Ch. 4: Ecosystem and Communties

Ch. 4 Outline

• 4-1: The Role of Climate– What is Climate?– The Greenhouse Effect– The Effect of Latitude on Climate

• 4-2: What Shapes an Ecosystem– Biotic and Abiotic Factors– The Niche– Community Interactions– Ecological Succession

Ch. 4 Outline

• 4-3: Biomes– The Major Biomes– Other Land Area

• 4-4: Aquatic Ecosystem– Freshwater Ecosystems– Estuaries– Marine Ecosystems

What is Climate?• Weather: the day-to-day condition of

the Earth’s atmosphere at a particular time and place

• Climate: the average, year-after-year conditions and temperature and precipitation in a particular region– Caused by many factors including

latitude, wind currents, ocean currents, etc.

• The energy of incoming sunlight drives Earth’s weather and helps determine climate.

The Greenhouse Effect

• Temperature on Earth remain in a suitable range for life because of the atmosphere.– Carbon dioxide, methane, water

vapor and a few other atmospheric gases trap heat energy and maintain the Earth’s temperature range.

Greenhouse Effect

• Greenhouse effect: the natural situation in which heat is retained by the layer of gases around Earth– Gases in the atmosphere allow solar

energy in but do not allow it to pass out as easily (after it bounces off the Earth and heads in the other direction). This is how heat is trapped inside the Earth’s Atmosphere.

Greenhouse Effect

Sunlight

Some heatescapesinto space

Greenhousegases trapsome heat

Atmosphere

Earth’s surface

Greenhouse Effect

The Effect of Latitude on Climate

• Earth is tilted on its axis. As a result, sunlight hits the Earth at different angles.– Ex. In the tropics (around the

equator), sunlight hits directly year round.

• Because of this, earth has three different climate zones: polar, temperate, and tropical.

The Effect of Latitude on Climate

• Polar zone: cold areas where the sun’s rays strike the Earth at a low angle.– Around North and South Poles

• Temperate zones: located between polar zone and tropics– Climates ranges in these zones depending

on the season

• Tropical zone: near the equator– Receive direct sunlight year around.

The Effect of Latitude on Climate

Sunlight

Most direct sunlight

Sunlight

Sunlight

Sunlight

90°N North Pole

66.5°N

23.5°N

0°

23.5°S

66.5°S

90°S South Pole

Arctic circle

Tropic of Cancer

Equator

Tropic of Capricorn

Arctic circle

Different Latitudes

Heat Transport in the Biosphere• The unequal heating of Earth’s

surfaces drives wind and ocean currents

• Warm air tends to rise and cool air sinks. Warm air above the equator rises and cool air from the poles sinks. As a result, air currents (winds) form.– A similar pattern occurs in the oceans

• Winds and Ocean currents transport heat

Biotic and Abiotic Factors

• Ecosystems are influenced by a combination of biological (living) and physical (nonliving) factors.

• Biotic Factors: biological influences on an ecosystem

• Abiotic Factors: physical or non-living factors– Ex. Temperature, humidity, wind,

soil, etc…

Biotic and Abiotic Factors

• These types of factors together determine the survival and growth of an organism and the productivity of the ecosystem

• Habitat: the area in which an organism lives– Includes both abiotic and biotic

factors

Biotic and Abiotic Factors

Biotic Factors

ECOSYSTEM

Abiotic Factors

Community Interaction

• When organisms live together in a community, they constantly interact. These interactions (such as predation, competition, and symbiosis) greatly affect an ecosystem.

Community Interactions

• Competition:– Occurs when organisms try to use the

same resources at the same time and place

– Resource: any necessity of life (ex. Food)– Competitive exclusion principle: no

two organism can occupy the same niche in the same habitat

• One will always have a reproductive advantage over the other (even if very small) and will “win” over the other survive and pass on their genes!!!

Community Interaction• Predation

– Predation: an interaction in which one organism captures and feeds on another organism

– Predator vs. Prey

• Symbiosis:– Symbiosis: any relationship in which two

species live closely together– 3 main classes of symbiotic relationships:

1. Mutualism: Both Species benefit• Ex. Mycorrhizae

2. Commensalism: One benefits, the other is neither helped nor harmed

3. Parasitism: one benefits, the other is harmed• Ex. Tapeworms in mammal intestine.

Ecological Succession

• Ecosystems are always changing. They change in response to natural and human disturbances. Older inhabitants gradually die out and new organisms move in, causing even further change.

• Ecological succession: a series of predictable changes that occurs in a community over time.

Ecological Succession

• Two types of succession:1. Primary succession: Succession

that occurs where no soil exists– Ex. After a volcano Erupts– Pioneer species – first species to

populate the area (often lichens)

2. Secondary Succession: occurs when changes happen without removing the soil.– Ex. When a forest is cleared for

farming.

Biomes

• Biome: a complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular groups of plants and animals

• Plants and animals have specific adaptations to help them survive in a particular biome.– Ex. Leaves of cacti are small to prevent

water loss.

The Major Biomes• Tropical Rain Forest• Tropical Dry Forest• Tropical Savanna• Desert• Temperate Grassland• Temperate Woodland and Shrubland• Temperate Forest• Coniferous Forest• Boreal Forest• Tundra• All of these biomes are characterized by a unique set

of abiotic factors (mostly climate) and groups of plants and animals.

The Major BiomesTen Major Biomes

Biome Precipitation Temperature Soil Diversity Trees Grasses

Tropical Rain Forest

high hot poor high dense sparse

Tropical Dry Forest variable mild rich moderate medium medium

Tropical Savanna variable mild clay moderate sparse dense

Desert low variable poor moderate sparse sparse

Temperate Grassland

moderate summer hot rich moderate absent dense

Temperate woodland and Shrubland

summer low, winter moderate

summer hot poor low medium medium

Temperate Forest moderate summer moderate, winter cold

rich high dense sparse

Northwestern Coniferous Forest

high summer mild, winter cold

rocky, acidic low dense sparse

Boreal Forest moderate summer mild, winter cool

poor, acidic moderate dense sparse

Tundra low summer mild, winter cold

poor low absent medium

World’s Major Biomes

Tropical rain forest

Tropical dry forest

Tropical savanna Temperate woodlandand shrubland

Desert

Temperate grassland

Boreal forest(Taiga)

Northwesternconiferous forest

Temperate forest

Mountains andice caps

Tundra

Other Land Areas

• Some areas of Earth do not fall neatly into a major biome category– Ex. Mountain Ranges and Polar Ice Caps

• Mountain ranges:– On mountains, abiotic and biotic

conditions vary with elevation

• Polar Ice Caps:– Cold and Icy all year round– Dominant life includes penguins and other

marine mammals (in Antarctica) and polar bears and insects (North Pole)

Aquatic Ecosystems

• Almost ¾ of the Earth is covered in Water. Aquatic ecosystems are determined primarily by the depth, flow, temperature, and chemistry of the overlying water.

• Aquatic biomes are mostly grouped by the abiotic factors that affect them, rather then geography.

Freshwater Ecosystems

• Only 3% of the surface water on Earth is Fresh water.

• Types of Freshwater ecosystems:– Flowing-water Ecosystems

• Rivers, Streams, creeks• Organisms there have adapted to the

rate of flow– Ex. Anchoring Structures

Freshwater Ecosystem

• Standing Water Ecosystems– Lakes and ponds– Water circulates within them to

distribute nutrients– Provide habitats for plankton: tiny,

free-floating organisms• Ex. Phytoplankton – type of algae• Ex. Zooplankton – animals that feed

on phytoplankton

Freshwater Ecosystems

• Freshwater Wetlands– Wetland: Ecosystem in which water

covers the soil (or at least near the surface of soil) for part of the year.

– Water may be standing or flowing– Freshwater or saltwater (brackish)– Common breeding ground for many

animals– Three types: bogs, marshes,

swamps

Freshwater Ecosystem

Duck

DragonflyPhytoplankton

FrogWater lilies

Mosquitolarvae

SnailDivingbeetle

Trout

Pickerel

Duckweed

Snail Benthiccrustaceans

Hydra

Frogs lay eggs in the shallowwater near shore.The eggs hatch in the water as tadpolesand move to the land as adults.

The shore is lined with grasses that provide shelter and nestingplaces for birds and otherorganisms.

The roots of water liliescling to the pond bottom,while their leaves, on longflexible stems, float on thesurface.

The bottom of the pond isinhabited by decomposers andother organisms that feed onparticles drifting down from thesurface.

Fish share the pondwith turtles and other animals. Many of them feed on insectsat the water’s edge.

Plankton and the organisms thatfeed on them live near the surfacewhere there is enough sunlight forphotosynthesis. Microscopic algaeare among the most importantproducers.

Crayfish

Spoonbill

Estuaries

• Estuaries: Wetlands formed where rivers meet the sea

• They contain a mixture of fresh and salt water. Most are shallow so sunlight reaches the bottom (photosynthesis can happen there!)

Estuaries• Primary producers there: Plants, algae,

bacteria• Most organic matter is not consumed by

herbivores, but enters the food web as detritus– Detritus: tiny pieces of organic material

• Clams, worms, and sponges all feed on detritus.

• Estuaries support a large amount of biomass. Many fish are born there. Other animals feed and grow in estuaries, where they head out to sea to mature but return to reproduce.

Estuaries

• Salt Marshes: Temperate-zone estuaries dominated by salt-tolerant grasses and seagrasses underwater.– Found on East Coast of North America.

• Mangrove swamps: found in tropical regions, have salt-tolerant trees called mangroves– Ex. Florida’s Everglades National Park

Marine Ecosystems• Photic zone: Upper layer of water where

photosynthesis can occur• Aphotic zone: no light penetrates the

water• In addition to the division between the

photic and aphotic zone, scientists divide the ocean into zones based on the depth and distance from shore– Intertidal zone– Coastal Ocean– Open Ocean

• Benthic zone: covers ocean floor

Zones of the Marine Ecosystemland

Coastalocean

Openocean

Oceantrench

Aphotic zone

Photic zone

Continentalshelf

Continental slope andcontinental rise

Abyssalplain

200m

1000m

4000m

6000m

10,000m

Marine Ecosystem

• Intertidal Zone– Organisms that live here are

exposed to many changes in their surroundings. Competition often leads to zonation.•Zonation: the horizontal banding of

organisms that live in a particular habitat

Marine Ecosystem

• Coastal Ocean– Extends from the low-tide mark to

the outer edge of the continental shelf (the shallow border that surrounds the continents).

– Most of the coastal oceans fall in the photic zone so it is rich in many organisms

– In tropical coastal oceans, coral reefs exist

Marine Ecosystem

• Open Ocean– Begins at the edge of the

continental shelf and extends outward. It covers more than 90% of the surface area of the world’s oceans.

– Productivity here is low because there are low levels of nutrients deep in the ocean. Fish dominate the open ocean.

Benthic Zone

• The Ocean Floor• Benthos: Organisms that live

attached to or near the ocean floor– Ex. Sea Stars

• Depends on food from organisms that grow in the photic zone.

• Detritus that rains down to the floor.