1. Biomes
Chapter 21

2. Distribution of Life on Earth
Influenced by weather (short term) and climate (long term weather patterns)
Weather affects individuals; climate influences and limits the overall distribution of entire species

3. Weather & Climate are driven by the SUN
Solar energy that reaches Earth drives the wind, ocean currents and global water cycle

4. Physical factors influence Climate
Latitude- determines the angle at which the sun’s rays hit the earth- changes the temperature

5. Air Currents-
generated by earths rotation cause large regions to be warm & dry, warm & wet, cold & dry or cold & wet

6. Ocean currents
moderate near shore climates- coastal areas tend to have steadier temperatures because of the heat retained in the water

7. Continents & Mountains
Irregularly shaped continents alter the flow of wind & water and contribute to the irregular distribution of biomes
Mountains cause variation in altitude which affects temperature and modify rainfall patterns- rain shadows

8. Terrestrial Biomes
Biomes are generally named after the dominant vegetation

9. Tropical Rain Forests On & around the equator Temp. b/w 77 F- 86 F
RF inches
Dominated by huge broad leaf evergreens
Cover 6% of Earth’s surface
Largest amount of biodiversity (2/3 of worlds total species)
Soil is nutrient poor
Colorful birds, frogs, monkeys, insects,

11. Grasslands/Savannas Center of continents 10-30 in. of annual rain
Continuous cover of grass with almost no trees
Hot dry summers tolerated by grasses kills trees
Most fertile soil in the world
Animals:North America-bison, prairie dogs, Africa-zebra, cheetah, lions

13. Deserts Less then 10 inches of rain/year
Defined by lack of rain not heat
Found on every continent
Shallow rooted plants- areas of dirt surrounding them
Dominant plants cacti & other succulents
Might be hot during day and cold at night. Could be a cold desert (Asia)
Animals-scorpions, mountain lion, snakes

15. Deciduous Forests 30-60 in. of rain
Deciduous trees are the dominant species
4 distinct seasons
Warm summer, cold winter
50 F- avg. temperature
Oak, Beech, Maple,
Deer, squirrels, fox, black bears, frogs, snakes, brown bears, rabbits

17. Taiga- Northern Coniferous Forest
Winter long & cold- growing Season Short
Dominated by needle bearing evergreen coniferous trees, spruce, douglas, pine
Not many species live there- conditions too harsh
Lynx, grizzly bear, moose, wolf, wolverine, snowshoe hare
30” of precipitation annually,
30-50 F, can be below freezing at night in the summer

19. Tundra Winter -40 F Winds avg. 30-60 mph
10 inches of rain or less annually
Permafrost-permanently frozen ground
Shallow root growth
Flowers, moss, grasses, no trees
caribou, mosquitoes, birds, wolves, snowy owls, artic foxes, grizzly bears, polar bears

21. Freshwater Covers less then 1% of the earths surface
Rivers, streams, ponds, lakes & marshes
Distribution of life depends of light, nutrients & access to the bottom
Lakes have three life zones:
Littoral- edge
Limnetic- to the depth in which light penetrates the water
Profundal- too deep for photosynthesis

22. Lakes classified by nutrient content
Oligotrophic- low in nutrients