1. Grasslands
Grassland-an ecosystem in which there is more water than in a desert, but not enough water to support a forest

2. Grasslands start at the edge of desert biome and stretch across the land to the forest biome
Found in Africa, central Asia, North America, South America, and Australia
In US, they stretch from Rocky Mountains in west to forests of the East
Stretch from Canada down to Mexico
CLIMATE
Wetter than deserts
The dry air that blows over the east of the mountain to form deserts, eventually gains enough moisture for rain to fall
Desert-grassland boundary-the area b/n deserts and grasslands where increased rainfall enables some grasses to grow
Long-term climate changes can cause biome changes
If enough rain falls, a desert can become a grassland
If rainfall decreases enough, a grassland can become a desert

3. ORGANISMS
Both abiotic and biotic factors determine what organisms live in grasslands
Grasses are the most common
ABIOTIC FACTORS
Hot, dry summers
Rainfall is the limiting factor
w/out rain, grass won’t develop
Also, natural fires caused by lightning limit grassland development
Fires are common and keep # of trees and shrubs low
Most mass of trees and shrubs are aboveground, so they are vulnerable to fire
Grasses have most mass below ground, so they survive better
Rye plant is 2 meters high, but has 600 km of roots below

4. Fires also benefit grasslands by burning dead grass layer, making it into valuable nutrients
Nutrients create a fertilizer
Grasslands have a deep, fertile soil
Heat from fire helps germinate grass seeds
BIOTIC FACTORS
Grazing animals, ex: bison, are lawn mowers keeping vegetation low to ground
This keeps trees and shrubs too damaged to grow well
Burrowing animal, ex: earthworms, prairie dogs, and insects, make tunnels and dig.
This aerates the soil, giving more oxygen and nutrients to the grasses growing roots
Rain amounts affect size and texture of grasses
Short-grass prairies receive less rain
Used for cattle grazing and irrigated crops
Tall-grass prairies receive more rain
Used for tall crops like corn and wheat

5. When it rains is also important
Grasslands have rainy seasons and drought seasons
Experience cycles of heavy rain followed by long periods of little or no rain
Many plants adapted by becoming drought-resistant-trees and shrubs that survive in dry grasslands despite small amounts of rain
ANIMALS
All grasslands have large grazing animals: antelope and bison
They can run quickly from predators
Many animals feed on seeds and leaves of grass: grasshoppers, mice, gophers, prairie dogs, birds
Some animals are nocturnal to avoid predators and daytime heat,
They burrow underground
North American predators: coyotes, foxes, snakes, and birds
Grasslands can be three types of biomes: steppe, prairie, savanna

6. Types of Grasslands Steppes
Grasslands of short bunchgrasses that gets less than 50cm of rain/year
Must get more than 25cm rain/year or else it’s a desert
Temperatures range b/n -5 degrees and 30 degrees Celcius
Bunchgrasses-short, fine-bladed grasses that grow in a clump

7. Prairies
Grasslands characterized by rolling hills, plains, and sod-forming grasses
Most grains grow here to make breads and cereals
50-75 cm of rain/yr
Have sod-forming grasses- grasses that form a mat of soil and roots
This keeps soil close together and less moisture will evaporate
Also has a humus layer-layer of organic matter made from dead roots of the grasses
Humus provides fertile and moist layer

8. Savannas
Tropical or subtropical grasslands ranging from dry scrubland to wet, open woodland
Have rainy seasons and long droughts
Up to 150 cm rain/yr during short rainy season
Plants must be resistant to drought, fires, and grazing animals
Plants have runners-long, horizontal stems above and below ground
Grasses grow in tufts-large clumps of tall, coarse grasses
Tufts help protect them from grazing animals
Animals often eat in vertical feeding pattern-animals eat at different heights
this allows many animals to feed in the same area