6

Major Ecosystems of the World

Earth’s Major Biomes 

Biome A

large, relatively distinct terrestrial region with a similar:  climate

soil, plants, & animals  regardless of where it occurs in the world 

Nine major biomes (on land)



Location of each biome is primarily determined by:  Temperature

(varies with both latitude and elevation)

 Precipitation

© 2012 John Wiley & Sons, Inc. All rights reserved.

Not in any order 1) Tundra 2) Boreal forests 3) Temperate rainforests 4) Temperate deciduous forest 5) Grasslands 6) Chaparral 7) Desert 8) Savana 9) tropical forests

Not on land 1) Aquatic Eco 2) Freshwater 3) River & Streams 4) Lakes & ponds 5) Marsh & Swamp 6) Estuaries 7) Intertidal 8) Benthic 9) Coral Reef

© 2012 John Wiley & Sons, Inc. All rights reserved.

Tundra Treeless biome in the far north harsh, cold winters and extremely short summers  



  

Precipitation (10–25 cm/yr) Short growing season (50–160 days)) Nutrient poor soils with organic material Low species richness Vegetation is mostly grasses Very simple food web

little

© 2012 John Wiley & Sons, Inc. All rights reserved.

Boreal Forests A region of coniferous forests in the northern hemisphere Just south of tundra   

 





Worlds largest (on land) Covers 11% of earth’s land Biome Growing Season (A little longer than tundra) Precipitation (~ 50 cm/yr) Soils - acidic & mineral poor Vegetation drought resistant conifers Mostly small animals & migrating birds Some large animals are present © 2012 John Wiley & Sons, Inc. All rights reserved.

Temperate Rainforest Coniferous biome with cool weather, dense fog & high precipitation 

Precipitation (> 127 cm/yr)  Heaviest



in winter

Temperature  Winters

are mild  Summers are cool 

Ex: Northwest US

Soils - nutrient-poor, but high in organic material (dropped needles) 



Note Heavily logged

Cool temperatures slow decomposition

Very high species richness 

cool climate animal life © 2012 John Wiley & Sons, Inc. All rights reserved.

Temperature Deciduous Forests occurs in temperate areas with a moderate amount of precipitation 



Precipitation (75–150 cm/yr) Temperature  Hot

 

Topsoil is rich in organic material Vegetation is primarily deciduous 



Oak, maple

(leaves fall off)

Animals 



summers & cold winters

Deer, bear, and small animals

Note 

Most of biome has been regenerated after farming and timber harvest

© 2012 John Wiley & Sons, Inc. All rights reserved.

Grassland 



Hot summers, cold winters & too little precipitation to support trees Precipitation  25–75

cm/yr

Soil has thick, organic material  Tall & Short grass prairies  Animals 





Once covered with bison no longer Smaller animals are still present (ex: prairie dogs)

Note: 90% of this biome has been lost to farmland

© 2012 John Wiley & Sons, Inc. All rights reserved.

Chaparral Also called a Mediterranean Climate 

(So. Cal-yup your living in it)

Temperature  Mild,

moist winters  Hot, dry summers 

Soil is thin and often not fertile  Dense

growth of evergreen shrubs  Lush during the growing season Mule deer, chipmunks, many species of birds



Frequent fires © 2012 John Wiley & Sons, Inc. All rights reserved.

Deserts lack of precipitation limits plant growth 

Temperature  Can

very greatly in 24-hr period, as well as yearly (based on location)



Precipitation (< 25 cm/yr)



Soils low in nutrients and high in salts



Vegetation sparse  cactus



and sagebrush

Animals are very small to regulate temperature © 2012 John Wiley & Sons, Inc. All rights reserved.

Savanna Tropical grassland with widely scattered trees    

Temperature - Varies little throughout the year Soil low in nutrients due to leaching Vegetation - expanses of grass, occasional Acacia trees Precipitation (76-150 cm/yr)  Seasons

regulated by precipitation, not temperature



Animals Herds of hoofed animals  Large predators - lions, hyenas, etc 

© 2012 John Wiley & Sons, Inc. All rights reserved.

Tropical Rainforest Lush, species-rich biome 



Occurs where climate is warm & moist throughout the year Precipitation  200–450



Weathered, nutrient-poor soil  Nutrients

 

cm/yr tied up in vegetation, not soil

Very productive biome Most species-rich biome  Most

abundant insect, reptiles & amphibians on earth © 2012 John Wiley & Sons, Inc. All rights reserved.

Vertical Zonation 

Increasing in elevation has similar effect on ecosystem as traveling to higher latitudes

© 2012 John Wiley & Sons, Inc. All rights reserved.

Distribution of Terrestrial Biomes

Tundra 10-25 cm/yr Boreal Forests ~50 cm/yr Temp Rainforest >127 cm/yr Temp Deciduous 75-150 cm/yr Grasslands 24-75 cm/yr Chaparral 25-50 cm/yr Deserts