Chapter 7: Environmental Systems and Ecosystem Ecology
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Environmental Systems
community ecology (different species) ecosystem level (living and non-living) environmental systems
– solar radiation– geothermal activity– organism's metabolism– human activity
pollution
Feedback
Input: parts of a system that causes the condition observed– freshwater– sediments– nutrients– pollution
Output: products obtained from the system– matter and energy in the form of fish/shellfish
Feedback loop
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)
– thirst and drinking
Positive feedback loop: drive the ecosystem to one of the extremes. Rare in nature but common when humans alter the environment
– erosion
Dead Zone
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
– urban runoff– fertilizers– municipal sewage– industrial discharges– fossil fuel emissions
Types of Environmental Systems
lithosphere (rock and sediment) atmosphere (air) hydrosphere (water systems) biosphere (biotic and abiotic) they overlap in some way (Ecosystems)
Ecosystems
interaction of living and non-living components
energy (food) is converted into biomass (growth and repair)
nutrients can limit productivity– 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
Primary Productivity Worldwide
Productivity
grams of Carbon per meter squared per year
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Ecosystems Integration
from small (simple pond) to large scale (biosphere)
adjacent ecosystems may share components– 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
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)
software that takes multiple data– geology, hydrology, vegetation, animal species,
human development
analyzes their location in the area of study analyzes their correlation and interactions
with the other factors
GIS integrates different features and human uses of an area for future development
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Biochemical Cycles
carbon cycle nitrogen cycle water cycle phosphorus cycle rock cycle plate tectonics
Carbon Cycle
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
Carbon Cycle pool size: petagram (1015g) fluxes: petagrams of C per year
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Shifting carbon from lithosphere to atmosphere
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
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
Phosphorus cyclepool sizes: teragrams (10-12g)fluxes: teragrams of P per year
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Nitrogen Cycle
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
Nitrogen Cycle pool sizes: teragrams (10-12g) of Nfluxes: teragram of N per year
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Human Influence in Nitrogen Cycle
excess nitrogen from agriculture practices causes hypoxia
– 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)
Nitrogen Fixation since 1950
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Hydrologic Cycle
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
vapor– evaporation– transpiration
liquid– precipitation– runoff– surface water (lakes, rivers)
groundwater– aquifers
Hydrologic Cyclepool size: cubic kilometers (km3)fluxes: km3 per year
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Impacts on Hydrologic Cycle
dams increase evaporation– lake Mead levels
dams alter vegetation– Colorado river dams opening
agricultural fields decrease water level in rivers and streams– Rio Grande
lower water tables– Edwards aquifer
pollutants present in water– Rio Grande and aquifers
conflicts for water– Rio Grande delta, Colorado River
Geological Systems
very slow process rock cycle
– igneous rock– sedimentary rock– metamorphic rock
Igneous Rock
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
formed by sediments and dissolved minerals weight and pressure aids its formation minerals act like glue metamorphic and igneous fossils and limestone
Metamorphic Rock
changes form due to geological forces temperature and pressure sedimentary and igneous rock marble
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Plate Boundaries
THE END
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