Ecology & the BiosphereEcology & the Biosphere

Chapter 18Chapter 18

BiomesBiomes

• Major terrestrial or aquatic life zone

• Aquatic biomes– Occupy roughly 75% of Earth’s surface – Freshwater– Marine

• Terrestrial biomes– Classified based on vegetation type

Aquatic - FreshwaterAquatic - Freshwater• Typically have a salt concentration of less than 1% • Standing water

– includes lakes and ponds

• Flowing water– rivers and streams

• Wetlands• Cover less than 1% of Earth • Contain a mere 0.01% of its water • Harbor about 6% of all described species• Are used for drinking water, crop irrigation, sanitation, and

industry

Aphoticzone

Photiczone

Benthic realm

Aquatic - MarineAquatic - Marine

• Typically have a salt concentration around 3%

• Oceans• Intertidal zones• Coral reefs• Estuaries

High tide

Benthic realm(seafloor from continentalshelf to deep-sea bottom)

Pelagic realm (open water) Low tide

Oarweed (to 2 m) Sea star

(to 33 cm)

Intertidalzone

Continentalshelf

Sea pen(to 45 cm)

Sea spider(1–90 cm)

Brittlestar

(to 60 cm) Glass sponge

(to 1.8 m)

Sponges(1 cm–1 m)

Brain coral(to 1.8 m) Phyto-

planktonZoo-

plankton

Man-of-war(to 50 m long)

Blue shark (to 2 m)

Sperm whale(10–20 cm)

Hatchet fish(2–60 cm)

Rat-tail fish(to 80 cm)

Octopus(to 10 m)

Gulper eel(to 180 cm)

Turtle(60–180 cm)

Sea cucumber (to 40 cm)

Tripod fish (to 30 cm)

Anglerfish(45 cm–2 m)

Photiczone

Aphoticzone

6,000–10,000 m

1,000–4,000 m

200 m

No light

“Twilight”

TerrestrialTerrestrial• Tropical Forest• Savanna• Desert• Chaparral• Temperate Grassland• Temperate broadleaf forest• Coniferous forest• Tundra• Polar ice

Temperate broadleaf forestConiferous forestArctic tundraHigh mountains (coniferous forest andalpine tundra)Polar ice

Tropical forest

Temperate grasslandChaparralDesertSavanna

Key

Tropic of Capricorn

30º N

Equator

30º S

Tropic of Cancer

Figure 18.27

Tropical Rainforest Tropical Rainforest

• occur in equatorial areas

• temperature is warm• days are 11–12 hours

long year-round• 200-400 cm rain

– 79-157 inches

SavannasSavannas

• dominated by grasses and scattered trees

• warm year-round• Experience 30-50 cm

rainfall – 12–20 inches – dramatic seasonal

variation

DesertsDeserts

• driest of all biomes• Less than 30 cm

– 12 inches

• May be very hot or very cold– 140 to -22 F

Temperate GrasslandsTemperate Grasslands• mostly treeless• 25-75 cm rain per

year– 10–30 inches

• Experience frequent droughts and fires

• characterized by grazers including bison and pronghorn in North America

Temperate Broadleaf ForestTemperate Broadleaf Forest

• Occurs throughout midlatitudes – sufficient moisture to

support the growth of large trees

• 75-150 cm rain – 30-60 inches

• Includes dense stands of deciduous trees in the Northern Hemisphere

Coniferous ForestConiferous Forest

• “Temperate rainforest”• dominated by cone-

bearing evergreen trees

• Includes the taiga– largest terrestrial biome

on Earth

TundraTundra

• Covers expansive areas of the Arctic between the taiga and polar ice

• characterized by– Permafrost

• permanently frozen subsoil

– Bitterly cold temperatures– High winds

Polar icePolar ice

• high latitudes – north of the arctic

tundra in the northern hemisphere

– Antarctica in the southern hemisphere

• Only a small portion of these land masses is free of ice or snow– Even in summer!