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1

The Biosphere

Chapter 58

Effects of Sun, Wind, Water

• Biosphere: includes all living

communities on Earth

• Global patterns of life on Earth are

influenced by

1. The amount of solar radiation that

reaches different areas

2. Patterns of global atmospheric

circulation which influence oceanic

circulation

2

Biomes

• Biomes: a major type of ecosystem on

land

• Each biome has a characteristic

appearance

– Defined largely by sets of regional

climatic conditions

• Biomes are named according to their

vegetational structures

• 8 principle biomes with 6 others

3

4

Distributions of biomes

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

taiga temperate evergreen forest

temperate deciduous foresttundra

polar ice mountain zone

tropical rain forest

tropical monsoon forest

warm, moist evergreen forest

savanna

temperate grassland desert

semidesertchaparral

5

Biomes

Predictors of biome distribution

Temperature and precipitation


Sem

idesert

450400350300250200

Mean Annual Precipitation (cm)

15010050

30

25

20

15

10

5

0

–5

–10

–15

Mean

An

nu

al

Tem

pera

ture

(°

C) Hot

desert SavannaTropical

rainforest

Temperate

evergreen

forest

Taiga

Tundra

Temperate

grassland Temperate

deciduous

forest

6

The correlations of primary productivity

with precipitation and temperature


a.

b.

500 100 200

Precipitation (cm/year)

300 400

500

1000

1500

2000

2500

–10 0–5 5 1510 2520 30

500

0

1000

1500

2000

2500

Temperature (C)

Pro

du

cti

vit

y (

g/m

2/y

ear)

Pro

du

cti

vit

y (

g/m

2/y

ear)

7

Biomes

• Tropical rain forests

– 140–450 cm rain/yr

– Richest ecosystems

on land

– High temperature

and high rainfall

– Very high diversity:

1,200 species of

butterflies in a single

square mile

8

• Savanna

– 50–125 cm rainfall/yr

– Tropical or subtropical grasslands

– Occur as a transition ecosystem

between tropical rainforests and deserts

– Serengeti of East Africa

Biomes

9

• Deserts

– 25–40 cm rainfall/yr; unpredictable

• Plants and animals cannot depend

on any rainfall

– 30˚N and S latitudes – due to global

air circulation patterns

– Due to rain shadows

– Vegetation sparse, animals adapted

to little water availability

Biomes

10

• Temperate grasslands or prairies

– Rich soils

– Grasses with roots that penetrate deep

into the soil

– In North America converted to

agricultural use

– Adapted to periodic fire

Biomes

Biomes

• Temperate deciduous forests

– Mild but seasonal climates

(warm summers and cold

winters), plus plentiful rains

• Temperate evergreen forests

– Occur along coastlines with

temperate climates

• Taiga and tundra

– Both stretch in unbroken circles

around the entire globe

11

Freshwater Habitats

• Fresh water covers only 2% of Earth’s surface

• Life depends on oxygen availability

– Oxygen per liter is only 5% of that in the

atmosphere

– Oxygen added by photosynthesis and aeration

from the atmosphere

– Oxygen is removed by animal and detritivore

respiration, and through decaying organic matter

– Warm water holds less O2 than cooler water

12

Freshwater Habitats

• Lake and pond habitats change with water depth

– Intensity of light decreases with water depth

– Photic zone: area where light penetrates and photosynthesis is possible

– Littoral zone: shallows at edge of lake

– Aphotic (benthic) zone: below light penetration level

13

14

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

Productivity

Lake Zones and Productivity

Littoral

zone

Photic

zone

Aphotic

zone

Marine Habitats

• 71% of the Earth’s surface is covered by ocean

• Continental shelves: near coastlines, water is not especially deep

– ~ 80 km wide and 1 m to 130 m deep

• Average depth of the open ocean is 4,000–5,000 m deep

– Trenches: 11,000 m deep

• Principle primary producers are phytoplankton (single cell or colonial)

15

Marine Habitats

• Banks and coral reefs

– Banks are local shallow areas on the shelves

• Fishing grounds

– Coral reefs occur in subtropical and tropical latitudes

– Defining feature is stony corals

• Algal symbioses: cnidarians and dinoflagellates

16

Marine Habitats

• El Niño Southern Oscillation (ENSO)

– 2–7 years on an irregular and unpredictable basis

– Coastline waters become profoundly warm

– Primary productivity unusually low

– Weakening of the east-to-west Trade Winds

– Upwelling continues, but only recirculates the thick, warm surface layer

17

Marine Habitats

• El Niño can wreak havoc on ecosystems

– Plankton abundance can drop to 1/20th normal levels

– Fish stocks disappear

– Seabirds and sea lion populations crash

• On land

– Heavy rains produce abundant seeds and land birds flourish

– Increase rodent population

– Increase predator population18

19

Marine Habitats

El Niño winter


Wetter

Wetter and

cooler

Warmer

Warmer

Warmer

Warmer

Warmer

Wetter and warmer Drier

Drier

EI Niño

Sea temperature

higher than normal

Wetter and

warmer

Marine Habitats

• Deep sea: cold, dark place with

fascinating communities

– Seasonless, 2–5˚C; pressure: 400–

500 atm

• Food originates from photosynthesis in

the sunlit waters

• 99% eaten as it drifts down through the

water column

• Animals: small-bodied, thinly distributed

20

Marine HabitatsHydrothermal vent communities: thick with life

• Large-bodied animals

• Do not depend on the Sun’s energy for primary production

• Depend on sulfur-oxidizing bacteria

• Water temperature up to 350˚C


a: © Jim Church; b: © Ralph White/Corbis; b(inset): NOAA Pacific Marine

Environmental Laboratory’s Vents Program

a.

b.

21

Human Impacts: Pollution

• Human impacts can cause adverse

changes in ecosystems

• DDT: highly effective insecticide,

sprayed in United States after WWII

– DDT is oil soluble and biomagnifies in the

food chain

– Result of use

• Populations of ospreys, bald eagles, and

brown pelicans plummeted

22

23

• Biomagnification of

DDT concentrations

in the food chain

• Predatory bird

species were

affected because it

made their

eggshells so thin

that the shells broke

during incubation


DDT Concentration

25 ppm in

predatory birds

2 ppm in

large fish

0.5 ppm in

small fish

0.04 ppm in

zooplankton

0.000003 ppm

in water



• Freshwater habitats are threatened by

pollution and resource use

• Point source pollution: comes from an

identifiable location

– Factories

– Sewage-treatment plants

• Laws and technologies can be applied

because the source is known

24


• Diffuse pollution: is exemplified by eutrophication caused by excessive run-off of nitrates and phosphates

– Dissolved oxygen declines

– Fish species change, carp take the place of more desirable species

• Can originate from thousands of lawns, farms, golf clubs, etc.

• Solutions depend on public education and political action

25


• Pollution from coal burning: acid precipitation

– When coal is burned, sulfur oxide is released

– Sulfur oxide combines with water in the atmosphere to create sulfuric acid

• Mercury emitted in stack smoke is a second potential problem

– Mercury can interfere with brain

development in human fetuses and infants

26


• Acid precipitation and mercury pollution

affect freshwater ecosystems

– pH levels below 5.0, many fish

species and other aquatic animals die

or are unable to reproduce

– Mercury accumulates in the tissues of

food fish: dangerous to public health

27

28


Precipitation pH

<4.3>5.3pH values of rainwater

in the United States

29

Damage to trees by

acid precipitation at

Clingman’s Dome,

Tennessee.

30

• Terrestrial ecosystems are threatened

by deforestation

– Single greatest problem is deforestation by

cutting or burning

• An example is rainforest destruction



a. b.a: © Environmental Images/agefotostock; b: © Frans Lanting/Corbis


• Deforestation consequences

– Loss of habitat

– Major contributing factor in increased

desertification

– Loss of nutrients from soils

– Nutrient enrichment of bodies of

water downstream

– Disruption of the water cycle

– Acid rain31

32

• Overfishing of the ocean

– Single greatest problem in the ocean

realm

Poaching on

terrestrial

animals

increases

when fish

populations

decline



100

total biomass in

the ecosystem

biomass taken

by fishing

200619991992

Year

19851978

0

20

40

60

80

We

igh

t o

f F

ish

(th

ou

sa

nd

s o

f m

etr

ic t

on

s)


• Pollution effects in the ocean

– Plastic found washed up on beaches

in remote areas

– Waters are laced with toxic chemicals

– Biopsy of tissue from Arctic killer

whales reveal high levels of

pesticides and flame-retardant

chemicals

33

• Stratospheric ozone depletion

– Ozone hole: over Antarctica between

1/2 to 1/3 of original ozone

concentrations are present


34


a: NASA/Goddard Space Flight Center Scientific Visualization Studio

20112010

2009

2008

2001–2010 average

DecemberNovemberOctoberSeptemberAugust

27

24

21

18

15

12

9

6

3

0

So

uth

ern

Hem

isp

here

Ozo

ne H

ole

Are

a

(millio

ns o

f sq

uare

kilo

mete

rs)

a. b.

South

Pole


• Over United States

– Ozone concentration has been reduced by about 4%

• Stratospheric ozone is important because it absorbs UV radiation (UV-B)

• UV-B damages tissue, increases risks for

– Skin cancer: 1% drop in ozone leads to a 6% increase in skin cancer

– Detrimental to amphibians35


• Ozone depletion and CFCs: Major cause of ozone depletion are chlorine-and bromine-containing compounds in the atmosphere

• Use of CFCs are being phased out in many countries

• CFCs are chemically stable in the atmosphere for many years

• Ozone depletion will continue to occur until all of the CFCs are broken down

36

Climate Change

• CO2 and other gases in the atmosphere

maintain the Earth’s average

temperature at 25˚C higher than it

would be without these gases

• Human activities are now changing the

composition of the atmosphere;

increasing the CO2 and other gas levels

• Because of the increase, global

temperatures are increasing, causing

global warming37

38


–4.1 –0.5 –0.2 0.2 0.5 1 2 4 4.4

2011 Surface Temperature Anomalies (°C)

–2 –1–4

NASA Goddard Institute for Space Studies

Climate Change

• Based on a variety of different

scenarios, computer models predicted

that global temperatures would increase

1.1°C to 6.4°C (2.0–11.5°F) by the

end of this century

• Some countries will come out ahead,

others will come out behind

39

Climate Change

• Carbon dioxide is the major greenhouse

gas

– Other atmospheric gases also

involved

• All authorities agree that the cause of

this steady rise in atmospheric CO2 is

the burning of coal and petroleum

products by the increasing (and

increasingly energy-demanding) human

population40

41

The greenhouse effect


Year

390

380

370

360

350

340

330

320

310

1960 1970 1980 1990 2000 2010

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

–0.1

–0.2

Carb

on

Dio

xid

e C

on

ce

ntr

ati

on

(p

pm

v)

An

nu

al

Glo

ba

l Te

mp

era

ture

An

om

ali

es

(°

C)

Climate Change

• How CO2 affects temperature

– CO2 absorbs electromagnetic radiant

energy

– Earth receives radiant energy from

the Sun

– Earth also emits radiant energy

– The Earth’s temperature will be

constant only if the rates of these two

processes are equal

42

43

Climate Change

• The atmosphere allows in short wave

radiant energy from the Sun, but does

not allow the long wave radiant energy

from the Earth to escape

• This is the same principle as a

Greenhouse

Short wave – in, long wave –

cannot get out, increase in

temperature in the

greenhouse

Climate Change

• Other greenhouse gases

– Methane: 20 times the heat trapping properties of CO2, less concentration in the atmosphere, less long-lived

– Methane is produced globally in anaerobic soils and fermentation reactions of ruminant mammals

– Methane is locked up in permafrost

• Sudden release will cause large perturbation in global temperature

44

Climate Change

• Other greenhouse gases

– Nitrous oxide: agricultural use of fertilizers is the largest source

– Energy consumption

– Industrial use

• Evidence confirms global warming

– Ice free seasons 2.5 weeks longer

– Ice at the North Pole decreased

– Glaciers decreasing in size

45

46

Climate Change

Disappearing glaciers

Climate Change

• Global temperature change has affected

ecosystems in the past and is doing so

now

– Shift in species’ geographic ranges

– Migratory birds arrive earlier at their

summer breeding grounds

– Insects and amphibians breed earlier

– Wild fruit fly populations – changes in gene

frequency

– “Bleaching” of reef-building corals47

Climate Change

• Problems

– Rate of warming today is rapid

– Evolutionary adaptations for species

survival may not have time to occur

– Natural areas no longer cover the whole

landscape

– Species that shift to higher altitudes may

have reached the peak of the mountain

– Species’ habitat disappears entirely

48

Climate Change

• Effects on agriculture

– Positive: more CO2 tends to increase

growth of some crops

– Increase pollen production causing

more severe allergies

– More droughts in some regions

– Decrease in crop production in

tropical areas

49

Climate Change

• Human health

– Frequent flooding = loss of safe drinking water

• Cholera and other epidemics may occur more often

– Tropical diseases may invade nontropical countries

• Malaria

• Dengue fever

50

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