CYCLES of LIFE 28.3 How Do Nutrients Cycle Within and Among Ecosystems?

Presentation on theme: "CYCLES of LIFE 28.3 How Do Nutrients Cycle Within and Among Ecosystems?"— Presentation transcript:

Slide1

CYCLESofLIFESlide2

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

Some of the chemical building blocks of life, called

macronutrients

, are required by organisms in large quantities

Water

–

Carbon

Hydrogen

–

Oxygen

Nitrogen

–

Phosphorous

Sulfur

–

CalciumSlide3

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

Macronutrients

are required only in trace quantities

Zinc

–

Molybdenum

Iron

–

Selenium

Iodine

Nutrient cycles

, also called

biogeochemical cycles

, describe the pathways that macronutrients and micronutrients follow as they move from their major sources in the abiotic parts of ecosystems, called

reservoirs

, through living communities and back againSlide4

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The hydrologic cycle has its major reservoir in the oceans

The water cycle, or

hydrologic cycle

, is the pathway that water takes as it travels from its major reservoir—the oceans—through the atmosphere, to reservoirs in freshwater lakes, rivers, and groundwater, and then back again to the oceans Slide5

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The hydrologic cycle has its major reservoir in the oceans

(continued)

The hydrologic cycle would continue even if life on Earth disappeared because the biotic portion of ecosystems plays a small role in the hydrologic cycle

The oceans cover 70% of the Earth’s surface and contain more than 97% of Earth’s water

Solar energy evaporates water, and it comes back to Earth as precipitation Slide6

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The hydrologic cycle has its major reservoir in the oceans

(continued)

Of the water that falls on land

Some is absorbed by the roots of plants

Most evaporates from the soil, lakes, and streams

A portion runs back to the oceans

An extremely miniscule fraction is stored in the bodies of living organisms

Some enters natural underground reservoirs called

aquifersSlide7

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The hydrologic cycle has its major reservoir in the oceans

(continued)

The hydrologic cycle is crucial for terrestrial communities because it continually restores the fresh water needed for land-based life

Plant leaves can only take up carbon dioxide gas after it has dissolved in a thin layer of water coating the cells inside the leaf

The hydrologic cycle does not depend on terrestrial organisms, but they would disappear without itSlide8

reservoirs

Figure 28-6

The hydrologic cycle

reservoirs

processes

processes

precipitation

over land

water vapor in

the atmosphere

evaporation

from the land

and from the

leaves of plants

lakes and rivers

evaporation from

lakes and rivers

runoff

from rivers

and land

evaporation

from the

ocean

water in

the ocean

precipitation

over the ocean

extraction for

agriculture

groundwater,

includingaquifers

seepage through soil

into groundwaterSlide9

Animation: The Hydrologic CycleSlide10

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The carbon cycle has major reservoirs in the atmosphere and oceans

Carbon atoms form the framework of all organic molecules

The

carbon cycle

is the pathway that carbon takes from its major short-term reservoirs in the atmosphere and oceans, through producers and into the bodies of consumers, detritivores, and decomposers, and then back again to its reservoirsSlide11

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The carbon cycle has major reservoirs in the atmosphere and oceans

(continued)

Carbon enters communities through capture of carbon dioxide (CO

2

) during photosynthesis

Producers on land get CO

2

from the atmosphere

Aquatic producers get CO

2

dissolved in the water Slide12

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The carbon cycle has major reservoirs in the atmosphere and oceans

(continued)

Primary consumers eat producers and acquire carbon stored in their tissues

These herbivores release some of the carbon through respiration as CO

2

, excrete carbon compounds in their feces, and store the rest in their bodies, which may be consumed by higher trophic levels Slide13

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The carbon cycle has major reservoirs in the atmosphere and oceans

(continued)

All living things eventually die, and their bodies are broken down by detritivores and decomposers, whose cellular respiration returns CO

2

to the atmosphere and oceans

The complementary processes of uptake by photosynthesis and release by cellular respiration continually recycle carbon from the abiotic to the biotic portions of an ecosystem and back againSlide14

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The carbon cycle has major reservoirs in the atmosphere and oceans

(continued)

Much of Earth’s carbon is bound up in limestone rock, formed from calcium carbonate (CaCO

3

) deposited on the ocean floor in the shells of prehistoric phytoplankton

Fossil fuels

, which include coal, oil, and natural gas, are additional long-term reservoirs for carbonSlide15

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The carbon cycle has major reservoirs in the atmosphere and oceans

(continued)

These substances were produced from the remains of prehistoric organisms buried deep underground and subjected to high temperature and pressure

In addition to carbon, the energy of prehistoric sunlight is trapped in these deposits

When human beings burn fossil fuels to tap this stored energy, CO

2

is released into the atmosphere, with potentially serious consequencesSlide16

Animation: The Carbon CycleSlide17

Figure 28-7

The carbon cycle

reservoirs

processes

trophic levels

CO

2

dissolved

in the ocean

CO

2

in the

atmosphere

burning

fossil fuels

respiration

fire

consumers

producers

photosynthesis

fossil fuels

(coal, oil, natural gas)

detritivores

and decomposers

decompositionSlide18

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The nitrogen cycle has its major reservoir in the atmosphere

Nitrogen is a crucial component of proteins, many vitamins, nucleotides (such as ATP), and nucleic acids (such as DNA)

The

nitrogen cycle

is the pathway taken by nitrogen from its primary reservoir—nitrogen gas (N

2

) in the atmosphere—to much smaller reservoirs of ammonia and nitrate in soil and water, through producers, consumers, detritivores and decomposers, and back to its reservoirsSlide19

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The nitrogen cycle has its major reservoir in the atmosphere

(continued)

While nitrogen gas (N

2

) makes up 78% of the atmosphere, this form of nitrogen cannot be utilized by plants

Plants utilize nitrate (NO

3



) or ammonia (NH

3

) as their nitrogen source Slide20

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The nitrogen cycle has its major reservoir in the atmosphere

(continued)

N

2

is converted to ammonia by specific bacteria during a process called

nitrogen fixation

Some of these bacteria live in water and soil and convert the ammonia into nitrate that plants can directly use

Others live in symbiotic associations with plants called

legumes

, which include alfalfa, soybeans, clover, and peas Slide21

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The nitrogen cycle has its major reservoir in the atmosphere

(continued)

Some nitrogen is released in wastes and dead bodies

Decomposer bacteria convert this back to nitrate and ammonia in the soil or water, which is then available to plants

Denitrifying bacteria

break down nitrate, releasing N

2

back to the atmosphere Slide22

28.3 How Do Nutrients Cycle Within and Among Ecosystems?

The nitrogen cycle has its major reservoir in the atmosphere

(continued)

People significantly manipulate the nitrogen cycle, both deliberately and unintentionally

About 150 million tons of nitrogen-based fertilizer are applied to farms each year

The heat produced by burning fossil fuels combines atmospheric N

2

and O

2

, generating nitrogen oxides that form nitrates

Human activities now dominate the nitrogen cycle Slide23

Animation: The Nitrogen CycleSlide24

Figure 28-8

The nitrogen cycle

reservoirs

processes

trophic levels

burning

fossil fuels

N

2

in the

atmosphere

lightning

application of

manufactured fertilizer

producers

consumers

decomposition

ammonia and

nitrates in water

denitrifying

bacteria

detritivores

and decomposers

uptake by

producers

ammonia

and nitrates

in soil

nitrogen-fixing

bacteria in soil

and legume rootsSlide25

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Ancient peoples, with small populations and limited technology, had relatively little impact on nutrient cycles

As the human population grew and technology increased, people began to act more independently of natural ecosystem processes

The Industrial Revolution resulted in a tremendous increase in our reliance on energy stored in fossil fuels for heat, light, transportation, industry, and agricultureSlide26

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Fertilizer use on commercial farms grew exponentially

Human use of fossil fuels and chemical fertilizers has significantly disrupted the global nutrient cycles of nitrogen, phosphorus, sulfur, and carbonSlide27

Figure 28-10

An algal bloom in the Gulf of MexicoSlide28

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the nitrogen and phosphorus cycles damages aquatic ecosystems

Fertilizers are applied to farm fields to help satisfy the agricultural demands of a growing human population

Water dissolves and carries away some of the phosphate and nitrogen-based fertilizer

As water drains into lakes, rivers, and ultimately the oceans, these fertilizers can disrupt the delicate balance of food webs by overstimulating the growth of phytoplankton Slide29

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the nitrogen and phosphorus cycles damages aquatic ecosystems

(continued)

The phytoplankton die, and their bodies sink into deeper water and provide food for decomposer bacteria

The decomposers use up most of the available oxygen, and other aquatic organisms, such as invertebrates and fish, die, creating “dead zones” in many waters Slide30

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the sulfur and nitrogen cycles causes acid deposition

Burning of sulfur-containing fossil fuels, primarily coal, accounts for about 75% of all sulfur dioxide emissions worldwide

These two substances combine with atmospheric water and form nitric and sulfuric acids

Days later and often hundreds of miles from the source, these acids fall to Earth in rain or snow Slide31

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the sulfur and nitrogen cycles causes acid deposition

(continued)

This “acid rain”—more accurately called

acid deposition

—was first recognized in New Hampshire, where a sample of rain collected in 1963 had a pH of 3.7, about the same as that of orange juice

Acid deposition damages forests, can render lakes lifeless, and even eats away at buildings and statuesSlide32

Figure 28-11

Acid deposition is corrosiveSlide33

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the sulfur and nitrogen cycles causes acid deposition

(continued)

Many lakes and ponds in the Adirondack Mountains are too acidic to support fish

Acid rain also increases the extent to which organisms are exposed to toxic metals, such as aluminum, mercury, lead, and cadmium, which are far more soluble in acidified water Slide34

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the sulfur and nitrogen cycles causes acid deposition

(continued)

Acid conditions dissolve aluminum out of the soil into soil water and lakes, where it inhibits plant growth and kills fish

Calcium and magnesium, which are essential nutrients for all plants, are leached out of the soil by acid precipitationSlide35

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the sulfur and nitrogen cycles causes acid deposition

(continued)

Plants in acidified soil become weak and more vulnerable to infection and damage by insects

The decline has been shown to be caused by acid conditions, coupled with drought, insect attack, and climate change

About half of the red spruce and one-third of the sugar maples in the Green Mountains of Vermont have been killedSlide36

Figure 28-12

Acid deposition can destroy forestsSlide37

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the sulfur and nitrogen cycles causes acid deposition

(continued)

Since 1990, government regulations have resulted in substantial reductions in emissions of both sulfur dioxide and nitrogen oxides from U.S. power plants

Sulfur dioxide emissions are down about 40% and nitrogen oxide levels have been reduced by more than 50%

Air quality has improved, and rain has become less acidicSlide38

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Overloading the sulfur and nitrogen cycles causes acid deposition

(continued)

Damaged ecosystems recover slowly

Adirondack lakes are gradually becoming less acidic

If acid deposition is completely eliminated, eventually the lakes will return to their normal pH

Most aquatic life should then recover in 3 to 10 years, depending on the species

Forests will take much longer to recoverSlide39

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Interfering with the carbon cycle is warming Earth’s climate

Some of the energy from sunlight is reflected back into space by the atmosphere, and by Earth’s surface, especially by areas covered with snow or ice

Most sunlight strikes relatively dark areas of the surface and is converted into heat that is radiated into the atmosphere

Water vapor, CO

2

, and several

greenhouse gases

trap some of the heat in the atmosphereSlide40

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Interfering with the carbon cycle is warming Earth’s climate

(continued)

This is a natural process called the

greenhouse effect

, which keeps our atmosphere relatively warm and allows life on Earth as we know it

For Earth’s temperature to remain constant, the total amount of energy entering and leaving Earth’s atmosphere must be equalSlide41

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Interfering with the carbon cycle is warming Earth’s climate

(continued)

If atmospheric concentrations of greenhouse gases increase, more heat is retained than is radiated into space, causing Earth to warm

Greenhouse gases are increasing because people burn fossil fuels, releasing CO

2

Other important greenhouse gases include methane (CH

4

), released by agricultural activities and burning fossil fuelsSlide42

Figure 28-13

The greenhouse effect

volcanoes

forest

fires

power plants

and factories

homes and other

buildings

agricultural

activities

Heat is

radiated back into

the atmosphere

Some atmospheric heat is

retained by greenhouse gases

Most heat is radiated

into space

Sunlight energy

enters the atmosphere

Some energy

is reflected back

into space

Most sunlight strikes

Earth’s surface and is

converted into heat

vehicle

emissions

SunSlide43

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Burning fossil fuels is causing climate change

Since the mid-1800s, human societies have increasingly relied on energy from fossil fuels

As we burn fossil fuel in our power plants, factories, and cars, we harvest the energy of ancient sunlight and release CO

2

into the atmosphere

Burning fossil fuels accounts for about 80% to 85% of the CO

2

human activities release into the atmosphere annuallySlide44

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Burning fossil fuels is causing climate change

(continued)

A second source of added atmospheric CO

2

is

deforestation

, which destroys tens of millions of forested acres annually and accounts for 15% of CO

2

emissions

Deforestation occurs principally in the tropics as rain forests are cut and burned

Collectively, human activities release about 35 to 40 billion tons of CO

2

into the atmosphere annuallySlide45

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Burning fossil fuels is causing climate change

(continued)

Since 1850, atmospheric CO

2

has increased by 40%

This increase is from 280 ppm to 392 ppm, with a current annual increase of 2 ppm

A larger and growing body of evidence indicates that human release of carbon dioxide and other greenhouse gases has amplified the natural greenhouse effect, thereby altering the global climateSlide46

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Burning fossil fuels is causing climate change

(continued)

Surface temperature data, recorded from thousands of weather stations around the world and from satellites that measure temperatures over oceans, show that Earth has warmed by about 1



F (0.6



C) since 1970

The overall impact of increased greenhouse gases is now usually called

climate change

, which includes both global warming and many other effects on our climate and Earth’s ecosystemsSlide47

Figure 28-14

Global temperature increases parallel atmospheric CO

2

increases

390

380

370

360

350

340

330

320

310

CO

2

(ppm)

300

1960

1970

1980

1990

2000

2010

year

Atmospheric CO

2

Global surface temperature

1960

1970

1980

1990

2000

2010

year

58.1

57.9

57.7

57.6

14.2

14.3

14.4

14.5

14.1

14.0

13.9

13.8

57.4

57.2

57.0

56.8

global average temperature



F



CSlide48

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Burning fossil fuels is causing climate change

(continued)

Spring snow in the Northern Hemisphere is declining

Glaciers are retreating worldwide

The World Glacier Monitoring Service reports that about 90% of the world’s mountain glaciers are shrinking, and that this trend seems to be accelerating

Glacier National Park, Montana, now has only 25 glaciers remainingSlide49

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Burning fossil fuels is causing climate change

(continued)

Climate scientists predict that the warming atmosphere will cause more severe storms, including stronger hurricanes

Greater amounts of rain or snow will fall in single storms

More frequent and more prolonged droughts will occur

Increased CO

2

makes the oceans more acidicSlide50

Figure 28-15

Glaciers are melting

Muir Glacier, 1941

Muir Glacier, 2004Slide51

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Continued climate change will disrupt ecosystems and endanger many species

Predictions of continued climate change are based on sophisticated computer models developed and run independently by climate scientists around the world

As models improve, they match past climate with ever-greater accuracy, providing increasing confidence in their predictions for the futureSlide52

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Continued climate change will disrupt ecosystems and endanger many species

(continued)

The models provide evidence that natural causes cannot account for the recent warming

The models match the data only when human carbon emissions are included in the calculations

The Intergovernmental Panel on Climate Change (IPCC) predicted that even under the best-case scenario, the average global temperature will rise by at least 3.2



F (1.8



C) by the year 2100Slide53

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Continued climate change will disrupt ecosystems and endanger many species

(continued)

The IPCC’s high-level emissions scenario projects an increase of 7.2



F (4.0



C)

Thousands of species will change their ranges, moving away from the equator toward the poles or higher up mountainsides

Some plants and animals will find it easier to move than othersSlide54

Figure 28-16

Projected range of temperature increases

7.2

4.0

3.0

5.4

3.6

2.0

1.0

1.8



F



C

0.0

0.0

projected global temperature increase

2000

2020

2040

2060

2080

2100

yearSlide55

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Continued climate change will disrupt ecosystems and endanger many species

(continued)

It is highly unlikely that entire communities of organisms can just pack and move, intact

Some species will have nowhere to go

For example, the loss of summer sea ice is bad news for polar bears and other marine mammals that rely on ice floes as nurseries for their youngSlide56

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Continued climate change will disrupt ecosystems and endanger many species

(continued)

Some of the movement of species may have direct impact on human health

Many diseases, especially those carried by mosquitoes and ticks, are currently restricted to tropical or subtropical parts of the planet

These disease vectors will probably spread poleward as a result of warming temperatures, bringing their diseases, such as malariaSlide57

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Continued climate change will disrupt ecosystems and endanger many species

(continued)

Some of the movement of species may have direct impact on human health

(continued)

It may become so hot and dry in parts of the tropics that mosquitoes and some other insects may have shortened life spans, thus reducing vector-borne diseases in these regionsSlide58

28.4 What Happens When Humans Disrupt Nutrient Cycles?

Continued climate change will disrupt ecosystems and endanger many species

(continued)

Although computer models can predict temperature changes, no one can confidently predict the resulting overall effects on human health