Understanding Ecosystems

Understanding EcosystemsUnderstanding Ecosystems

Eric StormerEric StormerVirginia Cooperative ExtensionVirginia Cooperative Extension

What is the role of ecology?What is the role of ecology? Ecology is the study of how living Ecology is the study of how living

organisms exist in the organisms exist in the environmentenvironment .. The The biospherebiosphere is the area of the earth is the area of the earth

that supports life.that supports life.

BIOSPHEREBIOSPHERE

What is the role of ecology?What is the role of ecology? An An ecosystemecosystem is a self-contained living is a self-contained living

system.system.– The biotic portion of an ecosystem is The biotic portion of an ecosystem is l ivingliving ..– The abiotic portion is The abiotic portion is non-livingnon-living ..– The biotic portion relies on the The biotic portion relies on the abioticabiotic

portion.portion.– The biotic portion of the ecosystem may rely The biotic portion of the ecosystem may rely

on other biotic factors.on other biotic factors.

Community organization, structure Community organization, structure and food chains.and food chains.

A A communitycommunity is the collection of plants is the collection of plants and animals that live together.and animals that live together.

The natural home of a plant or animal is The natural home of a plant or animal is called its called its habitathabitat ..– The interactions of The interactions of bioticbiotic and and abioticabiotic factors factors

form habitats.form habitats.– Habitats may be terrestrial (land), aquatic Habitats may be terrestrial (land), aquatic

(water) or a (water) or a combinationcombination (wetland). (wetland).– A A changechange in a portion of the habitat affects in a portion of the habitat affects

all organisms present.all organisms present.


A A nicheniche is the special way of living that an is the special way of living that an organism has in a community.organism has in a community.– It includes food, shelter, way of life and It includes food, shelter, way of life and

relationshipsrelationships ..– Each Each organism organism makes unique contributions makes unique contributions

to its habitat.to its habitat.


The The food chainfood chain is the sequence in which is the sequence in which living organisms in a community obtain living organisms in a community obtain their food.their food.– Organisms that make food through Organisms that make food through

photosynthesis are called photosynthesis are called producersproducers ..– TransformersTransformers are organisms that take in are organisms that take in

producers and synthesize more complex producers and synthesize more complex forms of food.forms of food.

– Decomposers are organisms that break down Decomposers are organisms that break down organic materials into their constituents for re-organic materials into their constituents for re-use by the environment.use by the environment.


Feeding groups are segments of a food Feeding groups are segments of a food chain that consume certain types of food.chain that consume certain types of food.– Herbivores Herbivores are animals that only eat plants.are animals that only eat plants.– CarnivoresCarnivores are animals that only eat the are animals that only eat the

flesh of other animals.flesh of other animals.– OmnivoresOmnivores are animals that eat both plants are animals that eat both plants

and animals.and animals.

Natural Selection and SuccessionNatural Selection and Succession

Organisms must Organisms must adaptadapt to changes in to changes in their environment in order to survive.their environment in order to survive.

Natural selectionNatural selection is when life form that is when life form that are best adapted to their environment are best adapted to their environment survive longer and leave more offspring.survive longer and leave more offspring.– AdaptationAdaptation occurs when species tolerate occurs when species tolerate

changes in their environment.changes in their environment.– AdvantageousAdvantageous traits are emphasized in traits are emphasized in

natural selection, i.e., more dominant features natural selection, i.e., more dominant features are passed to offspring.are passed to offspring.


Succession is replacement of one Succession is replacement of one community with another.community with another.– The The species species with the lowest biomass grows with the lowest biomass grows

first.first.– The speed of succession is controlled by The speed of succession is controlled by

naturalnatural events and/or interference by events and/or interference by man/humansman/humans ..

HomeostasisHomeostasis The ability of an organism to maintain a The ability of an organism to maintain a

fairly constant fairly constant internalinternal environment, when environment, when the the externalexternal environment changes, is environment changes, is called called homeostasishomeostasis ..

The environment around an organism is The environment around an organism is dynamic; characterized by vigorous dynamic; characterized by vigorous activity or undergoing activity or undergoing progressprogress and and changechange ..


The organism is affected by:The organism is affected by:– ClimateClimate– MoistureMoisture– TemperatureTemperature– LightLight– SoilSoil– PeriodicityPeriodicity – when things occur at regular – when things occur at regular

intervals.intervals.

SUCCESSIONSUCCESSION

Population ecology and trends Population ecology and trends affecting population growth.affecting population growth.

Population ecologyPopulation ecology is the study of how is the study of how populations of organisms affect each other populations of organisms affect each other in a community.in a community.

Population Ecology consists of three Population Ecology consists of three primaryprimary factors. factors.– A A higherhigher density means more competition for density means more competition for

resources.resources.– WeakerWeaker individuals may not survive in areas individuals may not survive in areas

of of high high density.density.


The age of a population is classified as:The age of a population is classified as:– Prereproductive Prereproductive – young organisms not yet – young organisms not yet

reproducing.reproducing.– ReproductiveReproductive – age at which reproduction – age at which reproduction

occurs.occurs.– Postreproductive Postreproductive – past normal age of – past normal age of

reproduction.reproduction.


Distribution describes the spatial relation Distribution describes the spatial relation between organisms in the community.between organisms in the community.– Some organisms will Some organisms will cluster cluster together (i.e., together (i.e.,

squirrels)squirrels)– Some Some scatteringscattering is often needed. is often needed.


Population Growth studies the natural Population Growth studies the natural trends in the population of a trends in the population of a communitycommunity ..– ImmigrationImmigration is the process by which is the process by which

organisms move organisms move intointo a community. a community.– EmigrationEmigration is the process by which is the process by which

organisms move organisms move out ofout of a community. a community.– NatalityNatality refers to the production of new refers to the production of new

individuals in a community.individuals in a community.– Mortali tyMortali ty describes the death rate of a describes the death rate of a

community.community.


Predation is defined Predation is defined as one living as one living organism serving as organism serving as foodfood for another. for another.


Competit ionCompetit ion occurs when organisms occurs when organisms share the same common resources to live.share the same common resources to live.– Increased competition may Increased competition may stuntstunt growth, ex., growth, ex.,

Key Deer.Key Deer.– Competition may be created by increasing Competition may be created by increasing

population population densitydensity – the concentration of – the concentration of people or organisms within an area in relation people or organisms within an area in relation to size.to size.

KEY DEERKEY DEER

Distinguishing Between BiomesDistinguishing Between Biomes BiomesBiomes are unique combinations of are unique combinations of

plants and animals.plants and animals. There are five major There are five major terrestrialterrestrial biomes. biomes.

– TropicalTropical forests are characterized by a forests are characterized by a warm, wet climate.warm, wet climate.

– TemperateTemperate forests are common forests in forests are common forests in the U.S. The climate of these forests has a the U.S. The climate of these forests has a range of temperatures within moderate limits.range of temperatures within moderate limits.

Distinguishing Between BiomesDistinguishing Between Biomes The Five major terrestrial biomes, cont’d.The Five major terrestrial biomes, cont’d.

– GrasslandsGrasslands and and savannassavannas are areas are areas where grasses normally grow in abundance.where grasses normally grow in abundance.

– TundraTundra is characterized by is characterized by lowlow temperatures temperatures and a and a shortshort growing season. It is level or growing season. It is level or nearly level of treeless plain between the ice nearly level of treeless plain between the ice cap and the timber line of North America and cap and the timber line of North America and Eurasia that has permanently frozen subsoil. Eurasia that has permanently frozen subsoil.

Distinguishing Between BiomesDistinguishing Between Biomes The Five major terrestrial biomes, cont’d.The Five major terrestrial biomes, cont’d.

– TaigaTaiga is characterized by subarctic is characterized by subarctic coniferous forests representing coniferous forests representing minimal minimal diversity. Taiga is found south of the tundra in diversity. Taiga is found south of the tundra in North America, northern Europe and Asia.North America, northern Europe and Asia.

– DesertsDeserts support some plants and animals. support some plants and animals.

Distinguishing Between BiomesDistinguishing Between Biomes There are four major aquatic biomes that There are four major aquatic biomes that

are dependent on water type and are dependent on water type and movement.movement.– Lakes and PondsLakes and Ponds provide habitat for provide habitat for

freshwater organisms.freshwater organisms.– Streams, which vary by Streams, which vary by water temperaturewater temperature

and and water f lowwater f low ..– OceansOceans , which provide a suitable habitat for , which provide a suitable habitat for

organisms that would not survive in organisms that would not survive in freshwater.freshwater.

Distinguishing Between BiomesDistinguishing Between Biomes The Four Aquatic Biomes, cont’d.The Four Aquatic Biomes, cont’d.

– WetlandsWetlands , including swamps and marshes, , including swamps and marshes, and and estuariesestuaries (saltwater or freshwater where (saltwater or freshwater where streams flow into oceans) are lands that are streams flow into oceans) are lands that are affected by water.affected by water.

Questions?Questions?

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Understanding Ecosystems

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