KARAKTERISTIK KETAHANAN EKO- SISTEM

KARAKTERISTIK

KETAHANAN EKO-

SISTEM

Mk. Analisis Ekosistem

Diabstraksikan: smno.psdl.pdkl.ppsub.2012/13

1. Biodiversity = the amount of biological or living diversity per unit area. It includes the concepts of species diversity, genetic diversity and habitat diversity

2. Genetic diversity = the range of genetic material present in a gene pool or population of a species

3. Species diversity = variety among species per unit area. Includes both the number of species present and their abundance.

4. Habitat diversity = The range of different habitats or number of ecological niches per unit area in an ecosystem, community or biome. Conservation of habitat diversity usually leads to conservation of species and genetic diversity

Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012

BIODIVERSITAS

• Is key to the overall function of earth• In general Diversity = Stability• Biodiversity is

– Nature’s insurance policy against change– The source of all natural capital for human use– The way chemical materials are cycled and purified– The end result of millions of years of evolution and

irreplaceable


BIODIVERSITAS:SPESIES & PROSES

1. Richness: The number of species per sample is a measure of richness.

The more species present in a sample, the “richer” the sample.

2. Evenness: A measure of the relative abundance of the different species making up the richness of an area.


BIODIVERSITAS

Quantifiying this Diversity – Simpson’s Index

D = N (N – 1)∑ n (n – 1)

• Where D = diversity indexN = total # of organisms of all species n = # of individuals of particular species


• High values of “D” suggests a stable and ancient site• A low value of “D” could suggest pollution, recent

colonization, or agricultural management• Index normally used in studies of vegetation but can be

applied to comparisons of diversity of any species


Quantifiying this Diversity – Simpson’s Index

How does diversity exist?

• Natural Selection = survival of the fittest• Fitness = a measure of reproductive success

• If all individuals are variable• And populations produce large numbers of offspring without

increase in population size• And resources are limited• And traits are heritable

• Then those individuals who are best adapted to the environment will survive and pass on their genes

• Gradually the gene frequency in the population will represent more of these “fit” individualsDiunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012

SELEKSI ALAMIAH• Environmental Pressures select for some genotypes over others• Alleles resulting in a beneficial trait will become more common• Heritable traits that increase survival chances are called

adaptations• There are many niches or habitats and roles available in the

environment• As populations adapt they fill new niches and over time may

develop into new species



Speciation• Certain circumstances lead to the production of new species

through natural selection• Most common mechanism has 2 phases geographic followed

by reproductive isolation

1. Geographic isolation groups of a population of the same species are isolated for long periods– A group may migrate in search of food to an area with different

environmental conditions– Populations may be separated by a physical barrier (mountain range,

river, road)– Catastrophic change by volcano eruption or earthquake– A few individuals carried away by wind or water to new areaDiunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012

Speciation 2

2. Reproductive Isolation mutation and natural selection operate independently on the 2 populations to change allele frequencies = divergence

• If divergence continues long enough genetic differences may prohibit (1) interbreeding between populations and/or (2) production of viable, fertile offspring

• One species has become 2 through divergent evolution• For most species this would take millions of years• Difficult to document & prove this process


Early foxpopulation

Spreadsnorthward

andsouthward

andseparates

Adapted to heatthrough lightweightfur and long ears,

legs, and nose, whichgive off more heat.

Adapted to coldthrough heavierfur, short ears,

short legs, shortnose. White furmatches snowfor camouflage.

Gray Fox

Arctic Fox

Different environmentalconditions lead to different

selective pressures and evolutioninto two different species.

Southern population

Northern population


Consequences of Plate Activity

• Speciation processes rely on physical separation of organisms

• Plate techtonics – can lead to separation of gene pools – mountain ranges

form, faults separating land masses– Can link species and land areas e.g. land bridges


Consequences of Plate Activity II

• Plate techtonics generates new habitats– Island chains over hotspots – Hawaii– Mountain habitats – Himalayan mountains – also

associated effects on surrounding areas– Hydrothermal vent communities– Changes climate on land masses – continents drift into

new climate zones e.g. antarctica was once covered by tropical rainforest now barren polar ice fields


1. Succession effects Diversity

• Succession – gradual establishment or reestablishment of ecosystems over time

• Pioneer species Climax species– Low diversity at first, few species can tolerate harsh conditions (r

selected species)– Most diverse in middle of succession, slower growing species start

to fill in – Low diversity at the end, climax species often strongest

competitors (K selected species)• Diversity is a function of disturbance intermediate

disturbance hypothesisDiunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012

Time

Small herbsand shrubs

Heath mat

Jack pine,black spruce,

and aspen

Balsam fir,paper birch, and

white spruceclimax community

Exposedrocks

Lichensand mosses


1000

Percentage disturbance

Spec

ies

dive

rsity


2. Habitat diversity influences species & genetic diversity

• More complex areas (more diverse habitats) often have higher species & genetic diversity

• Ex. Tropical rainforest & Coral reef• In both cases, high degree of structural / spatial

complexity• Promotes coexistence by niche partitioning &

diversification


Producer to primaryconsumer

Primaryto secondary

consumer

Secondary tohigher-levelconsumer

All producers andconsumers todecomposers

Fungi

Bacteria

Bromeliad

Ants

Tree frog

Green tree snake

Katydid

Climbingmonstera palm

Squirrelmonkeys

Blue andgold macaw

Harpyeagle

Ocelot

Slaty-tailedtrogon

Slaty-tailedtrogon


Harpyeagle

Tocotoucan

Woolyopossum

Braziliantapir

Black-crownedantpitta

Shrub layer

Canopy

Emergentlayer

UnderstoryUnderstory

Groundlayer

Groundlayer0

5

10

15

20

25

30

35

40

45H

eigh

t (m

eter

s)


Complex ecosystems with a variety of nutrient & energy pathways provides stability

• Energy is key to the function of all ecosystems• Biogeochemical cycles recycle necessary materials

through system• More pathways for energy & matter = more stable• Insurance against natural or human changes


Human activities

• Modify succession by adding disturbance• Logging, Grazing, Burning – all prevent natural

successional processes• Fragmenting habitats by development• Isolate populations more likely to get diseases,

succumb to local disturbances• We simplify ecosystems tall grass prairie

converted to wheat farms more vulnerable


HighwayCleared plotsfor grazing

Cleared plotsfor agriculture


Any ecosystem’s capacity to survive change may depend on its diversity, resilience, and inertia


ECOSYSTEM STABILITY

1. The vast majority of natural ecosystems experience regular environmental change, or disturbances.

2. Most ecologists describe ecosystem stability as the ability of an ecosystem to maintain its structure and function over long periods of time and despite disturbances.

3. Ecosystem structure includes physical and geological structures of the landscape, the number and diversity of species present, the population sizes of those species, and the ways in which these populations interact.

4. Ecosystem function refers to processes such as water and nutrient cycling and biomass productivity that the ecosystem provides.

. Sumber: www.aisd.net/aisd/Portals/73/.../12F%20Ecosystem%20Stability.ppt ………… diunduh 19/12/2012

STABILITAS EKOSISTEM

1. There are two main components to ecosystem stability: resistance and resilience.

2. An ecosystem displays resistance if keeps its structure and continues normal functions even when environmental conditions change.

3. An ecosystem displays resilience if, following a disturbance, it eventually regains its normal structure and function.


RESISTENSI & RESILIENSI

1. Ecosystems that show a high degree of stability may have different combinations of resistance and resilience.

2. Research has shown that species diversity is often the key to both ecosystem resistance and resilience.

3. An ecosystem rich in biodiversity will likely be more stable than one whose biodiversity is low.

Infer If an ecosystem has low biodiversity, is it more or less

stable than an ecosystem of high biodiversity? . Sumber: www.aisd.net/aisd/Portals/73/.../12F%20Ecosystem%20Stability.ppt ………… diunduh 19/12/2012


HOW DOES ENVIRONMENTAL CHANGE AFFECT ECOSYSTEM STABILITY?

1. Communities respond to environmental change in ways that reflect the responses of the species and populations in the community.

2. Species respond to environmental change in ways that enable them to maintain homeostasis.

3. Populations respond in ways that reflect the success or failure of members of the population to survive and reproduce.


• Changing environmental conditions can cause the decline of local biodiversity. If this happens, an ecosystem’s resistance and/or resilience may decline. The end result is that the ecosystem loses stability.

• Ecosystems that are less stable may not be able to respond to a normal environmental disturbance, which may damage ecosystem structure, ecosystem function, or both.



How does natural environmental change affect ecosystem stability?

• Fires, heavy storms, and natural climate change can cause major changes in local populations of plants and animals.

• A decline in natural biodiversity can make an ecosystem less stable.

Apply Concepts What is one example of a local natural environmental

change? How did it impact ecosystem stability?


How does environmental change caused by human actions affect ecosystem stability?

1. Humans affect ecosystem stability in many ways, including habitat loss, introduction of nonnative species, release of pollution into food webs, and contribution to climate change.

2. Ecosystems are frequently destroyed for agricultural activity and urban development. Clearing patches of habitat can split ecosystems into pieces, a process called habitat fragmentation.


• Remaining pieces of habitat become habitat “islands” surrounded by a different habitat. The smaller a habitat island is, the fewer species can live there, and the smaller their populations can be.

• A keystone species is one that has a strong and/or wide-reaching impact on a community’s stability. If a keystone species declines in number, the ecosystem becomes much less stable.

Predict Sea otters, a keystone

species, eat sea urchins, which in turn eat kelp. In

the 1990s, sea otter populations off the coast of

Alaska declined because orcas ate large numbers of otters. What effect did this

have on the sea otters’ ecosystem?



1. Humans sometimes introduce organisms into a new habitat, whereit can become invasive and threaten biodiversity and ecosystem structure.

2. An invasive species is a nonnative species that spreads widely in a community. Nonnative species become invasive if their new surroundings lack natural population checks such as predators or competitors.

3. Invasive species usually cause local native biodiversity to decline and therefore affect ecosystem stability.



• Many pollutants, including pesticides and acid rain, impact plant and animal populations. These changes, in turn, threaten biodiversity.

• Organisms are adapted to their environments and have specific tolerance ranges to conditions such as temperature. If conditions change beyond an organism’s tolerance, the organism must move to another location or face extinction.

• Increases in Earth’s average temperatures could affect ecosystem structures and functions.

• Scientists are not yet sure how predicted changes in global climate within the next several decades will affect ecosystem stability worldwide.



ECOSYSTEM PRODUCTIVITY

Food webs, food chains, pyramids – you can also look at ecosystems through their productivity.

Productivity is the rate at which chemical energy is produced in an ecosystem – expressed as ‘gram of

organic matter per square metre per year’

. Sumber: lynclarkson.wikispaces.com/.../4.+ECOSYSTEMS+DIFER+IN+...………… diunduh 19/12/2012

PRODUKTIVITAS EKOSISTEM

1.Gross primary productivity (GPP) is the rate at which an ecosystem's producers convert solar energy into chemical energy as biomass.

2. Net primary productivity (NPP) is the rate at which energy for use by consumers is stored in new biomass.

NPP = GPP – R [rate at which producers use biomass]


PRODUKTIVITAS PRIMER EKOSISTEM

Generally ecosystems with the highest net productivity are those with the greatest accumulated producer biomass

The higher the net primary production of an ecosystem, the more food is available for consumer organisms and the greater the biomass of consumers living in that ecosystem.

More produ

cer biomass

More photosynthesi

s

More chemi

cal energ

y stored

in organi

c matter


PRODUKTIVITAS EKOSISTEM

WHY DO PRODUCTION RATES DIFFER?

1. Why does a desert ecosystem have a lower productivity than a tropical rainforest?

2. What affects do temperature and hours of sunlight have on productivity?

3. List some limiting factors for ecosystems?4. Explain why Australia does not have rich fishing

grounds near its coast.


AN ECOSYSTEM IN DARKNESS1. If light is needed for photosynthesis, but does not penetrate to the depths of the

ocean, how does a consumer in ocean darkness feed?2. Explain how producers can exist in the dark depths of the ocean.3. Explain the difference between photosynthetic organisms and chemosynthetic

organisms.4. What is the energy source for photosynthetic organisms? What is the waste

product?5. What is the energy source for chemosynthetic organisms? What is the waste

product?


KEY ENERGY PROCESSES• Photosynthesis: use of chlorophyll. Energy storing process.

– 6 CO2 + 6 H2O + solar energy C6H12O6 + 6 O2

• Cellular Respiration:– Aerobic Respiration: energy releasing process.– C6H12O6 + 6 O2 6CO2 + 6 H2O + energy (ATP)

• Anaerobic Respiration – Ex. Fermentation: energy releasing process used by yeast and

bacteria


PRIMARY PRODUCTION AND ENERGY FLOW

ENERGY FLOWS: solar (or nuclear)

input heat output

NUTRIENTS RECYCLE: mass

conservation inorganic ↔

organic

. Sumber: www2.yk.psu.edu/~mph13/EnergyFlow.18.ppt...………… diunduh 19/12/2012

TINGKAT TROFIK• Trophic Level: Position in a food web determined by number of

energy transfers from primary producers to current level:– Primary producers occupy first level.– Primary consumers occupy second level.– Secondary consumers occupy third level.– Tertiary consumers occupy fourth level.



PRODUSEN – KONSUMEN

• Primary production: Fixation of energy by autotrophs in an ecosystem.– Rate of primary production: Amount of energy fixed

over a given period of time.• Gross primary production: Total amount of energy fixed

by autotrophs.• Net primary production: Amount of energy leftover after

autotrophs have met their metabolic needs.


PRODUKSI PRIMER

• Bottom-Up Controls– Influences of physical and chemical factors of an ecosystem.

• Top-Down Controls– Influences of consumers.


KONTROLPRODUKSI PRIMER

Actual Evapotranspiration and Terrestrial Primary Production

• Rosenzweig estimated influence of moisture and temperature on rates of primary production by plotting relationship between annual net primary production and annual actual evapotranspiration (AET).– AET: Annual amount of water that evaporates and transpires

off a landscape.• Cold dry ecosystems tend to have low AET.


Evapotranspiration & Terrestrial Primary Production



PRODUKSI PRIMER NETO

• Significant variation in terrestrial primary production can be explained by differences in soil fertility.– Shaver and Chapin found arctic net primary production was twice as

high on fertilized plots as unfertilized plots.– Bowman suggested N is main nutrient limiting net primary production

in a dry tundra meadow, and N and P jointly limit production in a wet meadow.


PRODUKSI PRIMER & KESUBURAN TANAH


PRODUKSI PRIMER NETO


PRODUKSI PRIMER

POLA PRODUKSI PRIMER AKUATIK

• Several studies have found quantitative relationship between phosphorus and freshwater phytoplankton biomass.

• Several studies support generalization that nutrient availability controls rate of primary production in freshwater ecosystems.



PRODUKSI PRIMER BIOMASA ALGAE

Carpenter proposed piscivores and planktivorous fish can cause significant deviations in primary productivity.

– Carpenter and Kitchell proposed the influence of consumers on lake primary productivity propagate through food webs.

• Trophic Cascade Hypothesis


PRODUKSI PRIMERDANAU


PRODUKSI PRIMER DANAU





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