1. 22.4 Biomes page 758
Key Concepts: What are the six major biomes found on Earth? What factors determine the type of biome found in an area? What do freshwater and marine ecosystems include?
Key terms: biome, canopy, understory, desert, grassland, savanna, deciduous tree, coniferous tree, tundra, permafrost, estuary, intertidal zone, neritic zone

2. Biomes
A biome is a group of land ecosystems with similar climates and organisms
The six major biomes that most ecologists study are the rain forest, desert, grassland, deciduous forest, boreal forest, and tundra
It is mostly the climate – temperature and precipitation – in an area that determines its biome.

3. Rain forest biomes Temperate rain forests – have moderate temperatures
Northwestern coast of US receives more than 300 cm of rain per year. Huge trees grow.
Tropical rain forests – regions close to the equator
Canopy – leafy roof area
Second layer – understory
Forest floor

4. Desert biomes
Deserts are areas that receive less than 25 cm of rain per year
The amount of evaporation in a desert is greater than the precipitation.
Often undergo shifts in temperature from day to night
Organisms have to be accustomed to little rain and huge temperature differences

5. Grassland biomes Prairies
Temperatures are more comfortable than the desert
Gets more rain, but not enough for trees to grow
Area that is populated mostly by grasses and other non-woody plants
Most receive 25 to 75 cm of rain per year
Savannas receive 120 cm of rain per year and are located close to the equator

6. Deciduous forest biomes
Deciduous trees – trees that shed their leaves and grow new ones each year. Oaks and maples for example.
Forests receive enough rain to support tree growth, at least 50 cm per year.
Temps vary greatly
A lot of wildlife, but not during the winter.

7. Boreal forest biomes Colder climates
Boreal forest plants – coniferous trees – trees that produce their seeds in cones and have leaves shaped like needles.
Boreal forest is sometimes referred to by its Russian name, the taiga.
Trees are well adapted to cold
Animals – eat the seeds produced by the coniferous trees.

8. Tundra biomes
Tundra – extremely cold and dry biome. May receive no more precipitation than a desert. Most of the soil in the tundra is frozen all year. The frozen soil is called permafrost.
Tundra plants – mosses, grasses, shrubs

9. Mountains and ice
Some places are covered year round with ice, like mountain ranges.
These areas are not considered part of any particular biome.

10. Freshwater ecosystems
Freshwater ecosystems include streams, rivers, ponds and lakes.

11. Marine Ecosystems
Estuary – found where fresh water of a river meets the salt water of the ocean
Marine ecosystems include estuaries, intertidal zones, neritic zones, and the open ocean.

12. Intertidal zones
The area between the highest high-tide line and the lowest low-tide line.
Organisms survive pounding waves and sudden changes in water levels and temperatures.

13. Neritic Zones
Below the low-tide is a region of shallow water which extends over the continental shelf.
Photosynthesis can occur here.

14. Open Oceans Light penetrates only a few hundred meters deep.
The deep zone is located below the surface zone. The deep zone is almost totally dark.