Ch. 3: Communities and Biomes

What is Climate?

Weather Day-to-day condition of the Earth’s

atmosphere at a particular time and place Climate

Refers to the average year-after-year conditions of temperature and precipitation in a particular region

The Greenhouse Effect

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

Greenhouse Effect Natural situation in which heat is retained

by this layer of greenhouse gases

The Effects of Latitude on Climate

As a result of differences in latitude and thus the angle of heating, Earth has three main climate zones: polar, temperate, and tropical

Climate Zones

Heat Transport in the Biosphere

The unequal heating of the Earth’s surface drives wind and ocean currents, which transport heat throughout the biosphere

Biotic and Abiotic Factors

Biotic factors Include all living organisms that inhabit and

environment. Abiotic factors

The nonliving parts of an organism’s environment.

Examples: Air currents, soil, temperature, light and

moisture These factors typically determine species

survival.

Succession: Changes over Time

Ecological Succession The orderly, natural changes and species

replacements that take place in the communities of an ecosystem

Eventually a climax community (a stable, mature community that undergoes little or no change in species) results.

Primary Succession – the sequential development of living communities from bare rock Example – volcano erupting Pioneer species – the first species to populate

the area Secondary Succession – occurs when

communities are disrupted Examples – forest fire, hurricane

Biomes

Biome A complex of terrestrial communities that

covers a large area Characterized by certain soil and climate

conditions and particular plants and animals.

Tolerance Ability to survive and reproduce under

conditions that differ from their optimal conditions.

The Major Biomes

Includes: Tropical rain forest, tropical dry forest, tropical

savanna, desert, temperate grassland, temperate woodland and shrubland, temperate forest, northwestern coniferous forest, boreal forest, and tundra.

Two climate factors, temperature and precipitation, are the major limiting factors for the formation of terrestrial biomes.

Tropical Rain Forest Home to more species of organisms than

any other place on earth Warm temperatures (25°C), wet weather

(200 cm – 600 cm per year) Lush plant growth Located near the equator Vertical layering (ground, understory, &

canopy)

Tropical Rain Forest (cont.) Plants: hardwoods (mahogany), orchids,

moss and ferns Animals: monkeys, birds, bats,

chameleons, snakes, jaguar, ants, termites, and earthworms

Soil not nutrient rich

Tropical Dry Forest Rainfall is highly season Trees lose their leaves during the dry season -

deciduous Located just above and below the equator Plants: deciduous trees, orchids and bromeliads,

and aloes Animals: tigers, elephants, rhinoceroses,

termites, snakes and monitor lizards

Tropical Savanna Characterized by a cover of grasses Spotted with isolated shrubs and trees Compact soils and fairly frequent fires Plants: tall perennial grasses, trees and

shrubs Animals: lions, leopards, cheetahs,

hyenas, jackals, elephants, giraffes, zebras, eagles, ostriches, and termites

Desert Driest biome: less than 25cm of

precipitation annually Plants: cacti and small shrubs Animals: desert tortoises, snakes,

coyotes, hawks, owls, roadrunners, lizards, and scorpions

Grassland “Breadbaskets of the World” Large community covered with grasses and

similar small plants Experience a dry season Contains fewer than 10 – 15 trees per hectare Animals: grazing animals (bison), coyotes,

wolves, prairie dogs, insects, birds and reptiles Plants: any type of grasses (oats, rye, wheat)

Temperate Woodland and Shrubland Semiarid climate Characterized by open woodlands, large

areas of grasses and wildflowers with oak trees

Plants: evergreen shrubs, herbs Animals: coyotes, foxes, bobcats,

mountain lions, blacktailed deer, rabbits, quails, lizards and snakes

Temperate Forest Between 70 – 150 cm of precipitation

annually Top layer of soil is very rich Plants: Dominated by broad leaved

deciduous hardwoods, conifers, flowering shrubs, ferns

Animals: squirrels, deer, rabbits, mice, black bears, bluejays, and salamanders

This is where we live.

Northwestern Coniferous Forest Moist air from the Pacific Ocean provides

abundant rainfall Located along the northern California coast Plants: Douglas fir, Sitka spruce, western

hemlock, redwoods Animals: bears, elk and deer, beavers,

owls, bobcats and weasels

Boreal Forest (Taiga) Along the northern edge of the temperate

zone Winters are bitterly cold but summers are

mild Acidic nutrient-poor soil Plants: spruce, fir, berry-bearing shrubs Animals: lynxes, timber wolves, moose,

beavers, migratory birds

Tundra Treeless land with long summer days and

short periods of winter sunlight Temperatures never rise above freezing

for long Permafrost – permanently frozen ground

under the topsoil Thin topsoil can only support shallow-

rooted grasses and other small plants; lacks nutrients

Tundra Process of decay is slow because of cold

temperatures Short growing season Plants: grasses, dwarf shrubs, & cushion

plants Animals: migratory waterfowl, shore birds,

musk ox, artic foxes, caribou and lemming

Aquatic Ecosystems

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

Freshwater Ecosystems

Two main types: Flowing-water ecosystems

Rivers, stream, creeks and brooks Originate in mountains or from an

underground water source Upstream: insect larvae, catfish, trout Downstream: turtles, beavers and river otters

Two main types: (cont.) Standing-water ecosystems

Lakes and ponds Water is usually circulating within them Organisms: plankton ( tiny, free-floating

organisms) Phytoplankton – algae Zooplankton – animal-like that feed on

phytoplankton

Freshwater Wetlands Wetland – an ecosystem in which water

either covers the soil or is present at or near the surface of the soil for part of the year

Water may be flowing or standing and can be freshwater, salt water or brackish

3 main types: bogs, marshes and swamps

Estuaries

Estuaries wetlands formed where rives meet the

sea Affected by the high and low tide Producers: plants, algae and bacteria Detritus – organic matter that provides

food for clams, worms and sponges Serve as spawning grounds for shrimp

and crabs

Salt marshes temperate-zone estuaries dominated by salt-

tolerant grasses Located along eastern North America from

Maine to Georgia Mangrove swamps

Coastal wetlands along the tropical regions including Florida (Everglades) and Hawaii

Plants: salt-tolerant trees and seagrasses Serve as nurseries for fish and shellfish

Marine Ecosystems

Photic zone – shallow enough for sunlight Photosynthesis occurs here through

algae and other producers Aphotic zone – deeper water that

never receives sunlight Chemosynthetic autotrophs live here

Marine Ecosystems (continued)

Marine biologists divide the oceans into zones based on the depth and distance from the shore. Intertidal zone Coastal ocean Open ocean

Marine Ecosystems (continued)

Intertidal Zone Organisms that live here are exposed to

regular and extreme changes in their surroundings Submerged twice a day and exposed to air,

sunlight, and temperature changes rest of the day.

Zonation- prominent horizontal banding of organisms that live in a particular habitat

Marine Ecosystems (continued)

Coastal Ocean Extends from the low-tide mark to the outer

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

Located in the photic zone and is rich in plankton and other organisms

Kelp forests – named for the giant brown algae that can grow up to 50 cm a day Most productive coastal ocean communities

Marine Ecosystems (continued)

Coral Reefs Named for the coral animals whose hard,

calcium carbonate skeletons make up their primary structure

Most diverse and productive environment Thrive only in brightly lit areas within 40

meters of the surface

Marine Ecosystems (continued)

Open Ocean Begins at the edge of the continental

shelf and extends outward Largest of the marine zone (covers more

than 90% of the surface of the world’s oceans)

Depth is from 500 m to 11,000 m Organisms exposed to high pressure,

frigid temperatures, and total darkness

Marine Ecosystems (continued)

Open Ocean (continued) Has very low levels of nutrients and

supports only the smallest producers Most of the Earth’s photosynthetic

production occurs in the part of the open ocean in the photic zone (due to the enormous area)

Common organisms: squid, octopus, whale, dolphins, swordfish, variety of fish

Marine Ecosystems (continued)

Benthic Zone Extends from horizontally along the

ocean floor from the coastal ocean through the open ocean

Benthos – organisms (such as sea stars, anemones, and marine worms) that live on the ocean’s floor