Terrestrial Biomes Deserts and Grasslands
Chapter 6
What is a biome?
Biome – a major
ecological
community type
Tropical rainforest
Temperate forest
Grassland
Desert
Tundra
Taiga
Climate
Climate:
“a region’s weather condition patterns
over a long period of time”
what causes one biome to develop rather than
another
Main abiotic factors that determine
climate are precipitation and temperature.
Temperature and
Precipitation
Controlled by:
Air circulation
Uneven heating of the earth’s surface
Seasonal changes
Earth’s rotation
Interrelated properties of air and water
Uneven heating of water and land
Air Circulation Patterns
Tundra
Temperature and
Precipitation
Controlled by:
Water circulation (ocean currents)
All the properties that affect air
circulation also affects water circulation
plus:
Water density
Redistribution of heat
World’s Ocean Currents
Terrestrial Biomes
All biomes of the same name have:
similar physical characteristics
similar ecological communities
Communities may have adaptations specific
to their climate.
Climate Characteristics
Climate characteristics are
determined by:
Wind patterns
Ocean Currents
Latitude
Altitude
Biomes are not uniform because of
microclimates.
Microclimates
Local climate conditions that are
different than the overall climate of
a particular region
Some microclimates can be extremely
large
Rainshadow effect
Rainshadow Effect
Deserts of the World
Deserts - Facts
“An area where evaporation exceeds
precipitation”
Make up about 30% of earth’s land
surface
Most are found between 30ON and
30OS latitude
Deserts - Facts
Experience a large daily temperature
range
Precipitation is <10” per year
Soils are hard, dry and sandy with
few nutrients
Many desert organisms rely on oases
and fog for moisture
Desert
There are three
categories of
desert based on:
temperature range
amount of
precipitation
vegetation/animal
species
Tropical deserts
Driest places on
earth (<5” rain/year)
Temperate deserts
Sometimes caused by
rainshadow effect
Cold deserts
Also called interior
deserts
Desert Plants
Called xerophytes
Adaptations:
Require few
nutrients
Require little water
Leaves are small,
thick and waxy or
have become spines
Can expand to hold
extra water
Desert Animals Adaptations
Usually nocturnal
Usually small
Hard shells or thick
skins
Poisonous
Hibernate or enter
suspended animation
during droughts
Can conserve water
Human Impacts on Deserts
1.
Urbanization
2. Agriculture
3. Depletion of
groundwater
Pollution and
general damage
Use of remote
areas for
specialized
purposes
So What????
Extremely fragile
ecosystems
Take a long time to
recover from damage
because of:
Slow nutrient cycling
Slow plant growth
Low species diversity
Water shortage
Grasslands
Region with enough annual precipitation to
support grass (some small trees)
Most are found in interiors of continents
Usually on leeward side of mountain ranges
Precipitation is erratic
Wildfires are common
Grasslands
Trees and shrubs cannot ‘take over’
grasslands because:
Seasonal drought
Grazing by large herbivores
Periodic wildfires
There are 3 major types of grassland.
Grassland type depends on temperature
and precipitation.
Tropical Grassland
Also called savanna
Cover large areas of
Africa, South America
and Australia
Warm weather year
round
3 Seasons – 1 dry season,
1 rainy season and 1 wet
season
Mostly grasses with
individual stands of
trees and shrubs
Savanna - Animals
Many species of small animals
Rodents, birds
Large populations of herbivores
Africa – Gazelles, wildebeest
Australia - kangaroo
Savanna Animals –
Herbivore Adaptations
Evolution of eating strategies to
minimize competition
By food type
Grazers
Browsers
By migration
By food height
Giraffes Elephant Zebra Gazelle 
Wildebeest
Savanna Animals –
Carnivore Adaptations
Eat both small and large animals
Small animals require more individuals per meal
Hunting strategy
Cooperative – lion
Solo – cheetah
Ambush – lion
Pursuit – cheetah
Scavenge – hyena, vulture, eagle
Temperate Grasslands
Vast expanses of grasses without trees
Summer hot/dry. Winter bitterly cold.
Wildfires common in summer and fall.
Soils are thick and fertile.
Found in interior of N. and S. America, and China
Temperate Grasslands - Plants
Similar to tropical grassland plants
Evolved to fit the environment
Drought tolerant
Extensive root systems
Reproduce by seed or rhizome
Regrow from bottom – very important to survival
Temperate Grasslands - Animals
Complex food webs
Animals are mostly
small
Herbivores – prairie
dogs, squirrels
Carnivores – coyotes,
snakes, foxes
Large carnivores
eliminated by hunters
and farmers
Human Impacts on Grasslands
Savannas- Burned to convert to cropland
Savanna and temperate grasslands – overgrazed by
domesticated livestock
Temperate grasslands – plowing to convert to
croplands
Arctic Tundra
Also called polar
grasslands because of
their location near the
North Pole
Winter is bitterly
cold, with ice, snow,
high winds and weeks
of total darkness.
Arctic Tundra - Facts
Treeless. Covered
with a thick, spongy
layer of low-growing
plants
Caused by
permafrost
Summer lasts 2
months. Gets warm
enough to melt the
upper soil layer
allowing plant growth.
Tundra - Animals
Temporary residents
Migrating/nesting
birds
Migrating
herbivores
Eat summer
vegetation
Migrating
carnivores
Follow the herbivore
herds
Tundra - Animals
Permanent residents –
Small herbivores
Lemmings, hare,
squirrel
Small carnivores
Snowy owl, arctic fox,
lynx
Adaptations
Thick coats
Live underground
Small size
Don’t hibernate
Arctic Plants
Small, low–growing with most of the plant
underground as roots and bulbs
Thick, waxy leaves above ground
Some dehydrate to prevent freezing
Do all of their growing, blooming and
seeding in the 2 month long summer.
Arctic Plants
Arctic heather
Labrador tea
Bearberries