
Flower Species Sample 1
Sample 2
Daisy
300
20
Dandelion
335
49
Buttercup
365
931
Total
1000
1000
Which has a higher richness? Evenness?
• Sample 1 = 2.99
• Sample 2 = 1.15
• High values of “D” suggests a stable and ancient site
• A low value of “D” could suggest pollution, recent colonization, or agricultural
management
• Index normally used in studies of vegetation
but can be applied to comparisons of diversity
of any species
Syllabus Statements
• 2.4.1: Define the term Biome
• 2.4.2: Explain the distribution, structure and
relative productivity of tropical rainforests, deserts,
tundra and any other biome
What is a biome?
• World climate is variable
– Differences in temperature and precipitation
– Different climates  Different communities
• Biomes = Regions of the earth characterized by
specific climates and community types
• Remember they cross national boundaries
• Real biomes do not have sharply defined
boundaries. Ecotones = Transitional zones
• Biomes not uniform, instead a mosiac of patches
– Vary in microclimate, soil types, disturbances
Tropic of
Cancer
Equator
Tropic of
Capricorn
Arctic tundra (polar grasslands)
Desert
Boreal forest (taiga), evergreen coniferous
forest (e.g., montane coniferous forest)
Tropical rain forest,
tropical evergreen forest
Semidesert,
arid grassland
Mountains
(complex zonation)
Temperate deciduous forest
Tropical deciduous forest
Ice
Temperate grassland
Tropical scrub forest
Dry woodlands and
shrublands (chaparral)
Tropical savanna,
thorn forest
Main Biome Effects
Altitude
Mountain
Ice and snow
Tundra (herbs,
lichens,
mosses)
Coniferous
Forest
Latitude
Deciduous
Forest
Tropical
Forest
Tropical
Forest
Deciduous
Forest
Coniferous
Forest
Tundra (herbs,
lichens, mosses)
Climate and vegetation vary in a predictable
fashion with changes in Altitude and Latitude
Polar ice
and snow
100
30
20
50
10
ft
m
Tropical
rain forest
Coniferous
forest
Deciduous
forest
Thorn
forest
Thorn
scrub
Tall-grass
prairie
Short-grass
prairie
Comparison of types, sizes and stratification of species
in different terrestrial biomes (structure)
Desert
scrub
Tundra
1. Climate
•
•
•
Precipitation < 15 cm / yr – mostly snow & summer rain Arid
Bitter cold  -57 – 50 C - permafrost
low insolation gives short growing season
2. Distribution
•
•
60 – 75 N latitude – northern North America, Asia,
Greenland
About 20% of the earth’s surface
3. Structure
•
•
Simple – low spongy mat of vegetation, lichens, mosses
Even trees are less than knee high
4. Relative Productivity
•
Low – limited by temperature and insolation
Temperate Grasslands
1.
Climate
•
•
•
•
2.
Precipitation 25-45 cm / yr – enough to grow grass, erratic Semiarid
fire, drought, animals prevent tree growth
May be Tropical, Temperate
Moderate insolation
Distribution
•
•
3.
9% of earth surface  Temperate Latitudes – Major onesNA tall grass prairie,
steppes, pampas, veldt
Grasslands overall up to 40% of earth’s surface
Structure
•
4.
Simple – grasses and herbaceous plants
Relative Productivity
•
Medium to high – high turnover of grasses, rich soils
Deserts
1. Climate
•
•
•
Precipitation < 25 cm / yr – scattered unevenly through year
Arid
May be Tropical, Temperate and Cold types – always extremes
High to moderate insolation
2. Distribution
•
30% of earth surface  between 30 degrees north and south of
the equator – Major ones Saraha (Africa), Gobi (Asia), Mojave
(N. america)
3. Structure
•
•
Simple – very little vegetation
Most complex is temperate desert which has largest cacti
4. Relative Productivity
•
Low – limited by water availability
Tropical Rainforest
1.
Climate
•
•
•
2.
Precipitation over 150 cm / yr – Wet – still rainy and dry seasons
Warm humid year round climate  80 F
high insolation gives long growing season
Distribution
•
•
•
3.
23.5 N to 23.5 S latitude – Tropic of Capricorn to Cancer
About 2% of the earth’s surface
Three chunks – S. & C. America, C. Africa, SE Asia
Structure
•
•
4.
Complex – stratified layers
High diversity - 50-80% of terrestrial species
Relative Productivity
•
Highest in terrestrial system – unlimited by temperature and insolation
Syllabus Statements
• 2.5.1: Explain the role of producers consumers and
decomposers in an ecosystem
• 2.5.2: Describe photosynthesis and respiration in
terms of inputs, outputs and energy transformations.
• 2.5.3: Describe and explain the transfer and
transformation of energy as it flows through an
ecosystem
• 2.5.4: Describe and explain the transfer and
transformation of materials as they cycle within an
ecosystem
Syllabus Statements
• 2.5.5: Define the terms gross productivity, net productivity,
primary productivity, and secondary productivity
• 2.5.6: Define the terms and calculate the values of gross
primary productivity (GPP) and net primary productivity
(NPP) from given data.
• 2.5.7: Define the terms and calculate the values of gross
secondary productivity (GSP) and net secondary
productivity (NSP) from given data.
Vocab
•
•
•
•
•
Steady State Equilibrium
Negative Feedback
Positive Feedback
Abiotic Factor
Biotic Factor
Terminology and Roles of Biota
• Producers (Autotrophs) – Through
photosynthesis convert radiant to chemical
energy (energy transformation)
• Consumers (Heterotrophs) – Must consume
other organisms to meet their energy needs
– Herbivores, Carnivores, Omnivores, Scavengers,
Detritivores
• Decomposers – Break down organisms into
simple organic molecules (recycling materials)
Explain Photosynthesis and
Respiration in Systems Terms
Inputs
Outputs
Photosynthesis
sunlight, carbon
dioxide, water
sugars, oxygen
Matter
Transformations
inorganic carbon
(CO2) into organic
carbon (C6H12O6)
Energy
Transformations
radiant energy into
chemical energy
Respiration
sugars, oxygen
ATP, carbon dioxide,
water
organic carbon
compounds into
inorganic carbon
compounds
chemical energy in
carbon compounds
into chemical
energy as ATP
Energy to Earth
• 30% solar energy reflected back into space by
atmosphere, clouds, ice
• 20% absorbed by clouds & atmosphere
• 50% remaining
– Warms troposphere and land
– Evaporates and cycles water
– Generates wind
• < 0.1% captured by producers for photosynthesis
• Energy eventually transformed to heat and trapped by
atmosphere “Natural Greenhouse Effect”
• Eventually reradiated into space
Construct and analyze
energy flow diagrams for
energy movement
through ecosystems
• Trophic level boxes are
storages – biomass per
area (g m-2)
• Energy Flow in arrows –
rate of energy transfer
(g m-2 day-1)
Transfers
Transformations
Organic Storages
Inorganic Storages
Water cycle Precipitation,
Runoff,
Infiltration,
Percolation
Evaporation,
Condensation,
Melting
Plants, Animals
Ocean,
Atmosphere,
Aquifer
Nitrogen
Cycle
Consumption,
absorption
Nitrogen Fixation,
Ammonification,
Denitrification,
Nitrification,
Assimilation
Organisms,
Bacteria
Soil, Atmosphere,
Water, Rocks
Carbon
cycle
Consumption,
Assimilation,
Photosynthesis,
Respiration,
Combustion,
Decomposition,
Incomplete
Fossilization
PLANTS,
Organisms
Fossil Fuels,
Atmosphere, Rocks
(limestone), Water
as carbonic acid
Make sure you can define all of those
transfers and transformations
Definitions
1. gross productivity – total biomass produced
2. net productivity – total biomass produced minus
amount used by organism
3. primary productivity – productivity at 1st trophic
level
4. secondary productivity – productivity at higher
trophic level
5. gross primary productivity – rate at which
producers use photosynthesis to make more
biomass
6. net primary productivity – rate at which energy for
use by consumers is stored in new biomass
Productivity Calculations
• Gross Primary Production (GPP)  Amount of light
energy converted into chemical energy by
photosynthesis per unit time
– Joules / Meter2 / year
• Net Primary Production (NPP) 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
Secondary Productivity
• Gross Secondary Productivity (GSP)  Total
gain by consumers in energy or biomass per
unit area per unit time through absorption
(What they eat, digest and absorb)
• Net Secondary Productivity (NSP)  The gain
by consumers in energy or biomass per unit
time remaining after allowing for respiratory
losses (R)
Equations
Producers
• NPP = GPP – R
Consumers
• GSP = Food eaten – fecal losses
• NSP = change in mass over time
• NSP = GSP – R
Measuring productivity will work for an
experimental design on biotic components if
they ask you
•
•
•
•
•
BOD Bottles
Technique
– Measure changes in DO over a ½ to 24
hour period
– Use light and dark BOD 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=I-D
•
Evaluation
•
•
–
Tough in unproductive waters or for short
incubation times
GSP Techniques
•
Technique
•
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
•
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
Syllabus Statements
• 2.6.1: Explain the concepts of limiting factors and carrying capacity
in the context of population growth
• 2.6.2: Describe and explain s and J population curves
• 2.6.3: Describe the role of density-dependent and densityindependent factors and internal and external factors, in the
regulation of population
• 2.6.4: Describe the principles associated with survivorship curves
including K and r-strategists
• 2.6.5 – Describe the concept and process of succession in a named
habitat
• 2.6.6 – Explain the changes in energy flow, gross and net
productivity, diversity and mineral cycling in different stages of
succession
• 2.6.7 – Describe the factors affecting the nature of climax
communities
Vocab
•
•
•
•
•
•
•
Gross Productivity
Gross primary productivity
Gross secondary productivity
Net productivity
Net primary productivity
Primary productivity
Secondary productivity
Forms of Growth
• Exponential growth  starts slow and proceeds
with increasing speed
– J curve results
– Occurs with few or no resource limitations
• Logistic growth  (1) exponential growth, (2)
slower growth (3) then plateau at carrying
capacity
– S curve results
– Population will fluctuate around carrying capacity
Population Growth Curves Ideal
© 2004 Brooks/Cole – Thomson Learning
Population size (N)
Population size (N)
K
Time (t)
Exponential Growth
Time (t)
Logistic Growth
Capacity for Growth
• Capacity for growth = Biotic potential
• Rate at which a population grows with unlimited
resources is intrinsic rate of increase (r)
• High (r)  (1)reproduce early in life, (2)short generation
time, (3)multiple reproductive events, (4)many offspring
each time
• BUT – no population can grow indefinitely
• Always limits on population growth in nature
Carrying Capacity
• Environmental resistance = all factors which
limit the growth of populations
• Population size depends on interaction
between biotic potential and environmental
resistance
• Carrying capacity (K) = # of individuals of a
given population which can be sustained
infinitely in a given area
Limiting Factors
• Carrying capacity established by limited resources in
the environment
• Only one resource needs to be limiting even if there
is an over abundance of everything else
• Ex. Space, food, water, soil nutrients, sunlight,
predators, competition, disease
• A desert plant is limited by…
• Birds nesting on an island are limited by…
Density Effects
• Density Independent Factors: effects regardless
of population density
• Mostly regulates r-strategists
– Floods, fires, weather, habitat destruction, pollution
– Weather is most important factor
Density Effects
• Density dependent Factors: effects based on amount of
individuals in an area
• Operate as negative feedback mechanisms leading to
stability or regulation of population
External Factors
– Competition, predation, parasitism
– Disease – most epidemics spread in cramped conditions
Internal Factors
– Reproductive effects  Density dependent fertility, Breeding
territory size
R vs K strategists and survivorship
• Two idealized categories for reproductive patterns but really it’s a continuum
• r-selected & K-selected species depending on position on sigmoid
population curve
• r-selected species: (opportunists) reproduce early, many young
few survive
– Common after disturbance, but poor competitors
• K-selected species: (competitors) reproduce late, few young most
survive
– Common in stable areas, strong competitors
Survivorship curves
•
•
Different life expectancies for different species
Survivorship curve: shows age structure of
population
1. Late loss curve: K-selected species with few young
cared for until reproductive age
2. Early loss curve: r-selected species many die early
but high survivorship after certain age
3. Constant loss curve: intermediate steady mortality
Percentage surviving (log scale)
100
10
1
0
Age
Communities Change
• Ecological Succession: the gradual change in
species composition of a given area over time
• Species do change spatially within an area at a
certain point in time, this is zonation not
succession
• 2 Types depending on start point
– Primary succession: gradual establishment of
biological communities on lifeless ground
– Secondary succession: reestablishment of biotic
communities in an area where they already existed
What changes occur through
Succession?
1. Diversity
• Starts very low in harsh conditions few species
tolerate – r selected species types
• Middle succession mix of various species types –
most diverse (role of disturbance)
• Climax – k selected species strong competitors
dominate
2. Mineral Cycling
• Pioneer, physical breakdown & make organic,
Later processing increase – cycles expand
3. Gross productivity changes (total photosynthesis)
• Pioneer = Low density of producers at first
• Middle & climax = high  lots of producers and
consumers
4. Net Productivity (G – R = N)
• Pioneer = little respiration so Net is large  system is
growing, biomass accumulating
• Middle & climax = respiration increases dramatically 
N approaches zero (P:R = 1)
5. Energy flow
• # of trophic levels increases over time
• Energy lost as heat increases with more transfers
Climax community
• Characterized by K-selected species
• Determined by
– climate in the area – temperature, weather patterns
– Edaphic factors – saturated wet, mesic, arid
• Climax community structure is in stable equilibrium
for each area
• Humans & other factors may maintain an
equilibrium below climax
– E.g. current warming trends make climax rainforest
communities w/ softer wood, faster growing species
Syllabus Statements
• 2.7.1 – Describe and evaluate methods of measuring
change in abiotic and biotic components of an
ecosystem along an environmental gradient
• 2.7.2: Describe and evaluate methods for measuring
change in abiotic and biotic components of an
ecosystem due to a specific human activity
• 2.7.3: Describe and evaluate the use of
environmental impact assessment (EIAs)
So how could you measure changes in biotic and
abiotic factors along an environmental gradient?
• Biota = living organisms
• Change in benthic (bottom) community of
rocky intertidal with increased depth
• Gradient in moisture or drying
• Use modified quadrat method
– run transect into deeper water
– At set depths place quadrat and sample organisms
– Do repeated transects along your sample area
– Calculate differences in communities with depth
Abiotic – pick the variable and test samples at
How can we measure change in biotic and
abiotic components due to a specific human
activity
•
1.
2.
3.
4.
Measure a comparable area at
the same time
Pick an area with similar habitat
characteristics as your impacted
area
Pick an index to use
-Biotic: population numbers,
biodiversity, etc
-Abiotic: chemical test, DO,
specific pollutant
Choose an appropriate sampling
method (CMR, quadrat)
Monitor over time and compare
changes
• Pre and Post impact
assessment
1. In the area where the
impact will take place
2. Do steps 2-4 from 
3. Start a reasonable
amount of time before
the impact and
continue afterwards
Measuring the effects of Eutrophication
•
•
•
•
•
•
•
•
•
•
•
•
A Method
Compare two ponds of comparable size, habitat etc that differ in proximity to a
cattle feed lot
Variables to study = DO, algal density
Take satellite images before and after if possible but specifically over time and see
changes in turbidity in both ponds
Sample fixed volume of water and filter out algae – calculate density changes over
time
Sample remaining water for DO use as a means of doing BOD experiment
In each case T-tests will show you if the ponds are different
Evaluate
Other factors like temp can effect DO
Satellite images can be inaccurate
Eutrophication is part of natural aquatic succession
GOOD  These variables are good indicators of the amount of eutrophication that
is happening
Environmental Impact Statements
•
•
•
•
•
•
•
•
•
An EIS typically has four sections:
An Introduction including a statement of the Purpose and Need of the Proposed Action.
A description of the Affected Environment.
A Range of Alternatives to the proposed action. Alternatives are considered the "heart" of
the EIS.
An analysis of the environmental impacts of each of the possible alternatives.
While not required in the EIS, the following subjects may be included as part of the EIS or
as separate documents based on agency policy.
Financial Plan for the proposed action identifying the sources of secured funding for the
action. For example, the Federal Highway Administration has started requiring states to
include a financial plan showing that funding has been secured for major highway projects
before it will approve an EIS and issue a Record of Decision.
An Environmental Mitigation Plan is often requested by the Environmental Protection
Agency (EPA) if substantial environmental impacts are expected from the preferred
alternative.
Additional documentation to comply with state and local environmental policy laws and
secure required federal, state, and local permits before the action can proceed
Steps will include pre, during and
post impact assessments
1. Produce a baseline study to see how the
environment is in a natural state (done
before any environmental development)
2. Assessment of possible impacts
3. Monitor change during the development
4. Monitor change after the development
http://www.eqb.state.mn.us/resource.html?Id=
17304