GRASSLAND BIOMES

1. GRASSLAND BIOMES ENVIRONMENTAL SCIENCE - CHAPTER 8

2. GRASSLANDS • Grasses feed thousands all over the world. • Grasses are found on every continent on Earth. • All grains (wheat, rice, oats) are grasses. • Grasses can survive vast temperature changes (from -25oC to 70oC).

3. GRASSLAND DEFINED • Grassland - ecosystem with more water than a desert but not enough to support a forest • Found in every continent Africa, central Asia, North America, South America, Australia EXCEPT Antarctica • Desert-grassland boundary – rainfall amount determines whether land becomes desert or grassland

4. Grassland Organisms • Most common plants are grasses • Most of the grass plant is underground (roots) • This protects the grasses from fire and drought. Ex: A single rye plant can grow as tall as 2 meters and have roots spread out as far as 600 km!

5. GRASSLAND FACTS • Rainfall is the most important abiotic limiting factor. • Rainfall amount determines the kinds of grasses and how tall they will grow. Ex: less rain = short/fine-leaf grasses more rain = tall/broad-leaf grasses • Temperature ranges from -25oC to 70oC • FIRES eliminate competing trees and shrubs clear away all dead grasses that build up release nutrients and minerals from the soil help some grass seeds to germinate

6. Grassland Facts • Biotic factors can also affect grassland organisms. Ex: Large populations of grazing animals will prevent trees and shrubs from growing around a grassland pond Two seasons: Rainy seasons – short cycles of heavy rain Drought seasons – longer periods of little or no rain Ex: Savanna in Africa has both rainy and drought seasons

7. Steppe Facts Steppes – • gets less than 50 cm rain per year -most rain evaporates quickly • found on western and southwestern edges of deserts • Have high winds • Broad temperature range from -5oC to 30oC

8. Steppe Plants • Bunchgrasses are short fine-blade grasses that grow in a clump • Short fine blades of grass and clumping the roots prevent water loss • Use high winds to help disperse plant seeds to new growing areas • Roots can grow as deep as 50 cm • Freeze resistant

9. Steppe Animals • Adaptations to grassland include migrating, hibernating and burrowing underground. • Graze on grass late afternoon to early morning (hot) . • Burrow underground during the cold periods • Migrate with the availability of grasses Mongolian horse lemming Bactrian camel Steppe wildcat

10. Prairie Facts • Grasslands characterized by rolling hills, plains and sod formation • Rainfall is 50-75 cm per year • Soil holds water – grass roots form mats with the soil called sod • When the sod grasses die they form high nutrient organic material called humus

11. Prairie Plants • Grasses form sod mats • Hold water well • Wind disperse grass seeds • Grasses aren’t harmed by large populations of herbivores because of their adaptation of migration.

12. Prairie Animals • Prairies support large populations of herbivores • Animals use migration, hibernation and burrowing as adaptations to the temperature extremes • Prairie animals help the prairie biome ecosystem. Large populations of prairie dogs (rodents) create “towns”- a series of connecting underground burrows • Towns help aerate the soil Bison Prairie chicken Prairie fox Prairie dogs Black-footed ferret

13. AMERICAN DUST-BOWL • 1934-1938 an estimated 2.5 million people were forced to leave their farms and ranches. • Major environmental disaster (150,000 square miles of soil loss, dust storms ) • Causes: strong winds combined with poor farming practices and drought • Locations: Montana, North and South Dakota, Oklahoma, Kansas, Texas, Colorado, New Mexico and Mexico

14. Savannas • Tropical grasslands ranging from dry scrubland to wet, open woodland. • Mainly in central Africa, with small areas in India, southeastern Asia, northern Australia, llanos in Venezuela and Campos in Brazil • Short rainy seasons followed by long periods of drought

15. Savanna Plants • Plants must be resistant to heat, drought, fires and grazing animals. • Adaptations include: Rapid growth – savanna plants grow quickly. Runners – long horizontal stems above and below the ground – plants spread quickly and are protected from fire. Tufts – are large clumps of tall coarse grasses. Thorns – trees and shrubs grow spike like thorns or sharp leaves to prevent herbivores from eating them. Ex: Trees - Acacia, Baobab, Grasses - Rhodes, red oak, elephant, star and lemon , Shrubs – aloe candelabra tree Baobab tree only has leaves in the short rainy season. Acacia trees grow leaves only at the top of the branches and send out a chemical that make the leaves inedible after a giraffe eats one mouthful and one tree sends chemical signals to warn he surrounding trees.

16. Savanna Animals • Must take advantage of short rainy season • Adaptations: Migrate with food availability Reproduce during rainy season Vertical feeding pattern animal height determines what plants they eat this allows many animals to occupy smaller more specific niches Ex: lions, cheetah, springbok, elephant, rhino, Weaver bird, secretary bird