4-1 The Role of Climate

• Weather vs. Climate

– Weather: day-to-day condition of Earth’s atmosphere at a particular time & place

– Climate: the average, year-after-year conditions of temperature and precipitation in a particular region

• Influenced by: atmosphere trapping heat, latitude, winds & ocean currents, precipitation, shape & elevation of land masses

Greenhouse Effect

• Natural situation in which heat is retained in Earth’s atmosphere by carbon dioxide, methane, water vapor, and other gases

• Necessary to keep temperatures suitable for life

Sunlight

Some heat escapes into space

Greenhouse gases trap some heat

Atmosphere

Earth’s surface

The Effect of Latitude on Climate

• Latitude – Distance north or south of the equator

• Due to Earth’s tilt on its axis, solar radiation strikes different parts of the Earth’s surface at an angle that varies throughout the year.

• Produces three main climate zones – Polar zones

– Temperate zones (seasons)

– Tropical zone

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

• Unequal heating of Earth’s surface drives winds & ocean currents

• Winds form because warm air rises and cold air sinks

• Landmasses can interfere with movement of air masses – Mountains cause moist air to rise

– Air mass cools, moisture condenses, causes precipitation

– Causes a rain shadow (dry climate) on the far side of the mountains

Ecosystems are influenced by a combination of biological and physical factors.

Biotic Factors

• Biological influences (living components) – Animals

– Plants

– Fungi

– Protists

– bacteria

Abiotic Factors

• Physical factors (nonliving components) – Temperature

– Precipitation

– Humidity

– Wind

– Nutrients

– Soil

– Sunlight

Biotic Factors

ECOSYSTEM

Abiotic Factors

Habitat vs. Niche

• Habitat (address) – The area where an organism lives – Includes both biotic and abiotic factors

• Niche (occupation) – The full range of physical & biological conditions in

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

– Eating & obtaining food, physical conditions needed for survival, when & how it reproduces, etc.

– No two species can share the same niche in the same habitat

Bay-Breasted Warbler Feeds in the middle part of the tree

Yellow-Rumped Warbler Feeds in the lower part of the tree and at the bases of the middle branches

Cape May Warbler Feeds at the tips of branches near the top of the tree

Spruce tree

Describing a Niche

1. Place in a food web

2. Temperature range

3. Food (what it eats)

4. How it obtains food

5. What eats it

6. Physical conditions

7. When & how it reproduces

8. Any other important requirements, relationships, etc.

Community Interactions

• Competition

• Predation

• Symbiosis

– Mutualism

– Commensalism

– Parasitism

Competition

• Organisms of the same or different species attempt to use an ecological resource in the same place at the same time.

– Resource: any necessity of life (water, nutrients, light, food or space)

• Competitive exclusion principle

– No two species can occupy the same niche in the same habitat at the same time

Predation

• Interaction in which one organism captures and feeds on another organism

– Predator: organism that does the killing and eating

– Prey: the food organism

Symbiosis

• Any relationship in which two species live closely together

• Mutualism – Both species benefit from the relationship – Flowers & insects

• Commensalism – One benefits and the other is neither helped nor harmed – Barnacles attached to whales

• Parasitism – One organism (parasite) lives in or on another organism

(host) and harms it – Parasites usually weaken, but don’t kill, their hosts – Tapeworms living in mammals, fleas on mammals

Ecological Succession • Series of predictable changes that occurs in a

community over time

• Can result from slow changes in the physical environment or sudden disturbances from human activities

• Primary Succession – Occurs on surfaces where no soil exists

– Ex: Volcanic eruptions building new islands, rock after glaciers melt • Pioneer species: 1st species to populate an area

• Secondary Succession – Succession following a disturbance that destroys a

community without destroying the soil

– Ex: After wildfires or abandoned farmland

Biomes

• Complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals

• Not all kinds of organisms can live in every biome. – Adaptation: inherited characteristic that increases an

organism’s ability to survive and reproduce

– Tolerance: ability to survive and reproduce under conditions that differ from their optimal conditions

– Microclimate: the climate in a small area that differs from the climate around it

The Major Biomes

• Tropical rain forest

• Tropical dry forest

• Tropical savanna

• Desert

• Temperate grassland

• Temperate woodland and shrubland

• Temperate forest

• Northwestern coniferous forest

• Boreal forest

• Tundra

Aquatic Ecosystems

• Determined primarily by the depth, flow, temperature, and chemistry of the overlying water

• Grouped according to the abiotic factors that affect them (not geographically)

Freshwater Ecosystems

• Only 3% of Earth’s surface water is fresh water

• Flowing-Water Ecosystems

• Standing-Water Ecosystems

• Freshwater Wetlands

Flowing-Water Ecosystems

• Rivers, streams, creeks, brooks • Organisms adapted to rate of flow

– Ways to attach to plants or rocks – Streamlined bodies

• Usually originate in mountains from underground water source – Plenty of dissolved oxygen & little plant life at source – Sediments build up as water flows down hill & plants

establish themselves – As it slows downstream, may find turtles, beavers,

river otters

Standing-Water Ecosystems

• Lakes and ponds

• Water circulates within (not just flowing in and out) – Helps distribute heat, oxygen & nutrients throughout

the ecosystem

• Plankton – Tiny, free-floating, weakly swimming organisms

– Phytoplankton: single-celled algae; base of aquatic food webs

– Zooplankton: feed on phytoplankton

Go to Section:

Spoonbill

Duck

Dragonfly Phytoplankton

Frog Water lilies

Mosquito larvae

Snail

Diving beetle

Trout

Pickerel

Duckweed

Snail Benthic crustaceans

Hydra

Frogs lay eggs in the shallow water near shore.The eggs hatch in the water as tadpoles and move to the land as adults.

The shore is lined with grasses that provide shelter and nesting places for birds and other organisms.

The roots of water lilies cling to the pond bottom, while their leaves, on long flexible stems, float on the surface.

The bottom of the pond is inhabited by decomposers and other organisms that feed on particles drifting down from the surface.

Fish share the pond with turtles and other animals. Many of them feed on insects at the water’s edge.

Plankton and the organisms that feed on them live near the surface where there is enough sunlight for photosynthesis. Microscopic algae are among the most important producers.

Section 4-4

Freshwater Pond Ecosystem

Crayfish

Freshwater Wetlands

• wetland

– 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

– May be flowing or standing

– Fresh, salty or brackish (mixture of fresh & salt)

– Very productive ecosystems

– Bogs, marshes, swamps

Estuaries • Wetlands formed where rivers meet the sea

• Mixture of fresh water & salt water

• Affected by rise & fall of ocean tides

• Most primary production is not consumed by herbivores

– Instead enters the food web as detritus (particles of organic material that provide food for organisms at the base of the estuary’s food web)

• Support an astonishing amount of biomass – Spawning & nursery grounds for commercially important

fishes and for shellfish

• Salt marshes, mangrove swamps

Marine Ecosystems

• Oceans

• Photic zone

– Well-lit upper layer of the oceans

• Aphotic zone

– Permanently dark layer of the oceans below the photic zone

– Only producers here are chemosynthetic autotrophs

Intertidal Zone

• Organisms exposed to regular & extreme changes

– Submerged in water then exposed to air, sunlight & temperature changes

• Competition leads to zonation

– Prominent horizontal banding of organisms that live in a particular habitat

Coastal Ocean

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

• Often rich in plankton & other organisms

• Kelp forests

– Named for their dominant organism: a giant brown alga that can grow as much as 50 cm a day

Coral Reefs

• Diverse and productive environments named for the coral animals that make up their primary structure

• Found in warm, shallow water of tropical coastal oceans

• Among the most diverse & productive environments on Earth

Open Ocean

• Oceanic zone

• Begins at the edge of the continental shelf and extends outward

• Largest marine zone – More than 90% of the surface area of the world’s

oceans

• Low levels of nutrients, only the smallest producers, low productivity

• Swordfish, octopus, dolphins, whales

Benthic Zone

• Ocean floor

• Benthos

– Organisms that live attached to or near the ocean floor

• Often depend on food from organisms that grow in the photic zone

• Most feed on detritus (dead organic material)

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land

Coastal ocean

Open ocean

Ocean trench

Aphotic zone

Photic zone

Continental shelf

Continental slope and continental rise

Abyssal plain

200m

1000m

4000m

6000m

10,000m

Section 4-4

Figure 4-17 Zones of a Marine Ecosystem