(8)chapter 54

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures for Biology, Seventh Edition

Neil Campbell and Jane Reece

Lectures by Chris Romero

(8) Chapter 54(8) Chapter 54

Ecosystems ( 生態系統 )

Ecology ( 生態學 )


Key Concepts• Concept 54.1: Ecosystem ecology emphasizes energy

flow and chemical cycling ( 生態系統強調能量流通與化學循環 )

• Concept 54.2: Physical and chemical factors limit primary production in ecosystems ( 物理與化學因子限制生態系統的初級生產量 )

• Concept 54.3: Energy transfer between trophic levels is usually less than 20% efficient ( 不同食性階層的能量轉移效率低於 20%)

• Concept 54.4: Biological and geochemical processes move nutrients between organic and inorganic parts of the ecosystem ( 生物與地質化學過程生態系統有機與無機間的營養 )

• Concept 54.5: The human population is disrupting chemical cycles throughout the biosphere ( 人類族群破壞生物圈的化學循環 )


• Overview: Ecosystems, Energy, and Matter

• An ecosystem consists of all the organisms living in a community as well as all the abiotic factors ( 非生物因子 ) with which they interact

• Ecosystems can range from a microcosm ( 微宇宙 ), such as an aquarium ( 水族館 ) to a large area such as a lake or forest

• An aquarium is an

ecosystem bounded

by glass

Figure 54.1


• Regardless of an ecosystem’s size ( 不論生態系統的尺度大小 )

– Its dynamics involve two main processes: energy flow and chemical cycling ( 能量流通與化學循環 )

• Energy flows through ecosystems

– While matter cycles ( 物質循環 ) within them


• Concept 54.1: Ecosystem ecology emphasizes energy flow and chemical cycling ( 生態系生態學強調能量流通與化學循環 )

• Ecosystem ecologists view ecosystems as

– Transformers of energy ( 能量的轉換機器 )

– processors of matter ( 物質的加工機器 )


Ecosystems and Physical Laws ( 物理定律 )

• The laws of physics and chemistry apply to ecosystems ( 物理與化學定律適用於生態系統 )

– Particularly in regard to the flow of energy. Two laws of thermodynamics govern energy transformations in organism and all other collections of matter

– The first law of thermodynamics: energy can be transferred and transformed, but it cannot be created or destroyed (The principle of conservation of energy，能量守恆 )

– The second law of thermodynamics: every energy transfer or transformation increases the disorder (entropy) of the universe. Energy conversions cannot be completely efficient; some energy is always lost as heat in any conversion process

• Energy is conserved, but degraded to heat during ecosystem processes ( 能量不滅，但是在生態系統變遷過程能量轉化為熱量 )


Trophic Relationships ( 不同營養階層的關係 )

• Nutrients cycle within an ecosystem

• Decomposition ( 分解作用 )

– Connects all trophic levels ( 聯繫所有營養階層 )

• Energy and nutrients pass from primary producers (autotrophs) 初級生產者 ( 自營生物 )

– To primary consumers (herbivores 食草動物 / 草食者 ) and then to secondary consumers (carnivores食肉動物 / 肉食者 )


生態系統中的能量流通與化學循環• Energy flows through an ecosystem entering

as light and exiting as heat

Figure 54.2

Microorganismsand other

detritivores

Detritus碎屑

Primary producers

Primary consumers

Secondaryconsumers

Tertiary consumers

HeatSun light

Key

Chemical cyclingEnergy flow

三級消費者

次級消費者

初級消費者

初級生產者

微生物及其它碎食者


• Detritivores ( 碎食生物 / 碎食者 ), mainly bacteria and fungi, recycle essential chemical elements

– By decomposing organic material and transferring the chemical elements in inorganic forms to abiotic reservoirs, i.e. returning elements to inorganic reservoirs

Figure 54.3


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• Concept 54.2: Physical and chemical factors limit primary production in ecosystems

• Primary production ( 初級生產力 ) in an ecosystem

– Is the amount of light energy converted to chemical energy by autotrophs during a given time period

• Ecosystem Energy Budgets ( 生態系的能量預算 )

– The extent of photosynthetic production sets the spending limit for the energy budget of the entire ecosystem


The Global Energy Budget ( 全球的能量預算 )

• The amount of solar radiation reaching the surface of the Earth

– Limits the photosynthetic output of ecosystems

• Only a small fraction of solar energy

– Actually strikes photosynthetic organisms


Gross and Net Primary Production (GPP &NPP)

• Total primary production in an ecosystem

– Is known as that ecosystem’s gross primary production (GPP)( 總體初級生產力是所有初級生產力的總和 )

• Not all of this production

– Is stored as organic material in the growing plants

• Net primary production (NPP)( 淨初級生產力 )

– Is equal to GPP minus the energy used by the primary producers for respiration (R) NPP=GPP-R

• Only NPP

– Is available to consumers


• Different ecosystems vary considerably in their net primary production and in their contribution to the total NPP on Earth

Lake and stream

Open oceanContinental shelf

EstuaryAlgal beds and reefs

Upwelling zonesExtreme desert, rock, sand, iceDesert and semidesert scrub

Tropical rain forestSavanna

Cultivated landBoreal forest (taiga)

Temperate grassland

TundraTropical seasonal forest

Temperate deciduous forestTemperate evergreen forest

Swamp and marsh

Woodland and shrubland

0 10 20 30 40 50 60 0 500 1,000 1,500 2,000 2,500 0 5 10 15 20 25Percentage of Earth’s netprimary production

Key

Marine

Freshwater (on continents)

Terrestrial

5.20.30.10.1

4.73.53.32.92.72.41.81.71.61.51.31.00.40.4

125360

1,5002,500

5003.090

2,200900

600800

600700

1401,600

1,2001,300

2,000250

5.61.20.9

0.10.040.9

227.9

9.19.6

5.43.5

0.67.1

4.93.8

2.30.3

65.0 24.4

Figure 54.4a–c

Percentage of Earth’ssurface area

(a) Average net primaryproduction (g/m2/yr)(b) (c)


• Overall, terrestrial ecosystems ( 陸域生態系統 ) contribute about two-thirds (2/3) of global NPP and marine ecosystems about one-third (1/3)

Figure 54.5. Regional annual net primary production for earth. The image is based on data, such as chlorophyll density by satellite. (Low) lighter violet→blue→green→yellow→orange→dark red (High)

180 120W 60W 0 60E 120E 180

North Pole

60N

30N

Equator

30S

60S

South Pole


Primary Production in Marine and Freshwater Ecosystems ( 海洋與淡水生態系的初級生產力 )• In marine and freshwater ecosystems

– Both light and nutrients are important in controlling primary production

• Light Limitation ( 光線限制 )

– The depth of light penetration affects primary production throughout the photic zone of an ocean or lake

• Nutrient Limitation ( 養份限制 )

– More than light, nutrients limit primary production, both in different geographic regions of the ocean and in lakes


• A limiting nutrient ( 限制性養份 ) is the element that must be added

– In order for production to increase in a particular area

• Nitrogen (N) and phosphorous ( P)

– Are typically the nutrients that most often limit marine production


• Nutrient enrichment experiments confirmed that nitrogen (N) was limiting phytoplankton growth in an area of the ocean

Experiment: Pollution from duck farms concentrated near Moriches Bay adds both nitrogen (N) and phosphorus (P) to the coastal water off Long Island. Researchers cultured the phytoplankton Nannochloris atomus with water collected from several bays.

Figure 54.6

Coast of Long Island, New York. The numbers on the map indicate the data collection stations.

Long Island

Great South Bay

Shinnecock Bay

Moriches Bay

Atlantic Ocean

30 21

1915

1154

2


Figure 54.6

Conclusion: Since adding phosphorus, which was already in rich supply, had no effect on Nannochloris growth, whereas adding nitrogen increased algal density dramatically, researchers concluded that nitrogen was the nutrient limiting phytoplankton growth in this ecosystem.

(a) Phytoplankton biomass and phosphorus concentration (b) Phytoplankton response to nutrient enrichment

GreatSouth Bay

MorichesBay

ShinnecockBay

Startingalgal

density

2 4 5 11 30 15 19 21

30

24

18

12

6

0

Unenriched control

Ammonium enrichedPhosphate enriched

Station numberP

hy

top

lan

kto

n(m

illi

on

s o

f c

ell

s p

er

mL

)

87

6

5

4

3

2

1

02 4 5 11 3015 19 21

87

6

54

32

1

0

Ino

rga

nic

ph

os

ph

oru

s(

g a

tom

s/L

)

Ph

yto

pla

nk

ton

(mil

lio

ns

of

ce

lls

/mL

)

Station number

Phytoplankton

Inorganicphosphorus

Results: Phytoplankton abundance parallels the abundance of phosphorus in the water (a). Nitrogen, however, is immediately taken up by algae, and no free nitrogen is measured in the coastal waters. The addition of ammonium (NH4

) caused heavy phytoplankton growth in bay water, but the addition of phosphate (PO4

3) did not induce algal growth (b).


• Experiments in another ocean region showed that iron (Fe) limited primary production

Table 54.1


• The addition of large amounts of nutrients to lakes

– Has a wide range of ecological impacts ( 生態衝擊 )

• In some areas, sewage runoff

– Has caused eutrophication of lakes ( 湖泊優養化 ), which can lead to the eventual loss of most fish species from the lakes

Figure 54.7


Primary Production in Terrestrial and Wetland Ecosystems( 陸域及溼地生態系的初級生產力 )

• In terrestrial and wetland ecosystems climatic factors

– Such as temperature and moisture, affect primary production on a large geographic scale( 大的地理尺度 )

• The contrast between wet and dry climates

– Can be represented by a measure called actual evapotranspiration


• Actual evapotranspiration ( 蒸發散作用 )

– Is the amount of water annually transpired by plants and evaporated from a landscape

– Is related to net primary production

Figure 54.8Actual evapotranspiration (mm H2O/yr)

Tropical forest (熱帶雨林 )

Temperate forest (溫帶雨林 )Mountain coniferous forest (高山針葉林 )

Temperate grassland (溫帶草原 )

Arctic tundra (極地苔原 )

Desertshrubland

Net

pri

mar

y p

rod

uct

ion

(g

/m2 /

yr)

1,000

2,000

3,000

0500 1,000 1,5000


• On a more local scale ( 地區性尺度 )

– A soil nutrient is often the limiting factor in primary production ( 土壤營養通常是初級生產力的限制因子 )

Figure 54.9

EXPERIMENTOver the summer of 1980, researchers added phosphorus (P) to some experimental plots in the salt marsh, nitrogen (N) to other plots, and both phosphorus (P) and nitrogen (N) to others. Some plots were left unfertilized as controls.

RESULTS

Experimental plots receiving just phosphorus (P) do not outproduce the unfertilized control plots.

CONCLUSION

Liv

e,

ab

ov

e-g

rou

nd

bio

ma

ss

(g d

ry w

t/m

2 )

Adding nitrogen (N) boosts net primaryproduction.

300

250

200

150

100

50

0

June July August 1980

N P

N only

Control

P only

These nutrient enrichment experiments confirmed that nitrogen was the nutrient limiting plant growth in this salt marsh.



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• Concept 54.3: Energy transfer between trophic levels is usually less than 20% efficient

• The secondary production of an ecosystem

– Is the amount of chemical energy in consumers’ food that is converted to their own new biomass during a given period of time


Production Efficiency

• When a caterpillar feeds on a plant leaf

– Only about one-sixth (1/6) of the energy in the leaf is used for secondary production ( 次級生產 )

Figure 54.10

Plant materialeaten by caterpillar

Cellularrespiration

Growth (new biomass)

Feces 100 J33 J

200 J

67 J


• The production efficiency of an organism

– Is the fraction of energy stored in food that is not used for respiration


Trophic Efficiency and Ecological Pyramids

• Trophic efficiency ( 營養層級效應 )

– Is the percentage of production transferred from one trophic level to the next

– Usually ranges from 5% to 20%


Pyramids of Net Production ( 淨生產力金字塔 )

• This loss of energy with each transfer in a food chain can be represented by a pyramid of net production

Figure 54.11

Tertiaryconsumers

Secondaryconsumers

Primaryconsumers

Primaryproducers

1,000,000 J of sunlight

10 J

100 J

1,000 J

10,000 J

三級消費者

次級消費者

初級消費者

初級生產者


Pyramids of Biomass ( 生物量金字塔 )

• One important ecological consequence of low trophic efficiencies ( 低營養階層效率 )

– Can be represented in a biomass pyramid


Biomass pyramids ( 生物能量塔 )

• Most biomass pyramids show a sharp decrease at successively higher trophic levels ( 高營養階層 )

Figure 54.12a

Trophic level Dry weight (g/m2)

Primary producers

Tertiary consumers

Secondary consumersPrimary consumers

1.5

1137809

(a) Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida.

三級消費者次級消費者初級消費者初級生產者

營養階層


• Certain aquatic ecosystems ( 水域生態系 ) have inverted biomass pyramids

Figire 54.12b

Trophic level

Primary producers (phytoplankton 浮游植物 )

Primary consumers (zooplankton 浮游動物 )

Dry weight (g/m2)

21

4

(b) In some aquatic ecosystems, such as the English Channel, a small standing crop of primary producers (phytoplankton) supports a larger standing crop of primary consumers (zooplankton).


Pyramids of Numbers ( 數量金字塔 )

• A pyramid of numbers represents the number of individual organisms in each trophic level ( 數量金字塔代表各營養層級的個體數目 )

Figure 54.13

Trophic level Number of individual organisms

Primary producers

Tertiary consumers

Secondary consumers

Primary consumers

3

354,904

708,624

5,842,424


• The dynamics of energy flow through ecosystems have important implications for the human population

• Eating meat is a relatively inefficient way of tapping photosynthetic production

• Worldwide agriculture could successfully feed many more people if humans all fed more efficiently, eating only plant material

Figure 54.14

Trophic level

Secondaryconsumers

Primaryconsumers

Primaryproducers


The Green World Hypothesis ( 綠色世界假說 )

• According to the green world hypothesis

– Terrestrial herbivores consume relatively little plant biomass because they are held in check by a variety of factors

• Most terrestrial ecosystems( 陸域生態系 )

– Have large standing crops despite the large numbers of herbivores( 草食動物 )

Figure 54.15


綠色世界假說• The green world hypothesis proposes several

factors that keep herbivores in check

– Plants have defenses against herbivores

– Nutrients, not energy supply, usually limit herbivores

– Abiotic factors ( 非生物因子 ) limit herbivores

– Intraspecific competition ( 種內競爭 ) can limit herbivore numbers

– Interspecific interactions ( 種間互動 ) check herbivore densities



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• Concept 54.4: Biological and geochemical processes move nutrients between organic and inorganic parts of the ecosystem

• Life on Earth

– Depends on the recycling of essential chemical elements

• Nutrient circuits that cycle matter through an ecosystem

– Involve both biotic and abiotic components and are often called biogeochemical cycles ( 生物地質化學循環 )


A General Model of Chemical Cycling( 化學循環 )

• Gaseous forms of carbon (C), oxygen (O), sulfur (S), and nitrogen (N)

– Occur in the atmosphere and cycle globally ( 全球性循環 )

• Less mobile elements, including phosphorous (P), potassium (K), and calcium (Ca)

– Cycle on a more local level ( 地區性或區域性循環 )


Nutrient cycling ( 營養循環 )

• A general model of nutrient cycling ( 營養循環 )

– Includes the main reservoirs of elements and the processes that transfer elements between reservoirs

– All elements cycle between organic and inorganic reservoirs

Figure 54.16

Organicmaterialsavailable

as nutrientsLivingorganisms,detritus

Organicmaterials

unavailableas nutrients

Coal, oil,peat

Inorganicmaterialsavailable

as nutrients

Inorganicmaterials

unavailableas nutrients

Atmosphere,soil, water

Mineralsin rocksFormation of

sedimentary rock

Weathering,erosion

Respiration,decomposition,excretion

Burningof fossil fuels

Fossilization

Reservoir a Reservoir b

Reservoir c Reservoir d

Assimilation, photosynthesis


Biogeochemical Cycles ( 生物地質化學循環 )

• The water cycle and the carbon cycle ( 水循環及碳循環 )

Transportover land

Solar energy

Net movement ofwater vapor by wind

Precipitationover ocean

Evaporationfrom ocean

Evapotranspirationfrom land

Precipitationover land

PercolationthroughsoilRunoff and

groundwater

CO2 in atmosphere

Photosynthesis

Cellularrespiration

Burning offossil fuelsand wood Higher-level

consumersPrimaryconsumers

DetritusCarbon compounds in water

Decomposition

THE WATER CYCLE THE CARBON CYCLE

Figure 54.17


• Water moves in a global cycle ( 全球循環 )

– Driven by solar energy ( 太陽能 )

• The carbon cycle ( 碳循環 )

– Reflects the reciprocal processes of photosynthesis and cellular respiration

( 反應光合作用與呼吸作用的相反過程 )


Nitrogen cycle (N) and the phosphorous cycle (P)

• The nitrogen cycle and the phosphorous cycle ( 氮循環及磷循環 )

N2 in atmosphere

Denitrifyingbacteria

Nitrifyingbacteria

Nitrifyingbacteria

Nitrification

Nitrogen-fixingsoil bacteria

Nitrogen-fixingbacteria in rootnodules of legumes

Decomposers

Ammonification

Assimilation

NH3 NH4+

NO3

NO2

Rain

Plants

Consumption

Decomposition

Geologicuplift

Weatheringof rocks

Runoff

Sedimentation Plant uptakeof PO4

3Soil

Leaching滲漏作用

THE NITROGEN CYCLE THE PHOSPHORUS CYCLE

Figure 54.17


• Most of the nitrogen cycling in natural ecosystems

– Involves local cycles between organisms and soil or water

• The phosphorus cycle

– Is relatively localized

• The rates at which nutrients cycle in different ecosystems

– Are extremely variable, mostly as a result of differences in rates of decomposition


Decomposition and Nutrient Cycling Rates

• Decomposers (detritivores, 分解者 ) play a key role

– In the general pattern of chemical cycling

Figure 54.18

Consumers

Producers

Nutrientsavailable

to producers

Abioticreservoir

Geologicprocesses

DecomposersBiotic (生物性 )

Abiotic (非生物性 )


Vegetation and Nutrient Cycling: The Hubbard Brook Experimental Forest

• Nutrient cycling is strongly regulated by vegetation( 植被強烈地調節營養循環 )

• Long-term ecological research (LTER) projects ( 長期生態研究 )

– Monitor ecosystem dynamics over relatively long periods of time

• The Hubbard Brook Experimental Forest

– Has been used to study nutrient cycling in a forest ecosystem since 1963


• The research team constructed a dam on the site

– To monitor water and mineral loss

Figure 54.19a

(a) Concrete dams and weirs built across streams at the bottom of watersheds enabled researchers to monitor the outflow of water and nutrients from the ecosystem.


• In one experiment, the trees in one valley were cut down and the valley was sprayed with herbicides ( 除草劑 )

Figure 54.19b(b) One watershed was clear cut to study the effects of the loss

of vegetation on drainage and nutrient cycling.


• Net losses of water and minerals were studied and found to be greater than in an undisturbed area

• These results showed how human activity can affect ecosystems

Figure 54.19c(c) The concentration of nitrate in runoff from the

deforested watershed was 60 times greater than in a control (unlogged) watershed.

Nit

rate

co

nce

ntr

atio

n i

n r

un

off

(mg

/L)

Deforested

Control

Completion oftree cutting

1965 1966 1967 1968

80.0

60.0

40.0

20.0

4.0

3.02.0

1.00



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• Concept 54.5: The human population is disrupting chemical cycles throughout the biosphere

• As the human population has grown in size

– Our activities have disrupted the trophic structure, energy flow, and chemical cycling of ecosystems in most parts of the world

• Nutrient Enrichment

– In addition to transporting nutrients from one location to another, humans have added entirely new materials, some of them toxins, to ecosystems


Agriculture and Nitrogen Cycling ( 農業與氮循環 )

• Agriculture constantly removes nutrients from ecosystems that would ordinarily be cycled back into the soil.

• Nitrogen (N) is the main nutrient lost through agriculture. Thus, agriculture has a great impact on the nitrogen cycle.

• Industrially produced fertilizer is typically used to replace lost nitrogen (N), but the effects on an ecosystem can be harmful.

Figure 54.20


Contamination of Aquatic Ecosystems ( 水域生態系的污染 )

• The critical load for a nutrient

– Is the amount of that nutrient that can be absorbed by plants in an ecosystem without damaging it

• When excess nutrients are added to an ecosystem, the critical load is exceeded

– And the remaining nutrients can contaminate groundwater and freshwater and marine ecosystems

• Sewage runoff contaminates freshwater ecosystems

– Causing cultural eutrophication ( 栽培的優養化 ), excessive algal growth ( 藻類過度生長 ), which can cause significant harm to these ecosystems


Figure 54.21

4.6

4.64.3

4.14.34.6

4.64.3

Europe

North America

Acid Precipitation 酸雨 (1)

• Combustion of fossil fuels

– Is the main cause of acid precipitation

• North American and European ecosystems downwind from industrial regions

– Have been damaged by rain and snow containing nitric and sulfuric acid ( 硝酸及硫酸 )



• By the year 2000

– The entire contiguous United States was affected by acid precipitation

Figure 54.22

Field pH5.35.2–5.35.1–5.25.0–5.14.9–5.04.8–4.94.7–4.84.6–4.74.5–4.64.4–4.54.3–4.44.3



• Environmental regulations and new industrial technologies

– Have allowed many developed countries to reduce sulfur dioxide (SO2) emissions in the past 30 years


Toxins in the Environment

• Humans release an immense variety of toxic chemicals

– Including thousands of synthetics previously unknown to nature

• One of the reasons such toxins are so harmful

– Is that they become more concentrated in successive trophic levels of a food web

• In some cases, harmful substances ( 有害物質 )

– Persist for long periods of time in an ecosystem and continue to cause harm


Biological magnification ( 生物放大效應 )

• In biological magnification

– Toxins concentrate at higher trophic levels because at these levels biomass tends to be lower

Figure 54.23

Co

nce

ntr

atio

n o

f P

CB

s Herringgull eggs124 ppm

Zooplankton 0.123 ppm

Phytoplankton 0.025 ppm

Lake trout 4.83 ppm

Smelt 1.04 ppm


Rising Atmospheric CO2

• One pressing problem caused by human activities is the rising level of atmospheric carbon dioxide

• Due to the increased burning of fossil fuels and other human activities, the concentration of atmospheric CO2 has been

steadily increasing

Figure 54.24

CO

2 co

nce

ntr

atio

n (

pp

m)

390

380

370

360

350

340

330

320

310

3001960 1965 19701975 1980 1985 1990 19952000 2005

1.05

0.90

0.75

0.60

0.45

0.30

0.15

0

0.15

0.30

0.45 Tem

per

atu

re v

aria

tio

n (C

)

Temperature

CO2

Year


How Elevated CO2 Affects Forest Ecology: The FACTS-I Experiment

• The FACTS-I experiment is testing how elevated CO2

– Influences tree growth, carbon concentration in soils, and other factors over a ten-year period

Figure 54.25


The Greenhouse Effect and Global Warming

• CO2 magnifies the greenhouse effect

– Increased levels of atmospheric CO2 are magnifying the greenhouse effect, which could cause global warming and significant climatic change

• The greenhouse effect is caused by atmospheric CO2

– But is necessary to keep the surface of the Earth at a habitable temperature


Depletion of Atmospheric Ozone (O3)

• Life on Earth is protected from the damaging effects of UV radiation, by a protective layer or ozone molecules present in the atmosphere

Figure 54.26

Ozo

ne

laye

r th

ickn

ess

(Do

bso

n u

nit

s)

Year (Average for the month of October)

350

300

250

200

150

100

50

019551960 19651970197519801985 1990199520002005

•Satellite studies of the atmosphere suggest that the ozone layer has been gradually thinning since 1975


• The destruction of atmospheric ozone ( 大氣臭氧的破壞 )

– Probably results from chlorine-releasing pollutants produced by human activity

Figure 54.27

1

2

3

Chlorine from CFCs interacts with ozone (O3),forming chlorine monoxide (ClO) and oxygen (O2).

Two ClO molecules react, forming chlorine peroxide (Cl2O2).

Sunlight causes Cl2O2 to break down into O2 and free chlorine atoms. The chlorine atoms can begin the cycle again. Sunlight

Chlorine O3

O2

ClO

ClO

Cl2O2

O2

Chlorine atoms


Ozone hole ( 臭氧洞 )

• Scientists first described an “ozone hole”

– Over Antarctica in 1985; it has increased in size as ozone depletion has increased

Figure 54.28a, b

(a) October 1979 (b) October 2000



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(8)chapter 54

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