1. Communities and ecosystems

2. Essential questions What role do autotrophs play in the community?
Why is there a limit to the number of trophic levels in an ecosystem?
To what extent are models useful representations of the real world?

3. Biomes versus Biospheres
Biosphere = all parts of the earth where organisms live
Biome = divisions of a biosphere
Major divisions: desert, grassland, shrubland, temperate deciduous forest, tropical forest, tundra

4. Temperature Latitudinal variation in the intensity of sunlight
Sun’s rays arrive almost perpendicular near the equator; more heat is delivered
Sun’s rays are spread out near the poles; less heat is delivered there

5. Precipitation High temperature  hot air rise
Hot air cools as it moves upward
Cold air holds less water vapor  Rain

6. Temperature and precipitation
Climograph = a graphical representation of mean annual temperature and precipitation

7. Correlation or causation?

8. Correlation!
Precipitation and temperature are not the only factors which affect the distribution of a species
E.g. soil nutrient availability can affect vegetation
Climographs are based on averages
Some areas may get regular precipitation throughout the year, while others with same annual precipitation have wet and dry seasons

9. Biomes research
Major biomes: desert, grassland, shrubland, temperate deciduous forest, tropical forest, tundra
Find the:
Location
Temperature (average in degree C in summer/winter)
Moisture (annual precipitation (cm/year))
Characteristics of vegetation and animals
Environmental challenges facing the biome