CHAPTER 4ECOSYSTEMS AND COMMUNITIES

Weather includes the daily conditions of Earth’s atmosphere at a particular time and place

Weather includes temperature and precipitation Climate involves the average, year after year

conditions of temperature and precipitation in a particular region

Climate is caused by the trapping of heat by the atmosphere, latitude, the transport of heat by wind and ocean currents, and the amount of precipitation that results

4-1: THE ROLE OF CLIMATE

1. solar energy2. presence of certain gases in the

atmosphere

WHAT AFFECTS TEMPERATURE?

The natural insulating blanket of the biosphere=atmosphere

Carbon dioxide, methane, water vapor, and a few other atmospheric gases trap heat energy and maintain Earth’s temperature range

THE GREENHOUSE EFFECT

1. Greenhouse gases allow solar energy to penetrate the atmosphere in the form of sunlight

2. Most sunlight hits the surface of our planet and is converted into heat energy and radiated back into the atmosphere

3. Heat energy is not allowed to pass out of the atmosphere as readily as light energy enters it

4. The greenhouse gases trap heat inside the earth’s atmosphere

GREENHOUSE EFFECT CONT.

Earth is a sphere tilted on its axis, so solar radiation strikes different parts of Earth’s surface at an angle which varies throughout the year

0 degrees latitude=equator=sun is directly overhead at noon all yearmore heat

90 degrees latitude=north and south poles=sun is lower in the sky for months at a timeless heat

The difference in heat distribution with latitude has important effects on Earth’s climate zones

THE EFFECT OF LATITUDE ON CLIMATE

1. Polar zones: cold areas where sun’s rays strike Earth at low angles. Located in areas at the North and South poles, between 66.5 degrees and 90 degrees N and S latitude

2. Temperate zones: between the polar zones and tropics; climate ranges from hot to cold, depending on the season

3. Tropical zone (Tropics): near the equator between 23.5 degrees N and S latitude. The tropics receive direct or nearly direct sunlight all year, making the climate almost always warm

THREE MAIN CLIMATE ZONES

Unequal heating of Earth’s surface drives winds and ocean currents, which transport heat throughout the biosphere

Winds form because the warm air rises and cool air sinks. Air at the equator rises at the same time, cool air from the poles sinks. The upward movement of warm air and downward movement of cool air creates air currents (wind) that move heat through the atmosphere from regions of sinking air to regions of rising air

Prevailing winds bring warm or cold air to a region

HEAT TRANSPORT IN THE BIOSPHERE

Similar patterns of heating and cooling occur in oceans Ocean currents transport heat energy within the

biosphere; the surface ocean currents warm or cool the air above them, which affects weather and climate of the land masses

Mountains cause moist air masses to rise, clouds form and precipitation begins on the mountains. Once the air mass reaches the far side of the mountain, it has lost moisture=this is called a rain shadow. Read chapter 4 section 1 in your book and complete

chapter 4 section 1 guided reading worksheets!!!!

HEAT TRANSPORT CONTINUED

Biotic factors are living things within an ecosystem.

Examples: trees, birds, plants, bacteria Abiotic factors are physical, non-living

factors that affect an ecosystem Examples: temperature, precipitation

***Together, biotic and abiotic factors determine the survival and growth of an

organism and the productivity of the ecosystem in which the organism lives.

4-2: WHAT SHAPES AN ECOSYSTEM?

Habitats are areas where organisms live A niche is the full range of physical and

biological conditions in which an organism lives and the way in which the organism uses those conditions

Example: the type of food the organism eats, how it obtains this food, and which other species use the organism as food

SHAPING AN ECOSYSTEM CONTINUED

Competition, predation, and various forms of symbiosis can powerfully affect an ecosystem

Competition occurs when organisms of the same or different species attempts to use an ecological resource in the same place at the same time

Resources are necessities for life. Examples include water, nutrients, light, food and space

COMMUNITY INTERACTIONS

Competitive exclusion principle: no two species can occupy the same niche in the same habitat at the same time

Direct competition in nature results in a winner and a loser, where the losing organism fails to survive

Predation: when one organism captures and feeds on another organism

Predator: organism that does the killing Prey: organism that becomes the food

Symbiosis: any relationship in which two species live closely together

SYMBIOSIS

1. Mutualism: both species benefit from the relationship. Example: flowers provide insects with food and insects help flowers reproduce by pollinating them

2. Commensalism: one member in the relationship benefits and the other isn’t affected. Example: barnacles attach themselves to whales. The barnacles benefit from the constant movement of water as it carries food particles to them. The whales are not helped nor harmed.

THREE TYPES OF SYMBIOSIS

3. Parasitism: one organism lives on or inside another organism and harms it. Example: tapeworms are parasites that live in the intestines of mammals (host). The parasite obtains all or part of its nutritional needs; they weaken the host but rarely kill them

Ecosystems and communities are always changing in response to natural and human disturbances.

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

This process is called ecological succession.

ECOLOGICAL SUCCESSION

Primary succession: succession on land surfaces where no soil exists. Example: occurs on surfaces formed from volcanic eruptions that have built new islands

1. No soil: just ashes and rock2. Pioneer species: first species to populate the

area (ex. Lichens, fungi and algae on rock)3. When pioneer species (lichens) grow, the rock

breaks apart4. Lichens die and add organic material to help

form soil

SUCCESSION

Secondary succession occurs when land cleared and plowed for farming is abandoned.

Secondary succession also occurs after wildfires burn woodlands

Climax species: mature, stable species that don’t undergo further succession

SECONDARY SUCCESSION

1. A whale dies and sinks to the barren ocean floor; the carcass attracts scavengers and decomposers that feast on decaying meat (ex. Sharks)

2. Within a year, most tissue has been eaten and the carcass supports a smaller number of fish, crabs, snails; the decomposition of the whale enriches sediment with nutrients where marine worms begin to live

3. When the skeleton remains, heterotrophic bacteria decompose the oils inside the whale bones which release compounds that serve as energy sources for chemosynthetic autotrophs (ex. Mussels, worms, crabs, clams)

***re-read section 4-2 pages 90-97 in your book and complete the guided reading worksheets***

SUCCESSION IN MARINE ECOSYSTEMS

A biome is a physical environment that contains characteristic assembly of plants and animals

The major biomes include:1. Tropical rain forest2. Tropical dry forest3. Tropical savanna4. Desert5. Temperate grassland6. Temperate woodlands/shrublands7. Temperate deciduous forest8. Northwestern coniferous forest9. Boreal forest10. Arctic tundra

CHAPTER 4 SECTION 3: LAND BIOMES

The two main factors that determine climate are temperature and precipitation

Both temp. and precipitation can be summarized on a graph called a climate diagram

A microclimate is a climate within a small area that differs significantly from the climate around it (example: San Francisco=certain streets within the city are blanketed with a thick fog, while the sun shines a few blocks away)

CLIMATE AND MICROCLIMATE

Each biome is defined by a unique set of abiotic factors, particularly climate, and has a characteristic ecological community.

Transitional areas between biomes =one biome’s plants and animals gradually become less frequent, while the organism characteristics of the adjacent biome becomes more frequent

BIOMES CONTINUED

Mountain ranges and polar ice caps do not fall into the major biome categories

Mountain ranges are found on all continents.

Abiotic and biotic conditions vary with elevation

As you move up from base of mountain to summit, temperature becomes colder and precipitation increases. Types of plants and animals change as a result.

OTHER LAND AREAS

Polar ice caps involve the polar regions that border the arctic tundra and are cold year-round***READ PAGES 98-105 AND COMPLETE 4-3

GUIDED READING WORKSHEETS***

3/4 of earth’s surface is covered in water Water communities include oceans,

streams, lakes, and marshes. Water communities are controlled by biotic

and a biotic factors including light, nutrient availability and oxygen.

4-4: AQUATIC ECOSYSTEMS

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

1. Aquatic ecosystems are grouped according to the abiotic factors that affect them

2. Land biomes are grouped geographically

1. Depth of water: distance from the shore determines the amount of light organisms receive

2. Water chemistry: amount of dissolved chemicals (salts, nutrients, oxygen) on which life depends

3. Latitude: aquatic ecosystems in polar, temperate, and tropical oceans all have distinctive characteristics

FACTORS AFFECTING AQUATIC ECOSYSTEMS

Two main types: flowing water and standing water

1. Flowing water ecosystems: a) rivers, streams, creeks, brooksb) Organisms are well adapted to the rate of flowc) Originate in mountains or hills from underground

sourcesd) Rapid water has a higher amount of distilled water but

little plant lifee) Moving downhill, sediments build up and plants

establish themselvesf) Slow moving water through flat areas where turtles and

river otters make their homes

FRESHWATER ECOSYSTEMS

2. Standing water ecosystemsa) Lakes and pondsb) Water circulates within them and usually flows in and

outc) Circulation distributes heat, oxygen, and nutrientsd) Plankton live here: tiny free floating or weakly

swimming organisms that live in freshwater and saltwater environments

e) Phytoplankton: single celled algae supported by nutrients in water and form the base of aquatic food webs

f) Zooplankton: planktonic animals that feed on phytoplankton

A wetland is an ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year

A wetland is usually a mixture of salt and freshwater

It is a breeding ground for insects, fish, amphibians, and migratory birds

FRESHWATER WETLANDS

1. Bogs: usually form in depressions called “kettle holes” left by icy sheets that melted thousands of years ago. Sphagnum moss grows here because water is acidic.

2. Marshes: shallow wetlands along rivers. They may be underwater for all or part of a year. Contains cattails and tall, grasslike plants

3. Swamps: slowly moving water that looks like a flooded forest. Contains trees and shrubs.

THREE MAIN TYPES OF FRESHWATER WETLANDS

Wetlands formed where rivers meet the sea Mixture of freshwater and saltwater Affected by the rise and fall of ocean tides Most are shallow, so sunlight reaches the

bottom to begin photosynthesis Primary producers are plants, algae and bacteria Most primary production is NOT consumed by

herbivores. Instead, it enters the food web as detritus=tiny pieces of organic material that provide food for organisms at the base of the estuary’s food web (ex. Clams, worms, sponges)

ESTUARIES

Salt marshes: temperate zone estuaries dominated by salt tolerant grasses above the low tide line and sea grasses under water

Mangrove swamps: coastal wetlands that are widespread across tropical regions. Dominant plants are salt tolerant trees and sea grasses. It is a valuable nursery for fish and shellfish. The largest in the United States is the Florida Everglades National Park

1. Photic zone: well lit upper layer where photosynthesis takes place. Depth of 200 meters; where algae and other producers grow

2. Aphotic zone: permanently dark layer just beneath the photic zone; chemosynthetic autotrophs can survive here

MARINE ECOSYSTEMS

Ocean zones are based on the depth and distance from the shore. They are the intertidal zone, the coastal ocean, and the open ocean.

Each zone supports distinct ecological communities

OCEAN ZONES

Regular and extreme changes in surroundings

One or two times, the zone is submerged in seawater. The rest of the time, it is exposed to air, sun and temperature changes

Battered by waves and strong currents

INTERTIDAL ZONE

Exists in temperate regions where exposed rocks line the shore

Barnacles and seaweed permanently attach themselves to rocks

Snails and sea urchins cling to rocks by their feet

Zonation=prominent, horizontal banding of organisms that live in a particular habitat. In the rocky intertidal zone, each band can be distinguished by differences in color or shape of the major organisms

ROCKY INTERTIDAL ZONE

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

It is the relatively shallow border that surrounds the continents.

Rich in plankton and other organisms Example: kelp forests=giant brown algae

that can grow as much as 50 cm a day. It is found in cold, temperate seas around the world. They support a food web of snails, sea otters, fish, seals, and whales

COASTAL OCEAN

Named for the coral animals whose hard, calcium carbonate skeletons make up their primary structure

Most diverse and productive environments on earth

Coral animals=use tentacles to capture and eat microscopic creatures; they cannot grow in cold water or water low in salt. They live in symbiosis with algae.

Almost all growth in a coral reef occurs within 40m of the surface

CORAL REEFS

The oceanic zone begins at the edge of the continental shelf and extends outward

it is the largest marine zone covering more than 90 % of surface area of the world’s oceans

Organisms are exposed to high pressure, frigid temperatures, and total darkness

Fish of all shapes and sizes dominate the open ocean (swordfish, octopus)

Dolphins and whales could live here, but must stay near the surface to breathe

OPEN OCEAN

The ocean floor Benthos=organisms that live attached to or near

the bottom (sea stars, sea anemones, marine worms)

The zone extends horizontally along the ocean floor from the coastal ocean through the open ocean

Benthic ecosystems depend on food from organisms that grow in the photic zone (producers)

They feed on pieces of dead organic material (detritus) that drift downward from the surface of the water

BENTHIC ZONE

Chemosynthetic bacteria= support life without light and photosynthesis

They live near deep-sea vents where superheated water boils out of cracks on the ocean floor

*Read pages 106-112 in your textbook. Complete guided reading worksheets

section 4-4.**Prepare for a test!!!!