Download Chapter 3 Ecosystem Ecology

• In 1923 over 60% of country covered in forests.
• By 2006 with more than 9000 people, less than 2%
remains forested.
Causes behind the Deforestation of Haiti
• Poverty forcing people to use charcoal
for fuel
Reasons why Haiti is fighting to reverse
Deforestation
• Massive mudslides due to soil erosion
• Mango trees can be a source of income
Extra notes:
• Alternative fuels are being researched to help give people a cheap fuel they can use other then charcoal.
ecosystem is a particular location on Earth with interacting biotic and
abiotic components.
 An
 Ecosystems are dependent on climate (temperature and rainfall)…determine plant growth
which provides food for other trophic levels.
 Ecosystem boundaries are not well defined
 Sometimes it is easy to determine boundaries (cave, lake, stream)
 For most ecosystems, it is subjective as to where one ecosystem ends and another
begins….
 Can be defined by a species range or topographic features
 Transition zones: overlap of biotic and abiotic components from both ecosystems
 Vegetation, soil type, topography
Human-created Boundaries
• Set according to administration
rather then scientific
created….National park
Natural Boundaries
• Set by abiotic and biotic
components
Ecosystem Processes
Even though it is helpful to distinguish between two
different ecosystems, ecosystems interact with other
ecosystems through the exchange of matter and energy.
Biosphere: combination of all ecosystems on Earth
Photosynthesis and Respiration
Producers
(autotrophs) are
able to use the
suns energy to
produce usable
energy through
the process
called
photosynthesis
Cellular
respiration is
the process by
which other
organisms
gain energy
from eating
the tissues of
producers.
• Photosynthesis converts energy from the Sun
to chemical energy for organisms to
consume.
• Without photosynthesis, there would be no
usable energy for heterotrophs and food
webs would not exist.
• Photosynthesis also produces the oxygen
that organisms need to perform cellular
respiration.
• Organisms need cellular respiration to
convert the chemical energy found in
food to ATP, a form of energy that fuels
their metabolism and growth.
• Without cellular respiration, organisms
would not be able to convert chemical
energy into a usable form.
 Consumers (heterotrophs)-
obtain energy by consuming other
organisms.
 Primary Consumers (herbivores)consume producers.
 Secondary Consumers
(carnivores)- obtain their energy
by eating primary consumers.
 Tertiary Consumers (carnivores)eat secondary consumers.
 Quaternary Consumers
(carnivores)- eat tertiary
consumers.
 Terrestrial (land): Maximum is generally 4 to 5 levels starting with
producer and running through quaternary consumer.
 Aquatic ecosystems can generally go 5 to 6 trophic levels.
Why? Let’s explain using popcorn…..
 Food Chain- The sequence of consumption from
producers through tertiary consumers.
 Food Web- A more realistic type of food chain
that takes into account the complexity of nature.
Food web: more
realistic type of model
depicting the
connectedness of
ecosystems
 Gross primary
productivity (GPP)- The
total amount of solar
energy that the producers
in an ecosystem capture via
photosynthesis over a given
amount of time.
 Net primary productivity
(NPP)- The energy
captured (GPP) minus the
energy respired by
producers.
NPP=GPP-respiration by producers.
We will do an
activity to
reinforce these
terms!!
 Biomass- The energy in an ecosystem is measured in
terms of biomass.
 Standing crop- The amount of biomass present in an
ecosystem at a particular time.
 Ecological efficiency- The proportion of consumed
energy that can be passed from one trophic level to
another.
 Trophic pyramid- The representation of the
distribution of biomass among trophic levels.
 What determines the productivity of an ecosystem?
 Amount of sunlight and water
 Nutrients, natural disasters
 GPP vs. NPP: An analogy
 GPP = equate to the total amount of calories we take in from food
 We burn many of these calories during cellular respiration (moving, digesting, etc.)
 Plants take in solar energy (the amount they take in = GPP)
 NPP = the calories we don’t use…it is the calories we store in our tissues as fat
 Like the calories stored in plant tissue
 Look at page 76….
 What accounts for the large difference in NPP among different ecosystems?
 Climate and amount of biomass
 Which ecosystem would vary the most over the course of the year? Why?
 Temperate regions…seasons!!!
 Are the rates of cellular respiration the same in each ecosystem? Why or why not?
 No!! Temperature! Biomass!!
Check out this video for a great overview of matter cycles: https://www.youtube.com/watch?v=09_sWPxQymA
 Biosphere- The combination of all ecosystems on Earth.
Region of the planet where life exists.
 Matter cycles within the biosphere.
 Biogeochemical cycles- The movement of matter within
and between ecosystems involving biological, geologic and
chemical processes.
 All of Earth’s living organisms are composed of chemical
elements-mostly N-CHOPS.
 The movement of water through the
biosphere.
 Water allows essential molecules to move within and
between cells, draws nutrients into the leaves of trees,
dissolves and removes toxic materials, and performs many
other critical biological functions.
 Water is the primary agent responsible for dissolving and
transporting the chemical elements necessary for living
organisms.
 Transpiration- The process where plants release
water from their leaves into the atmosphere.
 Evapotranspiration- The combined amount of
evaporation and transpiration.
 Runoff- When water moves across the land
surface into streams and rivers, eventually
reaching the ocean.
 Know also: evaporation, condensation,
precipitation, infiltration, percolation, leaching.
Six processes that drive the
carbon cycle:
•
•
•
•
•
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Photosynthesis
Respiration
Exchange
Sedimentation and burial
Extraction
Combustion
Carbon Cycle Animation
Carbon Processes
 The
fast processes: associated with living organisms (food
chain/web, photosynthesis, respiration, decomposition)
 The
slow processes: Those held in rock, soil, or petroleum.
 Slow part is in steady state.
 Oil formation
 http://sciencelearn.org.nz/Contexts/Future-Fuels/Sci-Media/Animations-and-Interactives/Oil-
formation
 A lot of carbon is exchanged between the atmosphere and the ocean.
Deforestation
 https://www.youtube.com/watch?v=5xQnFhIRR88
 After watching (3 minutes)….List important carbon
storage data from the Forest 101 video. Which data
helps you to understand the importance of trees and
forests in storing carbon? Why?
 CNN Explains
 Combustion of Fossil Fuels
Watch this 3 minute video:
http://www.npr.org/news/specials/climate/video/k
rulwich.html
•
•
•
•
•
Nitrogen: the most abundant
element in the atmosphere.
Often a limiting nutrient for
producers…Used in fertilizer
for this reason
Used to form amino
acids/proteins and nucleic
acids such as DNA and RNA.
3% total body weight comes
from nitrogen
Atmospheric nitrogen is
unusable…it must be fixed!!!
https://www.youtube.com/watch?v=leHy-Y_8nRs
 Nitrogen fixation: Conversion of nitrogen gas
(N2) to ammonia (usable by plants)
 Lightning
 Nitrogen-fixing bacteria (found naturally such as
cyanobacteria (blue green algae) or in root nodules
of legumes)
 Nitrification: bacteria convert ammonia (NH3)
into nitrites (NO2) then into nitrates (NO3)
 Denitrification: denitrifying bacteria convert
nitrates back into nitrogen gas (N2)
Product
Process
FIX-Nitrogen fixation
Ammonia
Nitrification
Nitrates
Assimilation
Proteins
Ammonification
Ammonia
Denitrification
Nitrogen
Fix NAAD ANPAN
 Draw a diagram of the nitrogen cycle.
 Box the main nitrogen reservoirs: atmosphere, plants,
animals
 Circle the main forms of nitrogen: N2, ammonium, nitrate
 Title the arrows with the main processes: ammonification
(mineralization), assimilation, denitrification,
nitrification, and nitrogen fixation
 Application of fertilizers
 Leaching: water infiltrates into the ground carrying
nitrates into groundwater
 Increase in atmospheric nitrogen
 Lowers biodiversity
 Eutrophication (hypoxia brought on by an abundance of
producers)
 Phosphorus is a major
component of DNA, RNA
and ATP (molecule used
by cells to transfer
energy).
 Limiting factor for
terrestrial plants (second
only to Nitrogen)
 No gaseous component
 Primary limiting nutrient
in fresh water and
marine ecosystems.
 P inputs into P-limited
aquatic ecosystems can
cause rapid growth of algae
(algal bloom). Algal blooms
quickly increase the amount
of biomass. Algae
eventually die, initiating
decomposition which uses
up Oxygen.
Causes Hypoxia (dead zone)
Major sources of P: Laundry detergents (1940’s-1990) and fertilizers for agriculture.
No more phosphates in laundry detergents (1994) and dish detergents (2010)
Nutrients
 Matter that organisms require for their life
processes.
 Macronutrients vs. Micronutrients
Nutrients required in
Large amounts like
Carbon, Oxygen,
Nitrogen and Phosphorus
Nutrients required in
Small amounts like
Potassium, Calcium,
Iron, etc.
Sulfur Cycle
 Slow cycling and scarcely available
 Sulfur is important for the functioning of proteins and
enzymes in plants, and in animals that depend upon plants
for sulfur.
 Most of the earth's sulfur is tied up in rocks and salts or
buried deep in the ocean in oceanic sediments
 Causes acid precipitation by combustion of fossil fuels
which will release SO2 into the atmosphere to act as a
pollutant.
 Disturbance- An event caused by physical,
chemical or biological agents that results in
changes in population size or community
composition.
 Watershed- All of the
land in a given
landscape that drains
into a particular stream,
river, lake or wetland.
 New Hampshire
 Studied since 1962.
 Several watersheds all draining to
the same main stream.
 Scientists measured the effects of
clear cutting on one of the
watersheds and compared it to
another that was not clear cut.
 Found that the clear cut watershed
caused leaching of nutrients (nitrogen)
from the soil.
 Resistance- A measure of how much a disturbance
can affect its flows of energy and matter.
 High resistance means disturbance has little to no
effect.
 Resilience- The rate at which an ecosystem returns
to its original state after a disturbance.
 High resilience means the ecosystem recovers
quickly…..succession can ensue quickly
 Restoration ecology- A new scientific discipline
that is interested in restoring damaged ecosystems.
 The intermediate
disturbance
hypothesis- states
that ecosystems
experiencing
intermediate
levels of
disturbance are
more diverse than
those with high or
low disturbance
levels.