Chapter 4

Ecosystems and Communities

4-1 The Role of Climate

Organisms vary in their “ideal” conditions

Also vary in tolerance to change

Many of these conditions or changes refer to climate/weather

Weather vs. Climate

Weather: conditions at a particular time and place

Climate: average conditions in a particular region

Effected by: atmosphere, latitude, winds, currents, precipitation, etc.

GreenhouseEffect

Natural situation in which heat is retained by layer of gases (CO2, methane)

Atmosphere acts as a natural insulator

Would be 30 degrees cooler without

Latitude

Polar zones- always cold

Temperate zones- varies hot/cold

Tropical zones- always hot

Heat transfer by:

Water- currents

Air- hot air rises/cool air falls (winds)

4-2 What shapesan ecosystem?

Habitat: area where an organism lives

Made up of:

Biotic factors: biological influences

Competitors, predators, prey

Abiotic factors: nonliving influences

Climate, nutrient availability

Niche

All factors that influence an ecosystem and how the organism uses them

The “role” of an organism

Competition Exclusion Principle: no 2 organisms can have the same niche

Ex: warbler bird

Community Interactions

Competition: attempt to use same resource at same place/same time

Predation: one organisms feeds on another

Symbiosis: two species in a relationship together

Types of Symbiosis

Mutualism: both benefit

Ex: flowers and insects

Commensalism: 1 benefits, other not effected

Ex: barnacle and whale

Parasitism: 1 benefits, other is harmed

Lives on/inside “host”- does NOT kill

Ex: tapeworm, ticks

Ecological Succession

Gradual change after a disturbance (natural or man-made)

Primary: succession when there is no soil

Pioneer species: first to populate an area

Secondary: succession when soil is still there

4-3 Biomes

Biome: group of communities covering a large area

Characterized by:

soil,

climate

specific plants and animals

The Biomes:

1. Tropical rain forest (ex: Brazil)

Hot and wet

Ferns, monkeys, toucans

2. Tropical dry forest (ex: India)

Warm with wet and dry seasons

Deciduous trees, tigers, elephants

3. Tropical savanna (ex: Kenya)

Warm with seasonal rain, lightning fires

Grasses, shrubs, lions, hyenas

4. Desert (ex: Arizona)

Low precipitation (dry), variable temps.

Cactus, snakes, lizard

5. Temperate grassland (ex: Texas)

Hot/cold seasons, average precipitation, fertile soil

Grasses, bison, grasshoppers

6. Temperate woodland (ex: Los Angeles)

Hot, dry summer and cool. wet winter

Evergreens, coyote, mountain lion

7. Temperate forest (ex: Philadelphia)

Moderate winter, warm summer, year round rain

Moss, coniferous trees, deer, squirrel

8. Northwestern coniferous forest (ex: Seattle)

Mild temps., cool, dry summer- otherwise wet

Conifer trees (redwood), bears

9. Boreal forest/ Taiga (ex: northern Europe)

Long, cold winter, short, dry summer

Fir trees, lynx, moose

10. Tundra (ex: Alaska)

Permafrost- layer of permanent frozen soil

Short grass, caribou, owl

Other land areas:

Mountain ranges (ex: WA state)

Factors change with elevation

Polar ice caps (ex: Antarctica)

Border tundra

Polar bears, insects

4-4 Aquatic Ecosystems

Grouped by abiotic factors

Depth (amount of light)

Nutrients available

O2 available

Freshwater (only 3%)

Flowing water- organisms adapt to the flow

Standing water- flow in and circulation of nutrients, O2 and heat

Freshwater wetlands- bogs, marshes and swamps- very diverse!

Estuaries

Wetlands where rivers meet the sea

Detritus = lots of biomass

Ideal for feeding, breeding, nesting, spawning

Ex: salt marshes and mangrove swamps

Salt tolerant

Marine Ecosystems

Photic zone: well-lit upper layer

Aphotic zone: dark (200m and deeper)

Marine Zones

1. intertidal

Extreme changes with tides

Hot and dry to covered in water

Waves and currents

2. coastal ocean

Low tide mark to continental shelf

Photic areas = phytoplankton

Ex: kelp forests and coral reefs

3. open ocean

Continental shelf outwards

Low nutrients = low productivity

4. benthic- along ocean floor

Benthos: organisms that live here

Food depends on depth: photic producers,, detritus, chemosynthesis