Learning objectives

� Describe the major characteristics of biomes and their location on
the planet
� Predict biome based on temperature and precipitation (mean and variation)
� Describe the major plant and animal adaptations in each biome

Biomes

Regions characterized by distinct abiotic conditions and dominant
vegetation types

Deserts

Mostly near 30o N and S Cover 20% of
Earth's terrestrial surface Less than 50cm rainfall/yr
Convergent adaptations of plants and animals to conserve
water Cold deserts: vegetation primarily desert shrubs
Hot deserts: vegetation lacking or combination of shrubs and
succulents

Animal adaptations in deserts

Desert temperatures and precipitation

Tropical rainforests

Tropical Rainforest (equator to 23.50 N and
23.50 S)
Canopy: Multilayered and continuous, low light penetration.
Flora and Fauna: VERY diverse
High Temperature: ~ 25� C
Lots of rain: > 200 cm/yr
Nutrient Poor Soil: acidic, rapid decomposition

Plant adaptations in tropics

Tropical rain forests temperatures and precipitation

Temperate forests

Location: 30o to 50o latitude N and S
Temperature: Highly variable -20o C to 30� C
Precipitation: 75-150 cm evenly throughout year
Soil: fertile, with decaying litter
Canopy: light penetrates, diverse understory vegetation
Flora: Trees w/broad leaves that are lost annually

Plant adaptations in temperate forests

Temperate forests temperatures and precipitation

Grasslands

Tropical grasslands, aka savannas 0o - 20o latitude
- Semi-arid with seasonal rainfall
- Grasses are primary vegetation
- Fire is common

Plant adaptations in grasslands

Temperate grasslands temperatures and precipitation

Boreal forests (Taiga)

Location: 50o - 60o N
Temperatures - very low in winter (down to -
54oC) Precipitation - snow, 40-100 cm
annually. Soil - is thin, nutrient-poor, and acidic.
Canopy - low light penetration, limited understory
Flora - mostly of evergreen conifers

Plant adaptions in Taiga/boreal Forests

Taiga/boreal forests temperatures and precipitation

Tundra

Location: >60o N Extremely cold climate:
(-34� C, but the average summer temperature is 3-12� C) Low
biotic diversity Short growing/reproductive season
Permanently frozen subsoil: permafrost Simple
vegetation structure - low shrubs, sedges, reindeer mosses,
liverworts, and grasses

Plant adaptations in tundra

Tundra temperatures and precipitation