Ecosystems and Ecosystems and CommunitiesCommunities

Chapter 20Chapter 20

The role of ClimateThe role of Climate

What is climate?What is climate?– Temperature, precipitation, other Temperature, precipitation, other

environmental factors combine to environmental factors combine to produce weather and climate.produce weather and climate.

Greenhouse EffectGreenhouse Effect

This is a This is a naturalnatural situation!!situation!!

Carbon dioxide, Carbon dioxide, methane, water methane, water vapor and other vapor and other gases trap heat gases trap heat energy and energy and maintain the maintain the EarthEarth’’s s temperature rangetemperature range

The Effect of Latitude on climateThe Effect of Latitude on climate

How does the position of the sun in How does the position of the sun in the sky effect climate? (the sky effect climate? (see the next see the next slide for the answer)slide for the answer)

The Earth has three main climate The Earth has three main climate zones:zones:

polarpolartemperatetemperatetropicaltropical

Different latitudes have different Different latitudes have different angles of heating, affecting climateangles of heating, affecting climate

Heat Transport in the BiosphereHeat Transport in the Biosphere

Unequal heating and cooling drives winds Unequal heating and cooling drives winds and ocean currents.and ocean currents.

What Shapes an Ecosystem?What Shapes an Ecosystem?

Key conceptKey concept: Biotic and abiotic : Biotic and abiotic factors determine the survival and factors determine the survival and growth of and organism and the growth of and organism and the productivity of the ecosystem in productivity of the ecosystem in which the organism lives.which the organism lives.

Biotic FactorsBiotic Factors– All living things in All living things in

an ecosysteman ecosystem

Abiotic FactorsAbiotic Factors– Temperature,Temperature,– PrecipitationPrecipitation– HumidityHumidity– WindWind– Nutrient availabilityNutrient availability– Soil type Soil type – SunlightSunlight

The NicheThe Niche

An organisms occupation in its An organisms occupation in its environment is itenvironment is it’’s s niche.niche.

This includes the following factorsThis includes the following factors– Type of foodType of food– How it obtains foodHow it obtains food– Which other species use the organism Which other species use the organism

as foodas food– Physical conditions.Physical conditions.

WARNING WARNING WARNINGWARNING

No two species No two species can share the can share the

same niche in the same niche in the same habitat.same habitat.

CommunityCommunity InteractionsInteractions

Community interaction, such as Community interaction, such as competition, predation and various competition, predation and various forms of symbiosis can powerfully forms of symbiosis can powerfully affect an ecosystemaffect an ecosystem

CompetitionCompetition– Happen when two Happen when two

organisms try to organisms try to use the same use the same resource in the resource in the same place at the same place at the same timesame time

– AA Resource Resource is: is: water, nutrients, water, nutrients, light food, or space.light food, or space.

Competitive Competitive Exclusion PrincipleExclusion Principle– No two species can No two species can

occupy the same occupy the same niche in the same niche in the same habitat at the same habitat at the same time!!!time!!!

PredationPredation

An interaction in which one organism An interaction in which one organism captures and feeds on another.captures and feeds on another.

Symbiosis: Living together closelySymbiosis: Living together closely

MutualismMutualism: : both both species species benefitbenefit

+/++/+

CommensalismCommensalism

One member One member benefits and benefits and the other is the other is neither neither helped nor helped nor harmedharmed

+/0+/0

ParasitismParasitism

One organism One organism lives on or lives on or inside another inside another organisms and organisms and harms it.harms it.

+/-+/-

Patterns in CommunitiesPatterns in Communities

Species richnessSpecies richness– The number of The number of

species in the species in the communitycommunity

– A simple count of A simple count of the species in a the species in a communitycommunity

Species Species evennessevenness– The relative The relative

abundance of abundance of each species.each species.

– How common How common each species is.each species is.

Latitude and species richnessLatitude and species richness

Species richness Species richness varies with varies with distance from distance from equator—closer equator—closer to equator = to equator = more speciesmore species

Habitat size: Habitat size: greater the area greater the area will contain more will contain more species than a species than a small area.small area.

Species Species interactions will interactions will affect species affect species richnessrichness

Species richness Species richness influences how a influences how a community community responds to a responds to a disturbance.disturbance.

Ecological SuccessionEcological Succession

Ecosystems are constantly changing Ecosystems are constantly changing in response to natural and human in response to natural and human disturbances.disturbances.

As an ecosystem changes, older As an ecosystem changes, older inhabitants gradually die out and inhabitants gradually die out and new organisms move in, causing new organisms move in, causing further changes in the communityfurther changes in the community

The series of predictable changes The series of predictable changes that occur in a community over that occur in a community over

time.time. Primary successionPrimary succession

– Succession that Succession that occurs on surfaces occurs on surfaces where no soil where no soil exists.exists.

Primary successionPrimary succession

Occurs on the surfaces formed as Occurs on the surfaces formed as volcanic activity builds new islands or volcanic activity builds new islands or covers the land with lava or volcanic covers the land with lava or volcanic ash.ash.

Also occurs on bare rock exposed Also occurs on bare rock exposed when glaciers melt.when glaciers melt.

The first species to populate an area: The first species to populate an area: pioneer speciespioneer species

Secondary SuccessionSecondary Succession

A disturbance of some kind that A disturbance of some kind that changes an existing community changes an existing community without removing the soil.without removing the soil.

Caused by farming, wildfiresCaused by farming, wildfires The series of predictable changes The series of predictable changes

ends with a mature, stable ends with a mature, stable community called a community called a climax climax communitycommunity

Climax communityClimax community

Secondary SuccessionSecondary Succession

BiomesBiomes

There are at least 10 different There are at least 10 different biomes.biomes.

Each of these biomes is defined by a Each of these biomes is defined by a unique set of abiotic factors and has unique set of abiotic factors and has a characteristic ecological a characteristic ecological communitycommunity

What is this biome?What is this biome?

What biome is this?What biome is this?

Name That Biome!!Name That Biome!!

What biome is this?What biome is this?

Last but not least…Last but not least…

Water, water everywhere…Water, water everywhere…

Aquatic ecosystems are determined Aquatic ecosystems are determined primarily by the depth, temperature, primarily by the depth, temperature, flow, and chemistry of the overlying flow, and chemistry of the overlying water.water.

Freshwater ecosystemsFreshwater ecosystems

Flowing waterFlowing water: rivers and streams : rivers and streams Standing waterStanding water: lakes and ponds: lakes and ponds WetlandsWetlands: marshes and swamps: marshes and swamps EstuariesEstuaries: where rivers meet the sea. : where rivers meet the sea.

– Contain a mixture of fresh and salt waterContain a mixture of fresh and salt water– Salt marshes and mangrove swamps are Salt marshes and mangrove swamps are

examples.examples.

Marine EcosystemsMarine Ecosystems

Divided into two zones based on the Divided into two zones based on the amount of light penetration.amount of light penetration.– Photic zonePhotic zone: well-lit upper layer down to : well-lit upper layer down to

about 200 meters. Photosynthesis about 200 meters. Photosynthesis possible.possible.

– Aphotic zoneAphotic zone: permanently dark. Only : permanently dark. Only producers in this zone are producers in this zone are chemoautotrophs.chemoautotrophs.

Marine ecosystems continued.Marine ecosystems continued.

Scientists also divide the ocean into Scientists also divide the ocean into zones based on the depth and zones based on the depth and distance from shore.distance from shore.– IntertidalIntertidal: subject to tides: subject to tides– Coastal oceanCoastal ocean: from the low tide mark to : from the low tide mark to

the edge of the continental shelf. the edge of the continental shelf. Contain coral reefs in tropical areas.Contain coral reefs in tropical areas.

Marine ecosystems cont.Marine ecosystems cont.

Open OceanOpen Ocean: from the continental : from the continental shelf and extends outwardshelf and extends outward– Largest marine zoneLargest marine zone– Organisms in the deep open ocean have Organisms in the deep open ocean have

adapted to great pressure, freezing adapted to great pressure, freezing temperatures and no lighttemperatures and no light

Benthic ZoneBenthic Zone: the ocean floor.: the ocean floor.