GRASSLAND BIOMES ENVIRONMENTAL SCIENCE - CHAPTER 8

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

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

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

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

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

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

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

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

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

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.

Prairie Animals Prairies support large populations of herbivores Prairies support large populations of herbivores Animals use migration, hibernation and burrowing as adaptations to the temperature extremes 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 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 Towns help aerate the soil Prairie chicken Bison Prairie fox Prairie dogs Black-footed ferret

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

Savannas Tropical grasslands ranging from dry scrubland to wet, open woodland. 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 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 Short rainy seasons followed by long periods of drought

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.

Savanna Animals Must take advantage of short rainy season Must take advantage of short rainy season Adaptations: 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