The biosphere is the total of all of Earth's ecosystems The global ecosystem is called the biosphere It is the sum of all the Earth's ecosystems. The biosphere is the most complex level in ecology. Figure 34.2A

The biosphere is self-contained except for energy obtained from the sun and heat lost to space. Patchiness characterizes the biosphere. Patchiness occurs in the distribution of deserts, grasslands, forests, and lakes. Each habitat has a unique community of species. Figure 34.2B

Connection: Environmental problems reveal the limits of the biosphere Human activities affect all parts of the biosphere. One example is the widespread use of chemicals. Mining Logging Pollution Construction and land clearing

Physical and chemical factors influence life in the biosphere The most important factors that determine the biosphere's structure and dynamics include: solar energy water temperature

Disturbances such as fires, hurricanes, and volcanic eruptions are abiotic or natural occurrences that can alter the earths surface. Figure 34.4

Natural selection adapts organisms to abiotic and biotic factors. Organisms are adapted to abiotic and biotic factors by natural selection The presence and success of a species in a particular place depends upon its ability to adapt. Natural selection adapts organisms to abiotic and biotic factors. Biotic factors include predation and competition. Figure 34.5

Regional climate influences the distribution of biological communities Climate often determines the distribution of communities. Earth's global climate patterns are largely determined by the input of solar energy and the planet's movement in space.

Most climatic variations are due to the uneven heating of Earth's surface. This is a result of the variation in solar radiation at different latitudes. North Pole 60º N Low angle of incoming sunlight 30 º N Tropic of Cancer Sunlight directly overhead 0º (equator) Tropic of Capricorn 30º S Low angle of incoming sunlight 60º S Atmosphere South Pole Figure 34.6A

The seasons of the year result from the permanent tilt of the planet on its axis as it orbits the sun. MARCH EQUINOX (equator faces sun directly) JUNE SOLSTICE (Northern Hemisphere tilts toward sun) DECEMBER SOLSTICE (Northern Hemisphere tilts away from sun) SEPTEMBER EQUINOX Figure 34.6B

The tropics experience the greatest annual input and least seasonal variation in solar radiation. The direct intense solar radiation near the equator has an impact on the global patterns of rainfall and winds.

moist air releases moisture Low High High Ascending moist air releases moisture Descending dry air absorbs moisture Descending dry air absorbs moisture Trade winds Trade winds Doldrums 0º 23.5º 23.5º 30º 30º TROPICS TEMPERATE ZONE TEMPERATE ZONE Figure 34.6C

Warm, moist air at the equator rises. As the air rises, it cools and releases much of its water content. This results in the abundant precipitation typical of most tropical regions. After losing their moisture over equatorial zones, high altitude air masses spread away from the equator.

They cool and descend again at latitudes of about 30° north and south. This explains the locations of the world's great deserts. As the dry air descends, some of it spreads back toward the equator. This creates the cooling trade winds that dominate the tropics.

Temperate zones are located between the tropics and the Arctic Circle in the north and the Antarctic Circle in the south. They have seasonal variations in climate. The temperatures are more moderate than in the tropic or polar regions.

Prevailing winds result from the combined effects of the rising and falling of air masses and Earth's rotation In the tropics, Earth's rapidly moving surface deflects vertically circulating air, making the winds blow from east to west. In temperate zones, the slower-moving surface produces the westerlies, winds that blow from west to east. Figure 34.6D

Ocean currents have a profound effect on regional climates by warming or cooling coastal areas. They are created by winds, planet rotation, unequal heating of surface waters, and the locations and shapes of continents.

Local high temperatures for August 6, 2000, in Southern California: Notice the temperature difference at the coast and inland. Fresno 100º 40 miles Death Valley 119º Bakersfield 100º Pacific Ocean Burbank 90º Santa Barbara 73º San Bernardino 100º Key Riverside 96º Los Angeles (Airport) 75º 70s (ºF) Santa Ana 84º Palm Springs 106º 80s 90s 100s 110s San Diego 72º Figure 34.6E

Landforms, such as mountains, can affect local climate Landforms, such as mountains, can affect local climate. This is called adiabatic heating and cooling. This process is the main reason for the deserts in the southwestern United States. East Wind direction Pacific Ocean Cascade Range Coast Range Figure 34.6F

The End