Chapter 50

An Introduction to Ecology and the Biosphere

• Ecology-the scientific study of the interactions between organisms and the environment

• Population- a group of individuals of the same species living in an area

• Community- a group of populations of different species in an area

• Ecosystem- the community of organisms in an area and the physical factors they interact with

• Landscape- a mosaic of connected ecosystems

• Biosphere- the global ecosystem, the sum of all the planet’s ecosystems

Organismalecology

Populationecology

Communityecology

Ecosystemecology

Landscapeecology

Globalecology

Rachel Carson is credited with starting the modern environmental movement with the publication of Silent Spring in 1962

Kangaroos/km2

0–0.10.1–11–55–1010–20> 20Limits ofdistribution

Dispersal- movement of individuals away from centers of high population density or from their area of origin.

Current

1966

1970

1965 1960

19611958

1951

19431937

1956

1970

Dispersal of the cattle egret in the Americas

Biotic Factors- affect the distribution of organisms include: interactions with other species, predation, and competition

Abiotic Factors- temperature, water, salinity, sunlight, wind, and rocks and soil

Low angle of incoming sunlight

Sun directly overhead at equinoxes

Low angle of incoming sunlight

Atmosphere90ºS (South Pole)60ºS

30ºS

23.5ºS (Tropic ofCapricorn)

0º (equator)

30ºN

60ºN

23.5ºN (Tropic ofCancer)

90ºN (North Pole)

March equinox

60ºN30ºN

0º (equator)

30ºSJune solstice

Constant tiltof 23.5º

September equinox

December solstice

Warm airover land rises.1

23

4

Air cools athigh elevation.

Cool air over watermoves inland, replacingrising warm air over land.

Coolerair sinksover water.

Descendingdry airabsorbsmoisture

Descendingdry airabsorbsmoisture

Ascendingmoist airreleasesmoisture

Aridzone

Aridzone

Tropics30º 23.5º 0º 23.5º 30º

60ºN

30ºN

0º(equator)

30ºS

60ºS

0º(equator)

30ºS

60ºS66.5ºS(Antarctic Circle)

30ºN

66.5ºN(Arctic Circle)

60ºNWesterlies

Northeast tradesDoldrums

Southeast trades

Westerlies

Labradorcurrent

Gulfstream

Equator

Cold water

Warm water

Winddirection

Mountainrange

Leeward sideof mountain

Ocean

Aquatic Biomes

• Photic zone- has sufficient light for photosynthesis

• Aphotic zone- receives little light

• Benthic zone- organic and inorganic sediment at the bottom of all aquatic zones

• Abyssal zone- a depth of 2,000 to 6,000 m

Littoralzone Limnetic

zone

Photiczone

PelagiczoneBenthic

zone Aphoticzone

(a) Zonation in a lake

(b) Marine zonation

2,000–6,000 mAbyssal zone

Benthiczone

Aphoticzone

Pelagiczone

Continentalshelf

200 mPhotic zone

0

Oceanic zoneNeritic zone

Intertidal zone

Winter

0º2º

4º4º

4º4ºC

Spring

4º4º

4º4ºC

4º4º

ThermoclineTurnoverSummer

8º6º

5º4ºC

18º20º

Thermocline

22º

Autumn

4º4º

4º4ºC

4º4º

Aquatic Biomes• Major aquatic biomes can be characterized by

their physical environment, chemical environment, geological features, photosynthetic organisms, and heterotrophs

An oligotrophic lake in GrandTeton National Park, Wyoming

Oligotrophic lakes are nutrient-poor and generally oxygen-rich

A eutrophic lake in theOkavango Delta, Botswana

Eutrophic lakes are nutrient-rich and often depleted of oxygen if ice covered in winter

Okefenokee National Wetland Reserve in Georgia

Wetlands -inundated by water at least some of the time

A headwater stream in the GreatSmoky Mountains

The Mississippi River far fromits headwaters

Streams and Rivers - the most prominent physical characteristic is current

An estuary in a low coastal plain of Georgia

Estuary- transition area between river and sea, salinity varies, nutrient rich and highly productive

Rocky intertidal zone on the Oregon coast

Intertidal Zones- periodically submerged and exposed by the tides, variations in temperature, salinity, wave action forces

Open ocean off the island of Hawaii

Oceanic Pelagic Zone- open blue water, constantly mixed by wind-driven oceanic currents, covers approximately 70% of Earth’s surface, phytoplankton and zooplankton

A coral reef in the Red Sea

Coral Reefs- formed from the calcium carbonate skeletons of corals

Tropical forest

Savanna

Desert

Chaparral

TemperategrasslandTemperatebroadleaf forestNorthernconiferous forestTundra

High mountains

Polar ice

30ºNTropic ofCancerEquatorTropic ofCapricorn

30ºS

Tropical forestTemperate grasslandDesert

Temperatebroadleafforest

NorthernconiferousforestArctic andalpinetundraA

nnua

l mea

n te

mpe

ratu

re (º

C)

Annual mean precipitation (cm)

30

15

0

0–15

100 200 300 400

Terrestrial Biomes• Terrestrial biomes can be characterized by

distribution, precipitation, temperature, plants, and animals

A tropical rain forest in Borneo

Tropical Forest tropical rain forests- rainfall

is relatively constanttropical dry forests-

precipitation is highly seasonal

A desert in the southwesternUnited States

Desert- Precipitation is low and variable. Temperature is hot or cold. Plants adapted for heat and desiccation tolerance, water storage, and reduced leaf surface area. Many animals are nocturnal.

A savanna in Kenya

Savanna- precipitation and temperature are seasonal. Grasses make up most of the ground cover.

An area of chaparralin California

Chaparral- climate is highly seasonal, cool and rainy winters and hot dry summers. Dominated by shrubs, small trees, grasses, and herbs; many plants are adapted to fire and drought.

Sheyenne National Grasslandin North Dakota

Temperate Grassland- winters are cold and dry, while summers are wet and hot. Dominant plants and grasses are adapted to droughts and fire.

Rocky Mountain National Parkin Colorado

Northern Coniferous Forest (Taiga)- winters are cold and long while summers may be hot.

Great Smoky MountainsNational Park in North Carolina

Temperate Broadleaf Forest- winters are cool, summers are hot and humid; significant precipitation falls year round as rain and snow. Vertical layers of deciduous trees or eucalyptus

Denali National Park, Alaska,in autumn

Tundra- covers expansive areas of the Arctic and on high mountaintops at all latitudes. Winters are long and cold while summers are relatively cool; precipitation varies

Permafrost- a permanently frozen layer of soil, prevents water infiltration. Vegetation: mosses, grasses, dwarf shrubs and trees, and lichen

Sierra NevadaGreat Basin

Plateau

Mea

n he

ight

(cm

)A

ltitu

de (m

)

Seed collection sites

100

50

0

3,000

2,000

1,000

0