Chapter 04 Ecosystems and Communities

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Chapter 04

Ecosystems and Communities


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4-1 The Role of Climate

At the conclusion of this section, you

should be able to answer the following

questions:

How does the greenhouse effect maintain the

biosphere's temperature range?

What are Earth's three main climate zones?


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4-1 The Role of Climate Key Terms

Weather

condition of Earth's atmosphere at a particular time and place

Climate

average, year-after-year conditions of temperature andprecipitation in a particular region

Greenhouse Effect

natural situation in which heat is retained in Earth's

atmosphere by carbon dioxide, methane, water vapor, and

other gases


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4-1 The Role of Climate Key Terms

Polar Zone cold climate zone where the sun's rays strike Earth at

a very low angle.

Temperate zone moderate climate zone between the polar zones and

the tropics

Tropical zonewarm climate zone that receives direct or nearly

direct sunlight year round


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Climate

In the atmosphere, temperature, precipitation,

and other environmental factors combine to

produce weather and climate.

Weather is the day-to-day condition of Earth's

atmosphere at a particular time and place.

Climate on the other hand, refers to the average,

year-after-year conditions of temperature and

precipitation in a particular region.


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Climate

Climate is caused by the interplay of many

factors, including the trapping of heat by the

atmosphere, the latitude, the transport of heat

by winds and ocean currents, and the amount ofprecipitation that results.

The shape and elevation of landmasses also

contribute to global climate patterns.
http://oceancurrents.rsmas.miami.edu/atlantic/atlantic.html


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http://oceancurrents.rsmas.miami.edu/atlantic/atlantic.html


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Solar Energy & Climate

The energy of incoming sunlight drives Earth's

weather and helps determine climate.

Solar energy has an important effect on the

temperature of the atmosphere.

At the same time, the presence of certain gases

(greenhouse gasses like CO2) in the atmosphere

also has an effect on its temperature.


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The Greenhouse Effect

Carbon dioxide

(CO2), methane (CH4),

water vapor (H2O), and

a few otheratmospheric gases trap

heat energy and

maintain Earth's

temperature range.


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The Greenhouse Effect

Greenhouse gases allow solar energy to

penetrate the atmosphere in the form of

sunlight. Much of the sunlight that hits the

surface of our planet is converted into heatenergy and then radiated back into the

atmosphere.


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The Effect of Latitude on Climate

Earth is a sphere that is

tilted on its axis.

We are tilted about 23.5

degrees off 90.


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Climate Zones

Earth has three main climate zones.These climate zones are caused by the unequal

heating of Earth's surface.

Near the equator, energy from the sun strikes Earthalmost directly.

Near the poles, the sun's rays strike Earth's surfaceat a lower angle.

The same amount of solar energy is spread out overa larger area, heating the surface less than at theequator.


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Earths 3 Main Climate Zones

As a result of differences in latitude and thus the

angle of heating, Earth has three main climate

zones: polar, temperate, and tropical.

Polar Zones

cold areas where the sun's rays strike Earth at a very

low angle. These zones are located in the areas

around the North and South poles, between 66.5and 90 North and South latitudes.


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Earths 3 Main Climate Zones

Temperate Zones

sit between the polar zones and the tropics. Because

temperate zones are more affected by the changing angle of

the sun over the course of a year, the climate in these zonesranges from hot to cold, depending on the season.

Tropical Zones

near the equator, between 23.5 North and 23.5 South

latitudes. The tropics thus receive direct or nearly directsunlight year-round, making the climate almost always warm.


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H AT TRANSPORT IN TH BIOSPH R


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HEAT TRANSPORT IN THE BIOSPHERE


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Heat Transport in the Biosphere


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4-2 What Shapes an Ecosystem?

At the conclusion of this section, you

should be able to answer the following

questions:

How do biotic and abiotic factors influence an

ecosystem?

What interactions occur within communities?

What is ecological succession?


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4-2 What Shapes an Ecosystem? Key

Terms

Biotic factor biological influence on organisms within an

ecosystem

Abiotic Factor physical, or nonliving, factor that shapes an

ecosystem

Habitat the area where an organism lives, including the biotic

and abiotic factors that affect it


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Terms

Niche

full range of physical and biological conditions in which an

organism lives and the way in which the organism uses those

conditions

Resource

any necessity of life, such as water, nutrients, light, food, or

space

Competitive Exclusion Principle ecological rule that states that no two species can occupy the

same exact niche in the same habitat at the same time


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Terms

Predation interaction in which one organism captures and

feeds on another organism

Symbiosis relationship in which two species live closely

together

Mutualism symbiotic relationship in which both species benefit

from the relationship


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Terms

Commensalism

symbiotic relationship in which one member of the

association benefits and the other is neither helped

nor harmed

Parasitism

symbiotic relationship in which one organism lives in

or on another organism (the host) and consequentlyharms it


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Terms

Ecological Succession gradual change in living communities that follows a

disturbance

Primary Succession succession that occurs on surfaces where no soil exists

Pioneer Species first species to populate an area during primary succession

Secondary Succession succession following a disturbance that destroys a community

without destroying the soil


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Lets think about Ecology

Think about your house.

You do not exist in your

house alone

There are numerous

things living and non

living, both inside and

outside your house that

affect you
http://www.beloit.edu/~pubaff/virtualtour/Guest-House.jpg


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Lets look at some living

examples Your Parents may

control

What you eat

Curfews & Bed times Allowance

Privileges


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Some more living examples

Brothers and Sisters

may affect

Your allowance

Your duties aroundthe house

How much trouble you

get in

Your free time


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Outside your house

Neighbors may affect

How loud you play

your music

Your pets, if they barkall night

The appearance of

your house.


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There are non living factors

too. What kind of

neighborhood do youlive in?

Do you have to travela long way to getfood or water?

Is your neighborhood

sanitary?


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More non living factors

Do you havenumerous publicservices available? Police, Fire,

Ambulance etc?

Are there numerousoptions available toyou for almost

anything you canthink of?


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Finally

Do you live in an area

where there is

constant war or

fighting? An area subject to

frequent floods,

tornadoes,

hurricanes,earthquakes, or

volcanoes?


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Apply this to ecology

Ecology applies to this example.

You interact with parents, siblings, andneighbors. They all influence you, and

you influence them too. Non living factors also play a role in your

growth and development. Safety,

Security, and Sanitation are threeimportant factors.


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Abiotic Factors in this

ecosystem Temperature

Rainfall

Sunlight Soil Type & pH

Rocks

Elevation Humidity


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Biotic Factors in this

ecosystem Birds

Fish

Plants, trees, shrubs, grasses and aquaticplants

Molds and Fungi

Bacteria Insects


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Biotic & Abiotic Factors in the

Ecosystem

Together, biotic and abiotic factors

determine the survival and growth of an

organism and the productivity of the

ecosystem in which the organism lives


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The Niche

If an organism's habitat is its address, its niche is

its occupation.

A niche (NITCH) is the full range of physical

and biological conditions in which an organism

lives and the way in which the organism uses

those conditions.


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The Niche

A niche includes the type of food the organism

eats, how it obtains this food, and which other

species use the organism as food.

The physical conditions that the organism

requires to survive are part of its niche.

The organism's niche also includes when and

how it reproduces.


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The Niche

No two species can share the same niche in the

same habitat. However, different species can

occupy niches that are very similar. For instance,

the three species of North American warblersshown in the figure at right live in the same

spruce trees but feed at different elevations and

in different parts of those trees. The species aresimilar, yet each warbler has a different niche

within the forest.


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Community Interactions

Key Concept:

Community interactions, such as competition,

predation, and various forms of symbiosis, can

powerfully affect an ecosystem.


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Competition

Competition occurs when organisms of thesame or different species attempt to use anecological resource in the same place at the same

time.The term resource refers to any necessity of life,

such as water, nutrients, light, food, or space

Direct competition in nature often results in awinner and a loserwith the losing organismfailing to survive.


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The Competitive Exclusion Principle

also called Gause's principle, or Grinnell'saxiom (after G.F. Gause, a Soviet biologist, andJ. Grinnell, an American naturalist, who first

clearly established it), statement that incompetition between species that seek the sameecological niche, one species survives while theother expires under a given set of environmental

conditions. The result is that each speciesoccupies a distinct niche.

competitive exclusion, principle of." Encyclopdia Britannica. 2007. EncyclopdiaBritannica Online. 11 Oct. 2007 .
http://www.britannica.com/eb/article-9000695http://www.britannica.com/eb/article-9000695http://www.britannica.com/eb/article-9000695http://www.britannica.com/eb/article-9000695


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Predation

An interaction in which one organism captures

and feeds on another organism.

The organism that does the killing and eating is

called the predator (PRED-uh-tur), and the food

organism is the prey.


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Symbiosis

means living together.

Any of several living arrangements between membersof two different species, including mutualism,commensalism, and parasitism. Both positive(beneficial) and negative (unfavorable to harmful)associations are therefore included, and the membersare called symbionts.

Any association between two species populations thatlive together is symbiotic, whether the species benefit,harm, or have no effect on one another.

"symbiosis." Encyclopdia Britannica. 2007. Encyclopdia Britannica Online.

11 Oct. 2007 .
http://www.britannica.com/eb/article-9070714http://www.britannica.com/eb/article-9070714http://www.britannica.com/eb/article-9070714http://www.britannica.com/eb/article-9070714


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Mutualism


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Mutualism

In mutualism (MYOO-choo-ul-iz-um), both

species benefit from the relationship.

The ant cares for the aphids and protects them

from predators. The aphids produce a sweetliquid that the ant drinks.


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Commensalism


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Commensalism

In commensalism (kuh-MEN-sul-iz-um), one

member of the association benefits and the

other is neither helped nor harmed.

The orchid benefits from its perch in the tree asit absorbs water and minerals from rainwater

and runoff, but the tree is not affected.


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Parasitism


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Parasitism

A tick feeds on the blood of its host and mayalso carry disease-causing microorganisms.

Inparasitism (PAR-uh-sit-iz-um), one

organism lives on or inside another organismand harms it. The parasite obtains all or part ofits nutritional needs from the other organism,called the host. Generally, parasites weaken but

do not kill their host, which is usually larger thanthe parasite.


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Ecological Succession

The development of communities over

time.

Continuous changes in structure and

composition until a dynamic equilibriumis reached.


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Ecological Succession

A process by which an existing community

of organisms is replaced by a different

community over periods of time ranging

from a few decades to thousands ofyears.


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Primary Succession

Primary succession This is when succession is started by the formation

of totally new land. This may happen naturally or becaused by humans (Anthropogenic). New land is

referring to a newly formed land mass such as avolcanic island. When first formed these consist ofpure rocks. Plants (flora) can not live here and so noanimal life (fauna) can live here. These islands arevery inhospitable are identified mostly by a almost

total lack of soil.

http://www.restoringearth.co.uk/education/a-level/science/environmental_science/ecology/succession/succession.htm
http://www.restoringearth.co.uk/deff/anthropogenic.htmhttp://www.restoringearth.co.uk/deff/flora.htmhttp://www.restoringearth.co.uk/deff/fauna.htmhttp://www.restoringearth.co.uk/deff/fauna.htmhttp://www.restoringearth.co.uk/deff/flora.htmhttp://www.restoringearth.co.uk/deff/anthropogenic.htm


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Primary Succession

Over a period of time a thin layer of soil mayform by the processes of weathering. Somebacteria and Lichens (Lichens) may alreadyhave already colonized the rocks by absorbing

nutrients from the rocks. But it is not until thisfirst weathering has formed the thin soil thatsuccession really starts. At this point mossesand ferns are able to grow. These mosses and

ferns dominate the area and the Lichens die.


osses an c ens
http://www.restoringearth.co.uk/deff/lichens.htmhttp://www.restoringearth.co.uk/deff/lichens.htm


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osses an c ensdemonstrate ecological

succession


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Lichens breaking down rock


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Mosses on Rock


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Primary Succession

Many of these early plants are Legumes(legumes) and this helps to fertilize the soil.When the soil becomes more fertile andthicker, due to humus (Humus) and more

weathering of the Bedrock/regolith, other floracan colonize the area. As the plant life changesso does the fauna/animals that live in the area.The life present will change many times and we

called these stages a seral stage (seral stage).The whole process for a particular ecosystem isknown as its sere (sere).

http://www.restoringearth.co.uk/deff/legumes.htmhttp://www.restoringearth.co.uk/deff/humus.htmhttp://www.restoringearth.co.uk/deff/seral-stage.htmhttp://www.restoringearth.co.uk/deff/sere.htmhttp://www.restoringearth.co.uk/deff/sere.htmhttp://www.restoringearth.co.uk/deff/seral-stage.htmhttp://www.restoringearth.co.uk/deff/humus.htmhttp://www.restoringearth.co.uk/deff/legumes.htm


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Succession ends when a climax community isreached. A climax community is normally aforest ecosystem as trees are the most efficientat using sunlight. However in areas that have to

low or to high amounts of insulation (insulation)may have different climax communities. Theycould be described as ecosystems that havereached the carrying capacity (carrying

capacity) of their environment.


Primary Succession
http://www.restoringearth.co.uk/deff/insulation.htmhttp://www.restoringearth.co.uk/deff/carrying-capacity.htmhttp://www.restoringearth.co.uk/deff/carrying-capacity.htmhttp://www.restoringearth.co.uk/deff/carrying-capacity.htmhttp://www.restoringearth.co.uk/deff/carrying-capacity.htmhttp://www.restoringearth.co.uk/deff/insulation.htm


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Primary Succession

Primary succession

showing the

movement from no

life, to pioneerspecies, to small

plants and shrubs, to

conifers, eventually

to a climaxcommunity.



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Secondary Succession

This is much the same as Primary

succession except it occurs when the

current seral stage (seral stage) is

removed abruptly. This may be due to anatural disaster such as an earthquake or

volcanic eruption, or by anthropogenic

(Anthropogenic) effects such asdeforestation and strip mining.

http://www.restoringearth.co.uk/deff/seral-stage.htmhttp://www.restoringearth.co.uk/deff/anthropogenic.htmhttp://www.restoringearth.co.uk/deff/anthropogenic.htmhttp://www.restoringearth.co.uk/deff/seral-stage.htm


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This time there is already soil and probablyseeds present. This means the succession willhappen more rapidly than primary succession.Wind blown plants that are tolerant to high

levels of sun and grow fast called pioneer orfugitive species will colonize the area. Thesewill then be replaced by herbaceous(herbaceous) plants, which will then be

followed by bush like plants and trees if theecosystem can support such flora.


http://www.restoringearth.co.uk/deff/herbaceous.htmhttp://www.restoringearth.co.uk/deff/herbaceous.htm


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These types of succession are known as

autogenic (autogenic).

In some cases allogenic succession (allogenic

succession) may occur. For example a lake maysilt up (silt up) over time to eventually produce

a terrestrial (terrestrial) environment.

Autogenic succession may then occur on this

new land.


http://www.restoringearth.co.uk/deff/autogenic.htmhttp://www.restoringearth.co.uk/deff/allogenic-succession.htmhttp://www.restoringearth.co.uk/deff/allogenic-succession.htmhttp://www.restoringearth.co.uk/deff/silt-up.htmhttp://www.restoringearth.co.uk/deff/terrestrial.htmhttp://www.restoringearth.co.uk/deff/terrestrial.htmhttp://www.restoringearth.co.uk/deff/silt-up.htmhttp://www.restoringearth.co.uk/deff/allogenic-succession.htmhttp://www.restoringearth.co.uk/deff/allogenic-succession.htmhttp://www.restoringearth.co.uk/deff/autogenic.htm


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The illustration showsa major disturbance(fire) removing thecurrent seral stage

abruptly. Succession occurs

again rapidly due toalready established

soil.



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http://io.uwinnipeg.ca/~simmons/Chap5398/sld002.htm

Mt St Helens & Secondary


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Mt. St. Helens & Secondary

Succession At 8:32 Sunday morning, May 18, 1980, Mount St.

Helens erupted.

Shaken by an earthquake measuring 5.1 on the Richter

scale, the north face of this tall symmetrical mountain

collapsed in a massive rock debris avalanche. Nearly230 square miles of forest was blown over or left dead

and standing.

Mt. St. Helens

& Secondary


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At the same time a mushroom-shaped column of ashrose thousands of feet skyward and drifted downwind,

turning day into night as dark, gray ash fell over

eastern Washington and beyond.

The eruption lasted 9 hours, but Mount St. Helens andthe surrounding landscape were dramatically changed

within moments.


Succession

Mt. St. Helens

& Secondary


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Blown down forest protected by snow

near Meta Lake. Snow protected Pacific

silver fir and mountain hemlock trees

near Meta Lake three years after theeruption. Re-sprouting shrubs are also

visible.

Mt. St. ele s & Seco da y

Succession



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. . y

Succession

Mt. St. Helens

& Secondary


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Same view of blown down forest near

Meta Lake nine years after the eruption.

Note that the snow-protected trees have

grown and numerous snow-protectedshrubs have also re-sprouted.

y

Succession



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y

Succession

Mt St Helens & Secondary


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Succession Same view of blown down forest near

Meta Lake 14 years after the eruption.

Note the comparative large size and

continued growth of the snow-protectedtrees and shrubs.



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y

Succession


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Climax Community

The final stage of biotic successionattainable by a plant community in anarea under the environmental conditions

present at a particular time. The speciescomposition of the community remainsthe same because all the species presentsuccessfully reproduce themselves and

invading species fail to gain a foothold.

l


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Climax Community

A climax community is a more or lesspermanent and final stage of a particular

succession, often characteristic of a

restricted area.

http://www.uic.edu/classes/bios/bios101/communitie/sld028.htm


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Climax communities are characterized byslow rates of change, compared with

more dynamic, earlier stages.

They are dominated by species tolerantof competition for resources.

Climax Community



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Succession can take a long time.

For example, old field succession may require

100 300 years to reach climax community. But

in this time frame, the probability that aphysical disturbance (fire, hurricane, flood) will

occur becomes so high, the process of

succession may never reach completion.


Climax Community

Questions for your


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Questions for your

consideration Define ecology, biosphere, and ecosystem.

How are they related to one another?

What are biotic factors? Abiotic factors?

Describe the process of ecological succession.

What is a climax community?

How would the breakdown of large amounts oforganic matter upset the natural balance of a

lake ecosystem?

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Chapter 04 Ecosystems and Communities