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Chapter 35 Major Ecosystems of the Biosphere

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

35.1 Climate and the Biosphere

• Climate

– Prevailing weather conditions in a particular

region

– Dictated by temperature and rainfall,

influenced by following factors:

– Variations in solar radiation distribution

– Other effects – topography, proximity to water

bodies


• Effect of Solar Radiation

– The sun’s rays are more direct at the equator

and more spread out nearing the poles

• Makes tropical regions warmer than temperate

regions

– The Earth is on a slight tilt

• As the Earth orbits, different areas are tilted toward

or away from the sun – determines seasons

equator

equator

North

Pole

South

Pole



23

sun

Summer solstice

Northern Hemisphere

tilts toward sun, June

Vernal equinox

Sun aims directly

at equator, March Winter solstice

Northern Hemisphere

tilts away from sun,

December

Autumnal equinox

Sun aims directly

at equator, September


• Effect of Solar Radiation

– The flow of warm and cold air form three large

circulation patterns in each hemisphere

– The direction in which the air rises and cools

determines the direction of the wind

• Northern Hemisphere: Large scale winds

generally move clockwise, in the southern

hemisphere they move counterclockwise

0°

Ascending

moist air

cools and

loses moisture.

Descending

dry air warms

and retains

moisture.

30°S

60°S

30°N

60°N

northeast

winds



• Other Effects

– Topography - physical features of land

• Mountains

– The windward side receives more rain than the

leeward side

– Create a rain shadow on leeward side

– As air blows up the mountain, it rises and cools

– As air descends the other side of the mountain,

it picks up moisture and produces clear

weather

Formation of a Rain Shadow Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

condensation

rain shadow

dry air

windward side leeward side


• Other Effects

– Topography • Monsoon Climate in southern Asia

– Land heats more rapidly than the waters of the

Indian Ocean during spring

– Gigantic circulation of air: warm air rises over

the land, and cooler wet air comes in off the

ocean to replace it wet ocean winds blow

onshore for almost half the year

– Rainfall heavin on the windward side of hills

– Pattern reversed in November


• Other Effects

– Topography

• Lake Effect

– In the winter, arctic winds blowing over the

Great Lakes become warm and moisture-laden

– When these winds rise and lose their moisture,

snow begins to fall

– Buffalo, New York, gets heavy snowfall due to

lake effect ~90-140 days

35.2 Terrestrial Ecosystems

• Biome - major type of terrestrial

ecosystem

– Depends on latitude, longitude and rainfall

Characteristic mix of plants and animals

adapted to live there

– Forms particular pattern when plotted

according to their mean annual temperature

and mean annual precipitation


savanna

grassland

temperate

deciduous

forest

taiga

tundra

Arctic-

alpine

cold

temperate

temperate

rain forest

tropical

rain forest

tropical

seasonal

forest

Mean Annual Precipitation (cm)

desert

–15

–10

–5

0

5

10

15

20

25

30 50 100 150 200 250 300 350 400 450

warm

temperate

Mean

An

nu

al

Tem

pera

ture

(°C

)

desert

semidesert

savanna

temperate grassland

shrubland

tropical rain forest

tropical seasonal forest

tropical deciduous forest

temperate rain forest

temperate deciduous forest

mountain zone

taiga

tundra

polar ice



• Distribution of the biomes and their

corresponding communities of organisms

is determined by:

– Differences in climate due to the distribution

of solar radiation

– Water

– Defining topographical features

• Both latitude and altitude are responsible

for temperature gradients

ice

tundra ice

Increasing Latitude

alpine

tundra

montane

coniferous

forest

deciduous

forest

tropical

forest

temperate

deciduous

forest coniferous

forest

Incre

asin

g A

ltit

ud

e



• Tundra

– Encircles Arctic region south of ice-covered polar

seas in the Northern Hemisphere

– Very cold and dark most of the year—short growing

season, precipitation is minimal

– Permafrost prevents water drainage

– Vegetation

• Lichens, short grasses, dwarf shrubs

– Animals

• Caribou, reindeer, wolves, polar bears

Tundra


• Coniferous Forests

– Taiga

• Northern part of North America and Eurasia

• Trees are well adapted to the cold climate

– Needles (reduced leaves), thick bark

• Vegetation

– Cone-bearing trees: pine, firs, spruce

– Mosses, lichens

• Animals

– Bears, deer, moose, beavers, wolves, birds


• Coniferous Forests

– Montane coniferous forest - near

mountaintops

• Wolverine and mountain lion

– Temperate Rainforest

• Western coast of the United States and Canada

• Plentiful rainfall and rich soil have produced some

of the tallest conifer trees ever known

• Old-growth forest, trees are >150 years old- 800

Coniferous Forest


• Temperate Deciduous Forests – Eastern North America, Europe, Eastern Asia

– Well-defined seasons, long growing season, relatively

high precipitation

– Vegetation

• Oak, beech, maple, and other broad-leaf deciduous trees

• Tall trees form canopy, shrubs and shorter trees below

• Lichens, ferns on forest floor

– Animals

• Squirrels, rabbits, chipmunks, and other small herbivores

• Beaver, red foxes, deer, and black bears

Temperate Deciduous Forests


• Tropical Forests

– South America, Africa, Indo-Malayan region

– Weather is always warm, abundant rainfall

– Biome with the greatest diversity of species of

plants and animals

– Complex structure, many levels of life

• Many animals live in the trees

• Epiphytes are plants that grow on other plants but

usually have roots of their own that absorb mineral

and moisture leached from the canopy

Tropical Rain Forests


• Shrublands

– Tend to occur along coasts that have dry

summers and receive most of their rainfall in

winter

– Shrubs with waxy leaves, adapted to arid

conditions

• Regrow after a fire

– Animals include coyotes, jackrabbits, gophers

and other rodents

Shrublands


• Grasslands

– Rainfall is greater than 25 cm/year but not

enough to support trees

– Grasses well adapted to changing

environment

– Russian steppes

– North American prairies

– African savanna

– Animals include bison and small mammals

The Prairie

The Savanna


• Deserts

– Usually found at latitudes of about 30°, in both

the Northern and Southern Hemispheres

– Annual rainfall is less than 25 cm

– Hot days and cold nights

– Most deserts have a variety of plants

• Succulent cacti and nonsucculent sagebrush

– Animals

• Many are burrowing animals

• Nocturnal to avoid heat

Deserts

35.3 Aquatic Ecosystems

• Two Main Types

– Freshwater (inland) ex. lakes

– Saltwater (usually marine) ex. oceans

• Brackish water is a mixture of fresh and salt water

– Coastal Ecosystems


• Lakes

– Freshwater

– Classified by their

nutrient abundance

• Oligotrophic

(nutrient-poor)

• Eutrophic (nutrient-

rich)

• In the temperate zone, deep lakes

are stratified in the summer and

winter

• Vertical stratification and seasonal

change of temperatures in a lake

basin influence the seasonal

distribution of fish and other aquatic

life


35.3 Aquatic Ecosystems Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Summer stratification

Fall overturn Spring overturn

wind

wind

wind

wind

ice

epilimnion 24–25°C

thermocline 13–18°C

hypolimnion

5–8°C

2–3°C

most of lake

4°C

Winter stratification

Zones of a Lake Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

surface organisms

fishes

insect larvae

phytoplankton

zooplankton

water strider

northern pike

clinging

organisms

Benthic

Zone

Littoral

Zone

Limnetic

Zone

Profundal

Zone

bottom-dwelling

organisms

(pike): © Robert Maier/Animals Animals; (water strider): © Frank Greenaway/Getty Images


• Coastal Ecosystems

– Estuaries

• Partially enclosed body of water where fresh and

salt water mix

• Coastal bays, tidal marshes, and lagoons

• “Nurseries” of the sea

– Abundance of nutrients

– Half of all marine fish mature in estuaries

– Feeding grounds of many birds, fish, shellfish

Estuary Structure and Function

white shrimp

phytoplankton

freshwater

input freshwater

input

spawning

and nursery spawning

and nursery

ocean

water


(shrimp): © Ken Lucas/Ardea London Limited; (snails): © Fred Whitehead/Animals Animals

Marine snails, at the base of salt

marsh cordgrass, feed on algae.


• Coastal Ecosystems

– Seashores

• Littoral zone - between high and low tidal

marks – divided into 3 zones

• Rocky or sandy beaches

– Animals must burrow on sandy beaches

• Clams, crabs, sand (ghost) shrimp,

sandhoppers

Seashores


• Oceans

– Ocean play a major role in redistributing heat in the biosphere

– Major influence on wind patterns

• Northern hemisphere – Currents circulate clockwise

• Gulf stream brings tropical Carribean water to east coast of North America and higher latitudes of western Europe


• Oceans

– Ocean currents influence climate

• Southern hemisphere – Currents circulate counterclockwise

• Humboldt Current: circulates cold, nutrient-rich water along west coast of South America

Upwelling: cold offshore winds cause nutrient-rich waters to rise and displace warm, nutrient-depleted water


• Oceans

– Pelagic Division (open waters)

• Neritic Province – sunlight and inorganic nutrients

– Coral reefs

• Oceanic Province – lacks nutrients

– Benthic Division (ocean floor)

• Sublittoral zone – continental shelf ex. seaweeds

• Bathyal zone – continental slope ex. Sea urchins

• Abyssal zone – abyssal plain ex. Sea cucumbers


Neritic Province

Oceanic Province

Pelagic Division littoral zone high-tide mark

low-tide mark

120 m

1,200 m

3,000 m

4,000 m

abyssal plain

abyssal zone

bathypelagic zone

mesopelagic zone

epipelagic zone Benthic

Division

depth

(meters)


Me

so

pe

lag

ic Z

on

e

(12

0 –

1,2

00

m)

phytoplankton zooplankton

sea turtle

dolphin shark

jellyfish

ocean bonito

mackerel

squid

tuna

prawn

midshipman

viperfish

hagfish anglerfish

glass sponges

sea cucumber

brittle stars

gulper

barracuda

baleen whale

Ep

ipe

lag

ic Z

on

e

(0 –

12

0 m

)

Bath

yp

ela

gic

Zo

ne

(1,2

00

– 3

,00

0 m

)

Ab

ys

sa

l Z

on

e

(3,0

00

m –

bo

tto

m)

deep-sea

shrimp

tripod

fish

sperm

whale

giant

squid

lantern

fish

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