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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