1. BIOMES: CLIMATE AND LIFE
Different climates lead to different communities of organisms, especially vegetation.
Biomes – large land regions with similar:
Climate
Soil
Plants
animals
Each biome contains many ecosystems whose communities have adapted to differences in climate, soil, and other environmental factors.

2. Why are Biomes where they are?
Latitude
Solar Angles
Ocean Current and Wind
Distribute the extra heat energy at the equator towards the poles
Water stores and transfers the heat (phase changes)
P/E Ratio
Precipitation to evaporation ratio
Productivity
Greater in low latitudes
High sunlight, temperature, and moisture (photosynthesis)
Declines as you approach the poles

3. P/E Ratio Abiotic Factors Influencing Biomes
Insolation, precipitation, and temperature
Increasing Temperature causes increasing evaporation
Plants may be short of water even if it rains or snows a lot
When the P/E ratio is 1
P=E Soil is rich and fertile
More on productivity next week

4. Climate Change and biome Shift
There is evidence that biomes are moving
Examples:
Woodlands becoming savannahs
Tundra becoming shrubland
Who cares?
There are obstacles to
migration
Plants are slow
Some places are in trouble

5. Precipitation determines the type of vegetation in each biome.
Cold,
dry air
falls
Cell 3 North
Precipitation determines the type of vegetation in each biome.
Moist air rises — rain
Polar cap
Cell 2 North
Arctic tundra
Evergreen
coniferous forest
60°
Cool, dry
air falls
Temperate deciduous
forest and grassland
30°
Desert
Cell 1 North
Tropical deciduous forest
Moist air rises,
cools, and releases
Moisture as rain 0°
Equator
Tropical
rain forest
Tropical deciduous forest
30°
Desert
Figure 5.6
Natural capital: global air circulation and biomes. Heat and moisture are distributed over the earth’s surface by vertical currents, which form six giant convection cells at different latitudes. The resulting uneven distribution of heat and moisture over the planet’s surface leads to the forests, grasslands, and deserts that make up the earth’s biomes.
Cell 1 South
Temperate deciduous
forest and grassland
Cool, dry
air falls
60°
Cell 2 South
Polar cap
Cold,
dry air
falls
Moist air rises — rain
Cell 3 South
Fig. 5-6, p. 103

6. BIOMES: CLIMATE AND LIFE ON LAND
Ecotone: area between two biomes blending. Usually have more biodiversity.

7. BIOMES: CLIMATE AND LIFE ON LAND
Parallel changes in vegetation type:
equator to the poles
lowlands to mountaintops
Figure 5-11

8. Biome type is determined mostly by precipitation but also temperature and soil type
Figure 5-10