3-4 Ecosystem Cycles

Concept to UnderstandMatter, in the form of nutrients, cycles within and among ecosystems and in the biosphere, and human activities are altering these nutrient cycles.

Nutrient Cycles

Driven by solar energy and gravity Reservoirs – storage sites where nutrients accumulate and remain there for some time

Connect all organisms through time

Nutrient Cycles - Water, Carbon, Nitrogen

Hydrologic (Water) Cycle Water cycle is powered by the sun 1. Evaporation 2. Transpiration - evaporates from plant

surfaces 3. Condenses (in atmosphere) 4. Precipitation

Hydrologic Cycle

Water vapor in the atmosphere comes from the oceans

84% Over land, ???% of water reaching the

atmosphere comes from transpiration 90% Only 0.024% of water is available for human

use (too salty, ice, too deep underground)

Animation: Hydrologic Cycle

Increasedfloodingfrom wetlanddestruction

Condensation

Evaporationfrom ocean

Climatechange

Infiltrationand percolationinto aquifer

Condensation

Ocean

Lakes andreservoirs

Ice andsnow

Surfacerunoff

Surface runoff

Aquiferdepletion fromoverpumping

Pointsourcepollution

Reduced recharge ofaquifers and floodingfrom covering land with crops and buildings

Groundwatermovement (slow)

Runoff

Precipitationto land

Precipitationto ocean

Transpirationfrom plants

Evaporationfrom land

Fig. 3-12, p. 49

Processes

Processes affected by humans

Reservoir

Pathway affected by humans

Natural pathway

Carbon CycleCarbon – basic building block of organic molecules

(carbohydrates, fats, protein, DNA)Carbon dioxide (CO2) also controls warming and

cooling of the Earth.

Carbon CycleMajor cycle processesPhotosynthesis – remove from air make sugarsAerobic respiration – release CO2 into air Burning Fossil fuels add CO2 to the atmosphere

and contribute to global warming

Animation: Carbon Cycle

Respiration

Forest fires

Deforestation

Diffusion

Carbon dioxidedissolved in

ocean

Carbonin limestone or

dolomite sediments

Marine food websProducers, consumers,

decomposers

Transportation

Carbon dioxide

in atmosphere

Carbonin animals(consumer

s)

Plants(producer

s)

Animals(consumer

s)

Decomposition

Respiration

Compaction

Carbonin fossil

fuels

Carbonin plants(producer

s)

Burningfossil fuels

Photosynthesis

Fig. 3-13, p. 51

Processes

Reservoir

Pathway affected by humans

Natural pathway

Nitrogen CycleNitrogen- needed for proteins and DNA

Multicellular plants and animals cannot utilize atmospheric nitrogen gas (N2)

So how do we get Nitrogen?

Eating other organisms

Nitrogen CycleNitrogen fixation- lightning, some bacteria, and legumes (beans) (convert N to ammonia then Nitrate)

Nitrate is fertilizer

Nitrogen CycleAdded to soil by farmers – runs off

causing problems for local streams or lakes

Nitrogenin atmosphere

Nitrogenloss to deepocean sediments

Nitrogen oxidesfrom burning fuel

Nitratesfrom fertilizer

runoff anddecomposition

Nitrogenin oceansediments Ammonia

in soil

Volcanicactivity

Electricalstorms Nitrogen

in animals(consumers)

Bacteria

Nitratein soil

Nitrogenin plants

(producers)

Nitrificationby bacteria

Denitrificationby bacteria

Uptake by plantsDecomposition

Fig. 3-14, p. 52

Processes

Reservoir

Pathway affected by humans

Natural pathway

Animation: Nitrogen Cycle