Chapter 4

Ecosystems &

Communities

4.1 Climate

I. Weather & Climate

A. Weather – the day to day conditions of Earth’s atmosphere. Weather can change from day to day.

B. Climate – the average conditions in an area over a long period of time.

1. A region’s climate is defined by year-after-year

patterns of temperature and precipitation.

2. climate is rarely “uniform.”

C. microclimates – when environmental conditions vary over small distances it creates what are known as microclimates.

ex) think of how weather differs on the sides of a

mountain.

II. Factors that Affect Climate

*Global climate is shaped by many factors including:

1. solar energy trapped in the biosphere

2. latitude

3. transport of heat by winds and ocean currents

A. Greenhouse Effect

1. A balance of 3 major gases found in the atmosphere contribute to Earth’s temperature:

a) CO2 - Carbon Dioxide

b) CH4 - Methane

c) H2O – Water Vapor

2. greenhouse effect – phenomenon by which CO2, CH4, and H2O allow visible light to enter the biosphere, but also trap heat and prevent it from leaving.

a) the more greenhouse gases present, the more heat gets trapped and therefore the Earth gets warmer.

b) the greenhouse gases are all part of the nutrient cycles,

1) CO2 - carbon cycle

2) CH4 – also part of carbon cycle

3) H2O – part of water cycle

c) 30o C – how much cooler Earth would be today w/o greenhouse gases.

B. Latitude and Solar Energy

1. near the equator – solar energy is more intense, it is a direct hit of sunlight.

2. polar regions – least intense areas of solar energy.

3. tropical zones – aka tropics; located between 23.5o N and 23.5o S latitudes. Nearly direct sunlight.

4. temperate zones – 23.5o – 66.5o N & S latitudes

5. polar zones – between 66.5o – 90o N & S latitudes, least amount of direct sunlight.

*temperate & polar zones receive differing amounts of solar energy depending on the time of year.

ex) during winter, the sun is lower in the sky, therefore days are shorter and thus there is less intense solar energy.

C. Heat Transport in the Biosphere

*unequal distribution of heat across the globe creates wind and ocean currents which transport heat and moisture.

1. heat rises – warm air is less dense than cool air

2. sinking air – as air cools it sinks.

3. wind – caused by upward and downward movements of air.

4. earth’s rotation – makes wind blow from E to W.

*similar events happen in the ocean

4.2 Niches & Community Interactions

I. The Niche

A. Tolerance - the ability of an organism to withstand

fluctuations in biotic and abiotic environmental factors.

B. Range - each species can tolerate certain conditions that

other species may not be able to handle.

C. habitat - a place where an organism lives out its life. An organism can change habitats.

ex) birds fly south for winter

D. Defining the niche

Several different species may share a habitat, but the food, shelter, and other essentials of

that particular habitat may be used in differentways.

Can many different organisms live in the same habitat?Yes! Think about what lives around/ under a log:

What are some organisms that can live together under a log without fighting with each other all the time?

Millipedes, worms, insects, fungus, salamanders, can all live together in the same habitat in harmony b/c they have different “niches” or “jobs,” thus they don’t compete with each other.

D. Defining the Niche

1. Niche - the role and position that a species has in its environment. How a species meets its needs for food, shelter, how it survives, and how it reproduces. A niche is like the species “job.”

*each species is unique in satisfying all of its needs!

2. What a niche includes:

a) species interactions w/ biotic and abiotic parts of the

habitat.

b) unique strategies and structures that are important

for reducing interspecies competition.

3. It is advantageous for a species to occupy a niche that is different from the niches of other species.

ex) polar bear would NOT occupy the same niche as a grizzly bear

II. Competition

A. The Competitive Exclusion Principle - states that no 2 species can occupy exactly the same niche in the same habitat at exactly the same time.

B. Experiment w/ Paramecia

*P.aurelia vs P. caudatum

B. Dividing Resources

1. Resource Sharing – by dividing resources, competition helps determine the # and kinds of species in a community and the niche each occupies

2. Example – the spruce tree and Warblers

III. Predation, Herbivory, and Keystone Species

Some species enhance their chances of survival by having relationships with other species.

*Types of Relationships:

A. Predator - Prey - a relationship that involves a struggle for survival.

a) predator - animals which kill or eat other animals.

b) prey - the animal that gets eaten

Some famous Predator-Prey Relationships:

Predator/ Prey Interactions graphed:

*notice that as the prey line rises, so does the predator population.

*once the predator population gets too high, however, the prey line decreases.

B. Herbivore-Plant Relationships

1. Herbivory – interactions between animals and plants, in which an animal (herbivore) feeds on producers.

2. Herbivores can affect both the size and distribution of plant populations in a community and can determine the places that certain plants can survive and grow.

C. Keystone Species

1. Keystone Species – a single species that is not usually abundant in a community, yet exerts strong control on the structure of a community.

2. Keystone species can cause dramatic changes in communities.

3. The Otter example – otter eat sea urchins, which in turn feed on kelp. Otters were hunted in large amounts at one time, which resulted in almost all the kelp forests going extinct. Why???

Think: sun kelp sea urchin otter

D. Symbioses

Symbiosis - a relationship in which there is a close and

permanent association among organisms of different species.

Types of Symbiosis:

a) commensalism - a symbiotic relationship in which one species benefits and the other is neither harmed nor benefited (helped).

ex) clownfish and

sea anenome;

clownfish gets

protection, sea

anenome gets

nothing

b) Mutualism - a symbiotic relationship in which two different species benefit from each other.

Giraffes like to eat the sweet leaves of the acacia tree,thus killing the tree becausewithout leaves photosynthesiscannot happen.

Fire ants protect the treesleaves as they leave a bad taste in the giraffesmouth.

Trees get protection, ants get a home

c) Parasitism - a symbiotic relationship in which one organism benefits at the expense or harm of the other.

1) parasite - an organism which lives off of and feeds off of another organism. They usually harm, but do not kill their host. If the host dies, they will die too.

2) host - the organism off which a parasite feeds.

EX 1) Dog and tick

Recognizing ticks:

EX 2) Human and Tapeworm

• Tapeworm Facts:

• The longest tapeworm that was removed from a human came out of a woman named Sally Mae Wallace. It was removed on September 5, 1991.

• 37 feet of tapeworm was pulled out of the woman’s mouth! If you don’t believe me google her name!

• Tapeworms in whales can grow up to 120 feet long!

Tapeworm Lifecycle

Section 4.3

Succession

Succession: Change over time

*ecologists can accurately predict changes which can occur over time

* Ecological succession - the orderly, natural changes and replacement of species that happens in communities of the ecosystem. Succession occurs in stages and is often difficult to observe b/c it can take decades to happen.

A. Primary Succession

- Primary succession - the colonization of NEW sites by communities of organisms.

Primary Succession (continued)

1. Occurs in areas where life had never been present before

2. Pioneer species - the first species to move in and

colonize an area; act as a building block or foundation

for other new species. In primary succession the

pioneer species are Lichens.

3. Recycling of pioneer species - when pioneer species die, their dead, decaying bodies are used as fertilizer to initiate the emergence of other species into the area. The lichens break down rock into soil, then when they die they fertilize the soil, thus allowing grasses and small plants to grow, which in turn will attract animals.

5. Time - it takes many, many years, even decades for primary succession to reach its climax community.

Primary succession starts with rock and lichens.

It takes a very long time to reach the climax community.

B. Secondary Succession

1. Secondary succession - refers to the sequence of community changes that takes place after a community is disrupted by natural disasters or human actions.

Causes a gradual change in the community of

organisms living in the area.

It differs from primary succession because it occurs in

areas which have already contained life and already

have soil.

Secondary Succession (continued)

2. Pioneer species - differ from those in primary, NOT

lichens; usually grasses and small plants are the

pioneer species in secondary succession.

3. Climax community - may turn out to be identical to that

of primary succession; takes less time to reach climax community in secondary than in primary b/c soil is

already present.

4. Examples -

floods, fire

Yellowstone

Secondary succession – notice there are already plants, not starting from rock and lichens.

C. Climax Community

1. Climax Community – a stable, mature community that undergoes little or no change in species; when a community reaches the point where one does not notice any more change taking place in the ecosystem. Some communities are disturbed so often they never reach stability.

2. Primary vs. Secondary Succession – Secondary succession will reach climax community quicker than primary since secondary usually results from a human or natural disturbance, and thus already has soil present.

Primary vs. Secondary Succession

4.4 Biomes

I. The Major Biomes

*What Abiotic and Biotic Factors characterize Biomes?

A. Regional Climates

1. Climates can differ at the same latitude depending on:

a) Proximity to bodies of water

b) proximity to mountain ranges

2. different climate – different plant and animal communities.

B. Defining Biomes

*ecologists classify Earth’s terrestrial ecosystems into 10 different biomes.

1. Biomes – are described in terms of abiotic and biotic factors:

a) climate

b) soil type

c) plant life

d) animal life

2. Each biome is associated w/ seasonal patterns of temperature and precipitation that can be summarized in a climate diagram.

3. Organisms within each biome can be characterized by:

a) adaptations that enable them to live

b) adaptations that allow for successful for reproduction

C. Major Biomes (http://www.blueplanetbiomes.org/)

1. Tropical Rain Forest

*located around the equator

a) abiotic factors

1) temperature/climate – hot and wet all year round;

About 2 m of rain a year

2) soil – poor in nutrients b/c it is waterlogged

- much erosion; organic matter is used quickly

b) Biotic factors

1) Plant life

a) contain large leaves to help in attaining sunlight

b) trees contain “buttress roots”

for support

c) Epiphytes – plants that grow

on other plants and utilize

them for nutrients.

d) examples – palms, banana trees, vines, ferns, orchids, moss

2. animal life

a) many use camouflage to hide from predators

b) adaptations – for climbing, jumping, and flight

c) examples - ants, termites, fungi, decomposers, sloths, beetles, birds, gorillas, orangutan, snakes,

frogs, butterflies, etc.

C. Special Features

1) canopy – formed by tops

of tall trees that are about

50-80 meters off the ground.

2) understory – shaded region

located below the canopy

where shorter trees and

vines grow.

2. Tropical Dry Forest

*grow in areas where rainy seasons

alternate with dry seasons;

fluctuations between rain and drought

a) Abiotic factors

1) temperature/ climate – warm all year round

2) soil – rich, but subject to erosion during rainy season

b) Biotic factors

1) plant life

a) deciduous – seasonal loss of leaves to survive

periods of drought.

b) adaptations – waxy layers on some plant

leaves to reduce transpiration.

c) examples – acacias, succulents such as agave

and aloe.

2) animal life

a) estivation – “hibernation” during dry seasons

b) migration – some animals move during dry seasons

c) examples – leopard, tigers, buffalo, jackal, ocelot,

duikers, foxes, bats, lemurs, kangaroos,

possums, wallabies, rabbits, monkeys

3. Tropical Grassland/ Savanna/ Shrubland

*receives less seasonal rainfall than tropical dry forests, but more than deserts.

a) Abiotic factors

1) temperature/climate – warm, seasonal rain;

sometimes fires occur from lightning

2) soil – compact soils;

somewhat fertile.

b) Biotic factors

1) plant life

a) grassy areas with isolated trees and shrubs

b) adaptations – waxy covers to prevent water

loss

c) examples – eucalyptus,

elephant grass,

kangaroo paw,

whistling thorn

2) animal life

a) grazers – elephants, rhinos, other large herbivores

b) migrate during dry season to find water

c) examples – elephants, rhinos,

baboon, emu, zebra, koala,

lions, mongoose

4. Desert

*less than 25 cm of precipitation a year

a) Abiotic factors

1) temperature/ climate – low precipitation;

varies depending on elevation and latitude

2) soil – rich in minerals, but poor in organic material

b) Biotic factors

1) plant life

a) adaptations for dry seasons:

1) water storage in plant tissues

2) waxy coverings

3) special types of photosynthesis

b) examples – cacti, joshua tree

2) animal life

a) nocturnal – active at night because of it being too hot

during the day

b) many animals get water from the foods they eat

c) examples – armadillo, various lizards, gila monster,

bobcat, cactus wren, coyote, kangaroo rat, owls,

thorny devil, numerous insects such as scorpions and

spiders

5. Temperate Grassland

*plains, prairies, pampas, steppes

*today most of these areas have been turned into farmland b/c they are so fertile

*occasional fires due to dry climate

a) Abiotic factors

1) temperature/climate – warm to hot summers, cold

winters, moderate precipitation.

2) soil – fertile; underlayer of humus

b) Biotic factors

1) plant life

a) most plants are resistant to grazing and fire

b) have root structures that help to maintain fertile soil

c) examples – buffalo grass, fleabane, milkweed,

stinging nettle, various grasses

2) Animal life

a) adaptations – b/c of open land small animals make use of

camouflage and burrowing to avoid predators.

b) examples – bald eagle, badger, coyote, foxes,

bumblebee, prairie dog

6. Temperate Woodland and Shrubland

*Chapparal

*fire is a constant threat b/c of dryness

a) abiotic factors

1) temperature/ climate – hot, dry, summers, moist

winters

2) soil – thin, nutrient poor

b) Biotic factors

1) plant life

a) adaptations - to drought like conditions, waxy covers

and fire resistant

b) examples – blue oak, manzanita, olive tree,

torrey pine, sage brush, fairy duster, french broom

2) Animal life

a) tend to be “browsers” – eat varied grasses, leaves, and

shrubs

b) camouflage is important in open areas

c) examples – jackrabbit, foxes, puma, spotted skunk,

wild goat, aardwolf

L

7. Temperate Forest

*deciduous forests

a) Abiotic factors

1) temperature/ climate – seasonal, cold to moderate

winters, warm summers

2) Soil – fertile, rich in humus

*humus – formed from decaying

leaves and other organic material

b) Biotic factors

1) plant life

a) deciduous trees lose leaves and go dormant during

the winter season

b) conifers have needles and waxy covers to reduce

water loss in winter

c) examples – hickory, maple, sassafras, tulip trees,

junipers, firs, birch, oak, beech

2. Animal life

a) organisms make use of camouflage to avoid predators

b) browsers – eat a varied diet

c) examples – squirrel, rabbit, deer, black bear, bald eagle,

chipmunk, weasel

8. Northwest Coniferous Forest

*b/c of lush vegetation these forests are also known as “temperate rain forests” or “alpine areas”

a) Abiotic factors

1) temperature/ climate – mild; abundant precipitation in

fall, winter, and spring; cool dry summer.

2) soil – rocky and acidic due to conifers

b) Biotic factors

1) plant life

a) lush, dense, plant growth

b) among the tallest trees in the world

c) examples – giant redwoods, spruce,

firs, hemlocks, flowering trees like rhododendron and

dogwood

2) Animal life

a) camouflage – used to avoid predation

b) browsers – eat a varied diet

c) examples – yak, snow leopard, mountain goat, llama, chinchilla, condor

9. Boreal Forest

*Aka – taiga – “northern coniferous forests”

*located mainly in northern parts of the N. Hemisphere

a) Abiotic factors

1) temperature/climate –

long cold winters, short mild

summers; high humidity and

moderate precipitation

2) soil – acidic and nutrient poor due to numerous conifers.

b) Biotic factors

1) plant life

a) conifers – adapted to winter, needles shed snow and

prevent water loss

b) Dark greens absorb heat energy

c) Examples – balsam fir, black spruce, douglas fir, various pines and cedars.

2) Animal life

a) staying warm is a challenge – animals have small

extremities to reduce heat loss and have extra insulation

b) migration – animals migrate to warmer climate during

winter months

c) examples – black bear, bald eagle, lynx, snowshoe hare,

grizzly, gray wolf, wolverine, lemmings, reindeer, moose

Don’t be a Lemming……..

10. Tundra

*contains permafrost – a layer of permanently frozen subsoil

*Treeless

a) Abiotic factors

1) temperature/climate - strong winds, low precipitation;

short soggy summers and long, cool, dark

winters

2) Soil

1) nutrient poor due to permafrost

2) only 1st few centimeters thaw during the summer

3) treeless due to permafrost

b) Biotic factors

1) plant life

a) low growing plants w/ shallow roots due to shallow

soil

b) seeds dispersed by wind

c) nitrogen fixing bacteria – on roots of plants to cope

cope with lack of nitrogen in soil

d) examples – arctic mosses, arctic willow, bearberry,

pasque flower

2) Animal life

a) migration – animals migrate during harsh winter

b) adaptations

1) some have “natural antifreeze”

2) small extremities to limit heat loss

3) varied diet

c) examples – arctic fox, caribou, ermine, grizzly, musk ox,

harlequin duck, polar bear, snowy owl, many animals

migrate between the taiga and tundra.

D. Other Land Areas

*not neatly classified into biomes

1. Mountain Ranges

a) location – found on all biomes

b) conditions vary depending on:

1) elevation

2) precipitation

3) wind

4) soil type

5) temperature

c) plants – become more sparse as you go higher up the

mountain

d) Treeline – area where trees can

no longer grow

e) Temperature – gets cooler the

higher up the mountain you go

2. Polar Ice Caps

a) location – borders the tundra

b) temperature/climate – cold

year round

c) plants – few plants with the exception of some algae,

moss and lichens

d) Animals – marine mammals, penguins, seals, polar bear,

insects, mites

e) Example – Antarctica, covered by 5 KM of ice

Section 4.5

Aquatic Ecosystems

*75 % of our planet is aquatic

I. Conditions Underwater

*Aquatic organisms are affected by:

1) water depth

2) temperature

3) flow

4) amount of dissolved nutrients

A. Water Depth

*water depth is critical b/c it determines how much sunlight can penetrate through the water

1. photic zone – sunlit region near the surface where photosynthesis can occur; can range from 200 meters to only a few meters deep.

*phytoplankton and zooplankton are found in abundance

in the photic zone

2. aphotic zone – beneath the photic zone where light can no longer penetrate.

*no light = no photosynthesis

*”sea creatures”

3. Benthic zone – aquatic floor; rock and sediment on the bottom of lakes, streams, and oceans.

a) benthos – organisms that live in the benthic zone

b) if shallow enough it can be photic

B. Temperature & Climate

1. warmer near equator; cooler towards poles

2. temperature varies with depth

3. currents impact water temperature

C. Nutrient Availability

1. oxygen, nitrogen, potassium, and phosphorus vary within and between bodies of water

2. salinity – the amount of salt in the ocean

II. Freshwater Ecosystems

*3% of earths’ surface water is fresh water

*freshwater ecosystems are divided into 3 main categories:

1) rivers and streams

2) lakes and ponds

3) freshwater wetlands

A. Rivers and Streams

1. Often originate from underground water sources in mountains and hills

2. source – the source of the river has plenty of O2, but little plant life

3. downstream – sediments build up and plants become more abundant

B. Lakes and Ponds

1. Food Webs – based on combination of plankton and attached algae and plants.

2. Plankton – refers to both phytoplankton and zooplankton

3. Water flow and circulation – water flows in and out lakes and ponds via groundwater and circulates between the surface and the benthos, which distributes heat and nutrients.

C. Freshwater Wetlands

1. Wetland – an ecosystem in which water either covers the soil or is present at or near the surface for at least part of the year.

2. Nutrient rich and highly productive

3. Breeding grounds for many organisms

4. Important environmental functions:

a) purify water by filtering pollutants

b) prevent flooding by absorbing large amounts of water and

slowly releasing it

5. 3 main types:

a) freshwater bogs

b) freshwater marshes

c) freshwater swamps

Freshwater bog Freshwater marsh

Freshwater swamp

III. Estuaries

*estuary – special kind of wetland formed where a river meets the sea.

A. Contain a mix of freshwater and saltwater

*salinity – is based on the rise and fall of ocean tides as well as flooding and drought situations.

1) the higher the tide, the saltier the estuary

2) the lower the tide, the lower the salinity

B. Photic

*many estuaries are shallow enough to be photic the entire way through

C. Biomass

1. support an astonishing amount of biomass

2. spawning and nursery grounds for many fish and shellfish

D. Saltmarsh – temperate estuaries characterized by salt tolerant grasses.

ex) Chesapeake Bay, Md.

E. Tropical Estuaries

*Mangroves – many salt tolerant trees

ex) Florida’s Everglades National Park

IV. Marine Ecosystems

*ocean is divided into zones based on depth and distance to shore:

1) intertidal zone

2) coastal ocean

3) open ocean

A. Intertidal Zone

*between the tides”

1. Organisms are often submerged at high tide and

exposed to air and sunlight at low tide.

2. Subject to regular and extreme changes in temp.

3. Battered by waves and currents

4. Types of organisms:

a) “suction cup” organisms

ex) snails, sea stars

b) “glue” organisms

ex) mussels, barnacles

c) “burrowing” organisms

ex) clams, worms, crabs

B. Coastal Ocean

1. Extends from the low tide mark to the outer edge of the continental shelf.

2. Continental shelf – shallow border that surrounds the continents.

3. Highly productive region:

a) brightly lit

b) nutrient rich from run off from land

4. Costal communities:

a) Kelp forests

b) Coral reefs

Kelp Forest Coral Reef

C. Open Ocean

1. Begins at the edge of the continental shelf and extends outward.

2. Approximately 90% of the worlds ocean is considered “open.”

3. Depth – 500 meters 10,000 meters

4. 2 main zones:

a) open ocean photic zone

b) open ocean aphotic zone

a) Open ocean photic zone

1) low nutrient levels

2) main photosynthetic organisms are phytoplankton

*most photosynthesis on earth happens here

b) Open ocean aphotic zone

*deepest parts of the ocean

1) food webs are based on:

a) dead organisms from

photic zone

b) chemosynthetic organisms

2) Special adaptations

-no photosynthesis; no light, cannot

make food

-special adaptations

ex) large eyes, or no eyes at all

bioluminescence