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