Ecosystems

Page
5

All elements cycle between organic and inorganic reservoirs.

Slide 28

Nutrient Cycling

Reservoir A

Reservoir B

Organic

materials

available

as nutrients

Fossilization

Organic

materials

unavailable

as nutrients

Reservoir D

Reservoir C

Coal, oil,

peat

Living

organisms,

detritus

Burning

of fossil fuels

Respiration,

decomposition,

excretion

Assimilation,

photosynthesis

Inorganic

materials

available

as nutrients

Inorganic

materials

unavailable

as nutrients

Atmosphere,soil, water

Minerals

in rocks

Weathering,

erosion

Formation of

sedimentary rock

Slide 29

In studying cycling of water, carbon, nitrogen, and phosphorus, ecologists focus on four factors:

Each chemical’s biological importance

Forms in which each chemical is available or used by organisms

Major reservoirs for each chemical

Key processes driving movement of each chemical through its cycle.

Slide 30

The Water Cycle

Water is essential to all organisms.

97% of the biosphere’s water is contained in the oceans, 2% is in glaciers and polar ice caps, and 1% is in lakes, rivers, and groundwater.

Water moves by the processes of evaporation, transpiration, condensation, precipitation, and movement through surface and groundwater.

Slide 31

Nutrient Cycles: Water Cycle

Precipitation

over land

Transport

over land

Solar energy

Net movement of

water vapor by wind

Evaporation

from ocean

Percolation

through

soil

Evapotranspiration

from land

Runoff and

groundwater

Precipitation

over ocean

Slide 32

The Carbon Cycle

Carbon-based organic molecules are essential to all organisms.

Carbon reservoirs include fossil fuels, soils and sediments, solutes in oceans, plant and animal biomass, and the atmosphere.

CO2 is taken up and released through photosynthesis and respiration; additionally, volcanoes and the burning of fossil fuels contribute CO2 to the atmosphere.

Slide 33

Nutrient Cycles: Carbon Cycle

Higher-level

consumers

Primary

consumers

Detritus

Burning of

fossil fuels

and wood

Phyto-

plankton

Cellular

respiration

Photo-

synthesis

Photosynthesis

Carbon compounds

in water

Decomposition