Community DistributionCommunity Distribution

Homeostasis in Homeostasis in CommunitiesCommunities

Changing with the EnvironmentChanging with the Environment Ecosystems are always changing.Ecosystems are always changing. Changing conditions affect Changing conditions affect

communities.communities. There are patterns to these There are patterns to these

changes that helps us understand changes that helps us understand how ecosystems developed.how ecosystems developed.

Limiting factorsLimiting factors

Limiting factorsLimiting factors: any biotic or abiotic : any biotic or abiotic factor that restricts the existence, factor that restricts the existence, numbers, reproduction, or distribution numbers, reproduction, or distribution of organisms.of organisms.

Remember that effects on one Remember that effects on one population have indirect effects on population have indirect effects on other populations within the other populations within the community.community.

Ranges of toleranceRanges of tolerance

ToleranceTolerance: the ability to withstand : the ability to withstand fluctuations in biotic and abiotic fluctuations in biotic and abiotic environmental factors.environmental factors.

Some species can tolerate conditions Some species can tolerate conditions that other species cannot.that other species cannot.

Seccession: A Change in Seccession: A Change in Communities over TimeCommunities over Time

SeccessionSeccession: orderly, natural : orderly, natural changes that take place in the changes that take place in the community of an ecosystem.community of an ecosystem.

Primary SuccessionPrimary Succession: the : the colonization of new sites by colonization of new sites by communities of organismscommunities of organisms

E.g. lava forming new land, silt creating E.g. lava forming new land, silt creating new soilnew soil

Pioneer plants create soilPioneer plants create soil Pioneer plants die and decay adding their Pioneer plants die and decay adding their

nutrients to the raw environment and lay nutrients to the raw environment and lay the foundation for soil.the foundation for soil.

Once soil is present it is possible for Once soil is present it is possible for small weedy plants, ferns and insects to small weedy plants, ferns and insects to move in. More plants die and add to the move in. More plants die and add to the increasing amount of soil.increasing amount of soil.

Eventually a climax community is Eventually a climax community is achieved.achieved.

Climax communityClimax community Climax communityClimax community: a stable mature : a stable mature

community that undergoes little or no community that undergoes little or no succession. succession.

The climax community represents the The climax community represents the combination of plants and animals which combination of plants and animals which make the most efficient use of available make the most efficient use of available resources and conditions. In other words, resources and conditions. In other words, the community established by nature is the community established by nature is the one which works best given the the one which works best given the climate, topography and other climate, topography and other characteristics of the area. characteristics of the area.

Temperate Broadleaf Temperate Broadleaf Deciduous Forest Deciduous Forest

Secondary successionSecondary succession Secondary successionSecondary succession: the sequence : the sequence

of community changes that takes of community changes that takes place when a community is disrupted place when a community is disrupted by natural disasters or human by natural disasters or human actions.actions.

Since the soil is already in place, Since the soil is already in place, secondary succession can take place secondary succession can take place five to ten times faster than primary five to ten times faster than primary succession.succession.

Secondary seccession (cont)Secondary seccession (cont)

When a community is significantly disturbed, When a community is significantly disturbed, the loss of the vegetation may change the the loss of the vegetation may change the abiotic conditions. If this occurs and the habitat abiotic conditions. If this occurs and the habitat has changed, secondary succession may lead has changed, secondary succession may lead to a different climax community. to a different climax community.

An An example is the tropical rain forestexample is the tropical rain forest. The . The forest "creates" the rainfall through the process forest "creates" the rainfall through the process of of transpirationtranspiration. When the trees are removed, . When the trees are removed, the rainfall stops. The land then becomes arid. the rainfall stops. The land then becomes arid. The resulting new climax community is often The resulting new climax community is often desert shrubs desert shrubs

Example of human interference with Example of human interference with succession-succession-

1. Producing a lawn means a constant battle against 1. Producing a lawn means a constant battle against natural natural 2. What you must do to maintain such a system 2. What you must do to maintain such a system a. a. plant grass seed-plant grass seed- competition against natural seed competition against natural seed

dispersal dispersal b. b. mowmow- limits the establishment of trees and other tall species - limits the establishment of trees and other tall species

c. c. apply herbicides-apply herbicides- to eliminate interspecific competition and to eliminate interspecific competition and to cut down on species diversity- to cut down on species diversity-

d. d. apply fertilizer-apply fertilizer- grass species use up soil nutrients quickly grass species use up soil nutrients quickly e.e. irrigate- irrigate- natural rainfall is often inadequate for lawn grass natural rainfall is often inadequate for lawn grass f. f. apply fungicidesapply fungicides and other chemicals to control disease and other chemicals to control disease and insect pests- must be done because an unnatural and insect pests- must be done because an unnatural ecosystem is more prone to disruptionecosystem is more prone to disruption

3. Thus, when humans interfere with plant communities 3. Thus, when humans interfere with plant communities -> many problems that would be controlled in a natural -> many problems that would be controlled in a natural system (this same thing happens in farming) system (this same thing happens in farming) 4. Without the continued interference of humans, the 4. Without the continued interference of humans, the yard would have a natural sequence of succession yard would have a natural sequence of succession over timeover time

Example: secondary succession on Example: secondary succession on abandoned farm in Marylandabandoned farm in Maryland

1. Annuals (weeds like crabgrass) 1-2 years 1. Annuals (weeds like crabgrass) 1-2 years 2. 2. PerennialsPerennials (herbs and tall grasses) 2-5 (herbs and tall grasses) 2-5 years years

3. Young pine seedlings in tall grass 5-10 3. Young pine seedlings in tall grass 5-10 years years 4. 4. Pine forestPine forest 10-150 years 10-150 years

5. 5. Deciduous hardwood forestDeciduous hardwood forest (climax) 150+ (climax) 150+ years years

Temperate Broadleaf Temperate Broadleaf Deciduous Forest Deciduous Forest

BiomesBiomes

Aquatic Biomes: Life in the WaterAquatic Biomes: Life in the Water

BiomeBiome: a large group of ecosystems : a large group of ecosystems that share the same type of climax that share the same type of climax community.community.

75% of earth’s surface is covered 75% of earth’s surface is covered with water.with water.

Most are marine.Most are marine. Fresh water is confined to rivers, Fresh water is confined to rivers,

streams, ponds, and most lakes.streams, ponds, and most lakes.

2 Main Types of Aquatic 2 Main Types of Aquatic BiomesBiomes

MarineMarine

FreshwaterFreshwater

Marine BiomesMarine Biomes

Life began in the Life began in the ocean billions of years ocean billions of years ago.  Most of the life ago.  Most of the life forms which currently forms which currently occupy the earth had occupy the earth had their start as single-their start as single-celled organisms, celled organisms, forced into evolution forced into evolution by an ever-changing by an ever-changing environment. environment. 

Ecologist often separate Ecologist often separate marine biomes marine biomes

Shallow, sunlit zones called Shallow, sunlit zones called the the photic zone. photic zone. They exist They exist along coast lines (coastal along coast lines (coastal ecosystems).ecosystems).

Unlighted zones: Unlighted zones: aphotic aphotic zonezone

Another way to divideAnother way to divide

The marine regions can also be divided The marine regions can also be divided into into

coral reefscoral reefs

EstuariesEstuaries

oceansoceans

Coral ReefsCoral Reefs In the warm shallow waters In the warm shallow waters

which line the continents and which line the continents and surrounding islands lie surrounding islands lie barriers called barriers called coral reefscoral reefs. .

Coral is a living organism Coral is a living organism consisting of animal and consisting of animal and algae tissues.   The coral reef algae tissues.   The coral reef is also host to other species is also host to other species such as starfish, octopi, and such as starfish, octopi, and other mollusks. other mollusks.

EstuariesEstuaries EstuaryEstuary: A costal : A costal

body of water partially body of water partially surrounded by land in surrounded by land in which fresh water and which fresh water and salt water mix.salt water mix. Salinity in the estuary Salinity in the estuary

changes with the tide changes with the tide

and contain salt marsh and contain salt marsh

ecosystemsecosystems..

Intertidal ZoneIntertidal Zone

The portion of the The portion of the shoreline that lies shoreline that lies between high and low between high and low tide lines is called the tide lines is called the intertidal zoneintertidal zone..

Coasts Coasts

    Because of rising and Because of rising and falling tides, coastal areas falling tides, coastal areas are constantly changing, are constantly changing, with various animals and with various animals and marine plants living at the marine plants living at the bottom, and on the bottom, and on the seashore.  seashore. 

Rocky coastal areas are Rocky coastal areas are host to fewer species.host to fewer species.

OceanOcean The Pelagic zoneThe Pelagic zone:: Out in the open Out in the open

ocean (photic)ocean (photic) host to many species of fish and marine host to many species of fish and marine

mammals, plankton ,and some floating mammals, plankton ,and some floating seaweed. is called sargasum.seaweed. is called sargasum.

The Benthic zoneThe Benthic zone: deep-sea (aphotic: deep-sea (aphotic host to silt, sand, and slowly decomposing host to silt, sand, and slowly decomposing

organisms.  This area is very cold because of its organisms.  This area is very cold because of its depth. There are few plants at this level, and the depth. There are few plants at this level, and the animals include mostly bottom feeding organisms animals include mostly bottom feeding organisms such as starfish, anemones, sponges, amongst such as starfish, anemones, sponges, amongst others, as well as various micro-organisms. others, as well as various micro-organisms.

Oceans cont.Oceans cont. Abyssal zone: tAbyssal zone: the deepest part of the he deepest part of the

ocean ocean host to many species of invertebrates and host to many species of invertebrates and

fish including such oddities as the fish including such oddities as the coelacanthcoelacanth, a prehistoric fish once thought , a prehistoric fish once thought extinct, and other fish that extinct, and other fish that bioluminescencebioluminescence.  . 

The abyssal zone is very cold, and highly The abyssal zone is very cold, and highly pressurized.  Its floor features pressurized.  Its floor features thermal thermal ventsvents formed by spreading tectonic plates formed by spreading tectonic plates which release hydrogen sulfide (Hwhich release hydrogen sulfide (H22S) and S) and other minerals which are consumed by other minerals which are consumed by bacteria that form the bottom of the food bacteria that form the bottom of the food web.web.

Terrestrial Biomes Terrestrial Biomes Include:Include:

1.1. The TundraThe Tundra

2.2. Taiga (coniferous forests)Taiga (coniferous forests)

3.3. The Temperate ForestsThe Temperate Forests

4.4. DesertsDeserts

5.5. GrasslandsGrasslands

The TundraThe Tundra

There are 2 types of There are 2 types of TundraTundra1.1.Arctic tundraArctic tundra

2.2.Alpine tundraAlpine tundra

Arctic tundraArctic tundra PermafrostPermafrost: a layer of frozen ground, : a layer of frozen ground,

found under the thin layer of top soil, found under the thin layer of top soil, which never thaws.which never thaws.

The soil in the tundra is lacking in The soil in the tundra is lacking in nutrients because low temperatures slow nutrients because low temperatures slow the decay process.the decay process.

Short growing season.Short growing season. Long days during the “summer” and long Long days during the “summer” and long

nights during the “winter”.nights during the “winter”. Mosquitoes are the most common tundra Mosquitoes are the most common tundra

animal.animal.

Alpine TundraAlpine Tundra The alpine tundra The alpine tundra

biome exists on rocky biome exists on rocky mountaintops. Because mountaintops. Because trees cannot grow at trees cannot grow at this high altitude, most this high altitude, most of the alpine tundra of the alpine tundra plant life consists of plant life consists of shrubbery and small shrubbery and small leafy plants leafy plants

Animals include bighorn Animals include bighorn sheep, mountain goats, sheep, mountain goats, elk, pika, marmots, and elk, pika, marmots, and birds such as the white-birds such as the white-tailed parmigan and the tailed parmigan and the grouse.grouse.

Taiga (northern Taiga (northern coniferous forest)coniferous forest)

Lies just south of the tundra.Lies just south of the tundra. Still harsh but although often are warmer Still harsh but although often are warmer

and wetter than the tundra.and wetter than the tundra. Permafrost is usually absentPermafrost is usually absent Conifer needles make the soil acidic and Conifer needles make the soil acidic and

poor in minerals.poor in minerals. More large species (moose, deer, lynx, More large species (moose, deer, lynx,

wolves)wolves)

Coniferous forestConiferous forest

DesertDesert South of the taiga.South of the taiga. AridArid Sparse to nonexistent Sparse to nonexistent

plant life.plant life. Plant include cacti, Plant include cacti,

tumble weeds.tumble weeds. Animals are small and Animals are small and

nocturnal. The burrow nocturnal. The burrow during the day to reduce during the day to reduce water needs.water needs.

GrasslandsGrasslands

Include:Include:PrairiesPrairiesSteppeSteppeSavannaSavanna

Prairies Prairies

Large communities covered with grasses and Large communities covered with grasses and similar small plants.similar small plants.

Climate where dry seasons occur so cannot Climate where dry seasons occur so cannot support forests.support forests.

Rich soil due to yearly die-off of grasses.Rich soil due to yearly die-off of grasses. Animals include large herbivores such as Animals include large herbivores such as

deer and bison. Predators include the wolf, deer and bison. Predators include the wolf, coyote, and fox. Small animals like the rabbit, coyote, and fox. Small animals like the rabbit, praire dog, and chipmunk (pocket gopher).praire dog, and chipmunk (pocket gopher).

SteppeSteppe

The Steppe biome is a The Steppe biome is a dry, cold, grassland that is dry, cold, grassland that is found in all of the found in all of the continents except continents except Australia and Antarctica. It Australia and Antarctica. It is mostly found in the is mostly found in the USA, Mongolia, Siberia, USA, Mongolia, Siberia, Tibet and China. Tibet and China.

Steppe cont.Steppe cont.

The Steppe biome is usually found The Steppe biome is usually found between deserts and forests. If it got between deserts and forests. If it got more rain, it would become a forest. If it more rain, it would become a forest. If it got less rain, it would become a desert. got less rain, it would become a desert. The average rainfall is 10-30 inches per The average rainfall is 10-30 inches per year, with 4-5 being received in the year, with 4-5 being received in the spring.spring.

SavannaSavanna

A savanna is a rolling A savanna is a rolling grassland scattered with grassland scattered with shrubs and isolated trees, shrubs and isolated trees, which can be found between which can be found between a tropical rainforest and a tropical rainforest and desert biome. Not enough desert biome. Not enough rain falls on a savanna to rain falls on a savanna to support forests. Savannas support forests. Savannas are also known as tropical are also known as tropical grasslands. They are found grasslands. They are found in a wide band on either side in a wide band on either side of the equator on the edges of the equator on the edges of tropical rainforests.of tropical rainforests.

Temperate ForestsTemperate Forests

Forest BiomesForest Biomes Represent the largest and most Represent the largest and most

ecologically complex systems.  ecologically complex systems.  They contain a wide assortment They contain a wide assortment

of trees, plants, mammals, of trees, plants, mammals, reptiles, amphibians, reptiles, amphibians, invertebrates, insects and micro-invertebrates, insects and micro-organisms which vary depending organisms which vary depending on the zone's climates.on the zone's climates.  

2 Types of temperate 2 Types of temperate forestsforests

Deciduous forests Deciduous forests

Rain forestsRain forests

Temperate Deciduous Temperate Deciduous ForestForest

Are a close relative of the Taiga biome, and can be Are a close relative of the Taiga biome, and can be found in areas with a milder, shorter winter season. found in areas with a milder, shorter winter season.

Trees in the temperate forest include evergreens, Trees in the temperate forest include evergreens, maple, elm, oak, cedar and other trees which shed maple, elm, oak, cedar and other trees which shed their leaves in the fall.  their leaves in the fall. 

The temperate forest's soil in richer than that of the The temperate forest's soil in richer than that of the coniferous forestsconiferous forests

The forests' canopy is thinner, allowing more light and The forests' canopy is thinner, allowing more light and heat to penetrate, permitting photosynthesis in the heat to penetrate, permitting photosynthesis in the forest floor plantsforest floor plants

Animals include cold blooded such as garter snakes, Animals include cold blooded such as garter snakes, turtles, and a few amphibians as well as a variety of turtles, and a few amphibians as well as a variety of warm blooded animals.warm blooded animals.

Many species hibernate, and/or burrow in the ground to Many species hibernate, and/or burrow in the ground to pass the winter months. pass the winter months.

RainforestsRainforests

2 Types2 TypesTemperate Temperate

Rain ForestsRain Forests

Tropical Rain Tropical Rain ForestsForests

Temperate Rain ForestTemperate Rain Forest

Borders oceans and found on Borders oceans and found on western edge of North and South America

moist air from the Pacific Ocean drops between 60 and 200 inches of rain a year

 

Temperate Rain Forest cont.Temperate Rain Forest cont. The temperate rain forest has seasonal

variation, with summer temperatures rising to about 80 ˚F and winter temperatures dropping to near freezing. In the northernmost regions, winter may be cold enough for some ice and snow.

Although this rain forest has layers of tall, medium, and low growing vegetation, the cool winters limit the numbers and kinds of life forms that live here. Compared to the tropical rain forest, the temperate rain forest has a less complex ecology.

Tropical Rain ForestTropical Rain Forest

Found along the Found along the equatorequator

Receives as much as Receives as much as 400 cm of rain a year 400 cm of rain a year with an average temp. with an average temp. of 25of 25˚C˚C

As a climax comm. As a climax comm. The forest floor is bare The forest floor is bare due to thick canopy.due to thick canopy.

Thick canopy full of Thick canopy full of diverse life.diverse life.