Chapter 20 and 21 The biosphere

Biosphere The biosphere includes all places where organisms live on Earth

Biosphere The biosphere is divided into Biomes Biomes are large areas distinctive in habitat conditions and community structure Habitat conditions are shaped by Climate Topography Soils

Biosphere Climate is the average weather conditions over time Temperature, humidity, wind, precipitation, etc Climates are created by several factors

Biosphere Climate Seasonal Effects Daylength and temperature change due to the Earth’s tilted axis

Biosphere Climate Air Circulation Patterns The equator gets more solar energy Warms the air making it less dense Causes evaporation from the ocean Results in upward movement of warm moist air

Biosphere Climate Air Circulation Patterns Warm, moist air rises Cools, releasing moisture as rain creating an area of high rainfall (rain forests) Cooler air flows north and south Cooled, dry air descends near 30°N and S latitudes Creates an area of low rainfall (deserts) The air cycles back towards the equator Air warms and picks up moisture starting the cycle again Several bands of circulating air encompass the globe

Biosphere Climate Surface Wind Patterns Earth’s rotation curves the paths of the bands of air circulating the globe Winds curve towards the right in the Northern Hemisphere In the Southern Hemisphere the wind curves left Creates the prevailing winds (westerlies and easterlies) Doldrums occur where the winds are intermittent

Biosphere Climate Ocean Currents More sunlight at the equator warms the water ultimately creating water currents through the ocean Water temperatures contribute to regional differences in air temperature and rainfall

Figure 43.5 Major climate zones correlated with surface currents and surface drifts of the world ocean. Warm surface currents start moving from the equator toward the poles, but prevailing winds, Earth’s rotation, gravity, the shape of ocean basins, and landforms influence the direction of flow. Water temperatures, which differ with latitude and depth, contribute to regional differences in air temperature and rainfall. Fig. 43.5, p. 726

Biosphere Topography creates regional effects Local topography affects climate Proximity to oceans moderate climate Elevation Land masses: Rain Shadows Warm moist air along the coast Cools as the air rises over mountains (precipitation) Dry air descends and warms as it flows down the leeward side

A Prevailing winds move moisture inland from the Pacific Ocean. B Clouds pile up and rain forms on side of mountain range facing prevailing winds. moist habitats C Rain shadow on side facing away from the prevailing winds makes arid conditions. 4,000/ 75 3,000/ 85 2,000/25 1,800/ 125 moist habitats 1,000/25 1,000/ 85 15/ 25 Figure 43.6 Rain shadow effect. On the side of mountains facing away from prevailing winds, rainfall is light. Black numbers signify annual precipitation, in centimeters, averaged on both sides of the Sierra Nevada, a mountain range. White numbers signify elevations, in meters. Fig. 43.6.1, p. 727

Biosphere Soils Types of soil directly impacts what plants can grow and their productivity Soils differ in Texture (ratio of sand, silt, and clay) Structure (granular, blocky, etc) pH Fertility (nutrient availability)

Questions What is the biosphere? What is a biome? Warm air ______ (rises or lowers) and it holds ______ (more or less) water than cold air Based on the air circulation patterns where would you expect deserts to form? Based on the air circulation patterns where would you expect tropical rain forests to form? T or F A rain shadow results from movement of air over a mountain range

Biomes Desert High temperature (cools at night) Low rainfall (0-10cm) Vegetation: succulents, annuals Areas which receive more rainfall have a greater variety of plants Adapted to dry conditions Animals: reptiles, insects, small nocturnal mammals Air circulation patterns (30° latitude) and rain shadows create most deserts

Lowlands with lower rainfall Uplands with a bit more rainfall

Mojave Desert after the rains: annual poppies sprout, flower, produce seeds, and die in the few short weeks while there is moisture

Fennec Fox Jerboa

Biomes Grasslands Tropical to Temperate Rainfall 25-90 cm Vegetation: grass, forbs (wild flowers), some trees The amount of rain determines whether it is a short, tall, or savanna grassland Adapted to strong winds, infrequent rain, drought Animals: abundant diverse herbivores and their predators Fires and grazing keeps shrubs and trees to a minimum

                                                                       

Fig. 42-17b, p.763

Credit: © Joe McDonald/Visuals Unlimited 301213 Masai Ostrich on African savanna.

Credit: © Joe McDonald/Visuals Unlimited 300241 African Lioness (Panthera leo) and African Elephants, Masai Mara Game Reserve, Kenya.

Credit: © William J. Weber/Visuals Unlimited 228616 Black-Tailed Prairie Dog (Cynomys ludovicianus), head emerging from burrow.

Fig. 42-17a, p.763