Read:
Ecosystem Services
Ecosystems
 Ecosystem: all living things in a particular place and the nonliving
(abiotic) environment in which they live
o All components of an ecosystem interact with one another
o Components of an ecosystem are highly interconnected
o Different ecosystems are connected
 Ecosystems defined at different levels
 Salt marsh (where ocean meets lakes/rivers) [Mississippi River, Gulf of
Mexico, land… lots of interactions]
Energy and matter in ecosystems
 Ecosystems provide services that are essential to support all life on
earth
o Capture and transfer of energy
 Energy flows through ecosystem
 Earth is an open energy system
o Storage and transfer of matter
 Matter and elements cycle through ecosystems
 The right amount of matter at the right time to support
 Earth is a closed system with respect to matter (no
matter is ever created or destroyed, only recycled
through the system)
Ecosystems energy
 The earth is an open system with regard to energy
o Constant energy from the sun
o Very little energy from the sun is captured for use
o Emits thermal energy into space
 Figure 57.10
Capture of matter and energy
 Autotrophs: synthesize organic compounds from inorganic
molecules
o Auto = self; troph = feeding
o Photosynthetic: energy from sunlight to make organic
compounds (sugars)
o Autolithortrophs: oxidize inorganic compounds (H2S, S, Fe, H2)
to obtain energy to make organic compounds
Transfer of matter and energy
 Heterotrophs: cannot synthesize organic compounds
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Live by taking organic compounds and energy from other
organisms
o Primary consumers: eat producers
o Secondary consumers: eat primary consumers
Trophic level: an energy/matter transfer level in a food chain
Trophic level energy transfer
 Figure 57.8
 How much energy is available to producers? Consumers? 2nd
Consumers?
 Remember the 2nd law! Nature is always increasing entropy, always
losing some energy.
 About 10% available as we move up trophic levels
Energy loss in organisms
 Figure 57.9
 Most acquired energy is lost as heat
 Living organisms can not transfer heat energy
 Only energy stored in chemical bonds (biomass) can move up to
the next trophic levels
Ecological Pyramids
 Figure 57.12, Figure 57.13
Matter in an ecosystem
 All organisms are made of 6 primary atoms: C H O N P S
o Plus: Na Cl K Ca Mg Fe (smaller amounts)
 Limited amount of C H O N P S
 Matter cycles through biotic and abiotic parts of an ecosystem
o Proper cycling required for life
o Disruption of cycling decreases capacity of the earth to
support life
Cycling of CHONPS
 We’ll ignore small and trace elements
 Concentrate on C H O N P S plus H2O
o Each has reservoir
o At any time most of an element is in its reservoir
Reservoir of element
Return
Incorporation
Organisms
Reservoirs
 Can be:
o Air: atmosphere
o Water: ocean, lakes, streams
o Sediment: soil, rocks, seabed
 Differ vastly in how accessible they are
 Role of decomposers important:
o Make C H O N P S available from dead organisms, leaf litter
and other waste etc.
o Recycling
Two major types of reservoir
 Reservoir is water or atmosphere
o Carbon: CO2 of atmosphere (primary)
o Nitrogen: N2 of atmosphere (80%)
o Hydrogen: H2O (primary)
o Oxygen: H2O (primary), CO2
 Reservoir is sediment
o Phosphorous: PO43- seabed, soil, rocks
o Sulfur: sediment (primary), air
The water cycle
 Water circulates from earth’s surface to the atmosphere
 Relies on evaporation & precipitation
 Evaporation
o Occurs directly from bodies of water. (heat must be present)
o Terrestrial ecosystems rely on plants for evaporation
(transpiration – stomata on leaves to get CO2)
o Purifies the water
 Move H2O from soil to atmosphere
 Brings about precipitation
 Figure 57.2
Disruption of the water cycle
 Deforestation (large scale clear cutting)
o Permanently change rainfall patterns
 Development – malls, schools, parking lots, factories, etc.
o Increase water runoff and fresh water loss
o Pollution (ex: New York City)
o Prevents evaporation cooling: urban heat island
 Affects other cycle:
o Loss of organic nutrients
o Alters retention of bio-available forms
Read:
Carbon cycle
 Carbon is cycled through the biosphere through photosynthesis and
respiration
o Photosynthesis: CO2 + H2O -> organic sugars (synthesis)
o Respiration: Organic sugars -> CO2 + H2O (degredation)
 Carbon cycling inputs and outputs can be and are unbalanced
 Figure 57.1
Carbon, Hydrogen, & oxygen: all interrelated
 Connects plants to everything else
 Connects photosynthesis & respiration
The nitrogen cycle
 No shortage of N
o 80% of air is N2 but N2 is very unreactive
o not usable by most organisms
o scarcity of useable nitrogen
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o Must convert to usable form
Two sources of useable nitrogen:
o Recycling
o Fixation
Recycling of organic nitrogen
 Occurs through microorganisms
 Are major source of useable nitrogen
o Decomposers reclaim usable N from dead organisms and
waste products
o Waste products (ammonium (NH4+) and urea are converted
to ammonia (NH3)
o Plants absorb NH3 – convert to nitrate (NO3-)
o Animals get bio available N (NH3 and NO3-) from plants
Nitrogen fixation: in nature
 Bacteria/plants
 Humans (industrial process) (not in your body)
 Bacterial Fixation:
o Symbiotic association with legumes, clover, alfalfa, and
peanuts
o Converts atmospheric N2 into ammonia
o Plant provides energy, bacteria provide N
 Endergonic: requires 16 ATP
o Nitrifers convert some of NH3 to NO2- and NO3Nitrogen fixation: the hard way
 Haber process
o Reaction of N and H using an iron catalyst
o Produces ammonia (NH3)
 Energetically expensive
o Use energy from fossil fuels and hydrocarbons
o 30% agricultural energy use – fertilizer production
 Fertilizer: human additions to soil
o Sustains 1/3 of earth’s population
o Also creates excessive runoff
 Figure 57.4
Nitrogen runoff: effects
 Figure 57.7
 Eutrophication results from over abundance of nutrients in the water
o Fertilizer run off is a main cause
o Algal bloom results in wild O2 fluctuations
o Toxic byproducts from some algae
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Dead zone: hypoxic (low oxygen) areas
o No marine life due to low oxygen
At least 170 dead zones around the world
o Range in size: 1 miles2 to over 6,000 miles2
Phosphorous
 P does not cycle through atmosphere
 Free P (PO43-) is bioavaliable in soil/sediment
 Uptake by plants – enters food chain
 Returns to soil/sediment by decomposition
 P can be a limiting nutrient
o Precipitates with Ca2+ and Mg2+ and forms nutrients
o Only available now with erosion/uphearal – slow!
o PO43- easily washed away
o Added to soil as fertilizer/pesticides
o 3.5 million tons/year enter ocean as waste
 Figure 57.5
Sulfur
 Sulfur not a limiting nutrient
o Organisms require only small amount
 Sulfur comes to living systems from airborne particles
o From volcanic activity
o Reaches living systems with rain
 Also found in coal and oil deposits
o High sulfur coal is an environmental problem
o Burning produces acid rain
Ecosystem services-1
 Natural ecosystems provide essential nutrients to living organisms
 What else do they do?
o Maintain biodiversity
 Nature’s pharmacy:
 9 of the top 10 drugs are natural plant products
 118 of the top 150 drugs come from nature
 Food source for humans (fisheries)
o Detoxify and decompose wastes
o Purify air and water
Ecosystem services-2
 What else do they do?
o Mitigate droughts and floods
o MRGO
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Moderate weather extremes
o Wind and evaporative cooling from oceans resists global
warming
Maintain wind and weather patterns
Pollination
o 1/3 of food supply in USA is naturally pollinated
o 100,000 animals provide free pollination
The value of ecosystem services
 Aesthetic value
 The cost of replacing ecosystem services
o Services poorly understood, undiscovered
o Duplicating ecosystem services
o Ecosystem services valuation and the market
o Policies encourage conversation of ecosystems to uses that
are traded at market