Communities and ecosystems Essential questions What role do

Communities and ecosystems

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?

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

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

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

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

Correlation or causation?

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

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 http: //www. blueplanetbiomes. org/world_biomes. htm