2.4.1-.2 Biomes

BIOME is the collection of ecosystems sharing similar climatic conditions.

Uneven Solar Heating and Latitude

Earth as a whole is in thermal equilibrium, but different latitudes are not. Moving masses of air and ocean currents transport energy from locations with a surplus to those with a deficit.

Cell 3 South

Cold,dry air falls

Moist air rises — rain

Cell 2 South

Cool, dryair falls

Cell 1 South

Moistair rises,cools, andreleasesmoistureas rain

Cell 1 North

Cool, dryair falls

Cell 2 North

Moist air rises — rain

Cell 3 NorthCold,dry airfalls

Polar capArctic tundra

60°

30°

0°

30°

60°

Polar cap

Evergreenconiferous forest

Temperate deciduousforest and grassland

Desert

Tropical deciduous forest

Equator Tropical rain forest

Tropical deciduous forest

DesertTemperate deciduousforest and grassland

Model of global air circulation and biomes.The direction of air flow and the ascent and descent of air masses in convection cells determine the earth’s climatic zones.

MountainIce and snow

Altitude

Tundra (herbs,lichens, mosses)ConiferousForest

Tropical Forest

DeciduousForest

Tropical Forest

DeciduousForest

ConiferousForest

Tundra (herbs,lichens, mosses)

Polar iceand snow

Latitude

Generalized effects of altitude and latitude on climate and biomes.Parallel changes in vegetation occur when moving from the Equator to the poles or from the lowlands to mountaintops.

DESERT BIOMES

Tropical desert(Saudi Arabia)

Polar desert(northwest China)

GRASSLAND BIOMES

Tropical grassland (savanna)(Harare, Zimbabwe)

Polar grassland (arctic tundra)(Fort Yukon, Alaska)

FOREST BIOMES

Tropical rain forest(Manaus, Brazil) Temperate deciduous forest

(Nashville, Tennessee)

AQUATIC BIOMES

Coral reefsRivers

Lakes MangrovesOcean

High tideLow tide

Coastal Zone

EstuarineZone

Continentalshelf

Open SeaSea level

Sun

Euphotic Zone

Bathyal Zone

Abyssal Zone

Depth inmeters

0

50

100

200 Phot

osyn

thes

is

500

1,000

1,500

2,000

3,000

4,000

5,000

10,000

Dar

knes

sTw

iligh

t

DIVERSITY is a generic term for heterogeneity. If may refer to:

1. Genetic diversity is the total number of genetic characteristics of a specific species.

2. Habitat diversity is the diversity of habitats in a given unit area.

3. Species diversitya. Species richness – total number of species.b. Species evenness – relative abundance of

each species.c. Species dominance – the most abundant

species.

Figure a and b have the same species

richness, but different

species evenness.

Changes in the distribution of animals with elevation on a typical mountain in Kenya.

Change in the relative abundance of a species over an area or a distance is referred to as an

ecological gradient.