Chapter 7: Environmental
Systems and Ecosystem Ecology
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Environmental Systems
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community ecology (different species)
ecosystem level (living and non-living)
environmental systems
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solar radiation
geothermal activity
organism's metabolism
human activity
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pollution
Feedback
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Input: parts of a system that causes the
condition observed
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freshwater
sediments
nutrients
pollution
Output: products obtained from the system
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matter and energy in the form of fish/shellfish
Feedback loop
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when the output of a system can become the input
Negative feedback loop: input and output neutralize
each other by dynamic equilibrium resulting in
homeostasis (stabilized)
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thirst and drinking
Positive feedback loop: drive the ecosystem to one
of the extremes. Rare in nature but common when
humans alter the environment
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erosion
Dead Zone
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area in which oxygen depletion is evident (hypoxia)
normal oxygenated water has 10ppm
depletion is 2ppm or less
below 1.5ppm most organisms die
caused by several factors
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urban runoff
fertilizers
municipal sewage
industrial discharges
fossil fuel emissions
Types of Environmental Systems
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lithosphere (rock and sediment)
atmosphere (air)
hydrosphere (water systems)
biosphere (biotic and abiotic)
they overlap in some way (Ecosystems)
Ecosystems
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interaction of living and non-living
components
energy (food) is converted into biomass
(growth and repair)
nutrients can limit productivity
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too much nitrogen causes dead zone in the gulf
too much phosphorus causes dead zones in fresh
water ponds and lakes
iron seems to be the factor in open ocean waters
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Productivity
Primary Productivity Worldwide
grams of Carbon per meter squared per year
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Ecosystems Integration
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from small (simple pond) to large scale
(biosphere)
adjacent ecosystems may share components
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frogs develop in ponds, live in land and reproduce
in pond
salmon lives in the ocean but breeds in
freshwater
these areas where ecosystems meet are known
as ecotones
Landscape Ecology
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study of different ecosystems that may affect
abundance, distribution and interaction of organisms
consists of patches and these can be of different
scales
subpopulations can live in different patches
if a species move among patches to mate it is called
a metapopulation
metapopulation is used to study loss, protection and
restoration of biodiversity
5 ecosystems shown in large patches: 3 terrestrial, a marsh and a river
A corridor is shown between the marsh and the forest
Ecotone is shown between the grassland and forest showing patches in a smaller scale
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Geographic Information System (GIS)
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software that takes multiple data
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geology, hydrology, vegetation, animal species,
human development
analyzes their location in the area of study
analyzes their correlation and interactions
with the other factors
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GIS integrates different features and human uses of
an area for future development
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Biochemical Cycles
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carbon cycle
nitrogen cycle
water cycle
phosphorus cycle
rock cycle
plate tectonics
Carbon Cycle
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photosynthesis: carbon is fixated in plant growth
respiration: carbon is given back to the environment
in the form of CO2
food webs: carbon is passed along
sediment storage: remains settle to the bottom of the
ocean producing fossil fuels
oceans: absorb C from air, runoffs, volcanoes, waste
and detritus of marine organisms. Ocean
acidification
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Carbon Cycle
pool size: petagram (1015g)
fluxes: petagrams of C per year
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Shifting carbon from lithosphere to
atmosphere
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producing more carbon in the air (CO2) by
combustion than what is put back in the lithosphere
carbon cycle cannot keep up
cutting down forests and burning fields converts that
carbon into CO2 releasing it to the air
1-2 billion metric tons of CO2 is unaccounted for, so it
seems it is been taken up by plants
scientists don't know what ecosystem is doing it right
now.
Phosphorus Cycle
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essential for production of DNA, RNA, ATP and other
molecules essential for life on earth
present mainly lithosphere and ocean
humans affect it by extracting it from the lithosphere
and polluting the ocean with fertilizers
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Phosphorus cycle
pool sizes: teragrams (10-12g)
fluxes: teragrams of P per year
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Nitrogen Cycle
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78% of the atmosphere mass as N2
essential ingredient for DNA and RNA
essential for plant growth
N2 is inert but once it transforms into NH3 (ammonia)
or NH4+ (ammonium), it becomes "fixed"
fixed molecules can be taken by plants (nitrogen
fixation)
nitrifying bacteria- puts nitrogen back in soil
denitrifying bacteria- puts nitrogen back in
atmosphere
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Nitrogen Cycle
pool sizes: teragrams (10-12g) of N
fluxes: teragram of N per year
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Human Influence in Nitrogen Cycle
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excess nitrogen from agriculture practices
causes hypoxia
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dead zone in the gulf
synthetic ammonia increased food production since
1950s
factor in human population growth
nitrogen fixation has been doubled
NOx have increased in the atmosphere creating nitric
acid (acid rain) and nitric oxide (smog)
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Nitrogen Fixation since 1950
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Hydrologic Cycle
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essential for life
key role in every cycle already studied
97% ocean, 3% fresh water
carries nutrients
carries sediments
distributes pollutants
evaporation, precipitation, groundwater
Forms of Fresh Water
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vapor
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liquid
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evaporation
transpiration
precipitation
runoff
surface water (lakes, rivers)
groundwater
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aquifers
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Hydrologic Cycle
pool size: cubic kilometers (km3)
fluxes: km3 per year
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Impacts on Hydrologic Cycle
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dams increase evaporation
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dams alter vegetation
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Edwards aquifer
pollutants present in water
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Rio Grande
lower water tables
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Colorado river dams opening
agricultural fields decrease water level in rivers and streams
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lake Mead levels
Rio Grande and aquifers
conflicts for water
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Rio Grande delta, Colorado River
Geological Systems
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very slow process
rock cycle
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igneous rock
sedimentary rock
metamorphic rock
Igneous Rock
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form from magma when it cools down
it formes intrusive rocks
multicolored
formed by different similar minerals
metamorphic and sedimentary
granite is a good example
Sedimentary Rock
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formed by sediments and dissolved minerals
weight and pressure aids its formation
minerals act like glue
metamorphic and igneous
fossils and limestone
Metamorphic Rock
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changes form due to geological forces
temperature and pressure
sedimentary and igneous rock
marble
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Tectonic Plates
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Plate Boundaries
THE END
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