Ecology I34.1 Ecologists study how organisms interact with their environment at several levelsSlide 334.2 The biosphere is the total of all of Earth's ecosystemsSlide 534.3 Connection: Environmental problems reveal the limits of the biosphere34.4 Physical and chemical factors influence life in the biosphereSlide 834.6 Regional climate influences the distribution of biological communitiesSlide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 2034.7 Oceans occupy most of Earth's surfaceSlide 22Slide 23Slide 24Slide 25Slide 26Slide 2734.9 Terrestrial biomes reflect regional variations in climateSlide 2934.10 Tropical forests cluster near the equatorSlide 3134.12 Savannas are grasslands with scattered trees34.13 Deserts are defined by their dryness34.14 Spiny shrubs dominate the chaparral34.15 Temperate grasslands include the North American prairie34.16 Deciduous trees dominate temperate forests34.17 Coniferous forests are often dominated by a few species of treesSlide 3834.18 Long, bitter-cold winters characterize the tundraPolar iceSlide 41Ecology ICh 34•Ecologists study environmental interactions at the organism, population, community, and ecosystem levels•Ecology is the scientific study of the interactions of organisms with their environment 34.1 Ecologists study how organisms interact with their environment at several levels Figure 34.1•Ecosystem interactions involve living (biotic) communities and nonliving (abiotic) components –Abiotic components include energy, nutrients, gases, and water •Organisms are affected by their environment–But their presence and activities often change the environment they inhabit•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 ecology34.2 The biosphere is the total of all of Earth's ecosystemsFigure 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 speciesFigure 34.2B•Human activities affect all parts of the biosphere–One example is the widespread use of chemicals34.3 Connection: Environmental problems reveal the limits of the biosphere•The most important abiotic factors that determine the biosphere's structure and dynamics include–solar energy–water–temperature 34.4 Physical and chemical factors influence life in the biosphere•Disturbances such as fires, hurricanes, and volcanic eruptions are also abiotic factors Figure 34.4•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 space34.6 Regional climate influences the distribution of biological communities•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 latitudesFigure 34.6ALow angle ofincoming sunlightSunlight directlyoverheadLow angle ofincoming sunlightAtmosphereNorth Pole60º N30º NTropic ofCancer0º (equator)30º S60º SSouth PoleTropic ofCapricorn•The seasons of the year result from the permanent tilt of the plant on its axis as it orbits the sunFigure 34.6BJUNE SOLSTICE(NorthernHemisphere tiltstoward sun)MARCH EQUINOX(equator facessun directly)DECEMBERSOLSTICE(NorthernHemisphere tiltsaway from sun)SEPTEMBEREQUINOX•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 windsFigure 34.6CAscendingmoist airreleasesmoistureDoldrumsTROPICS30º23.5º0º23.5º30ºDescendingdry airabsorbsmoistureTEMPERATEZONEDescendingdry airabsorbsmoistureTEMPERATEZONETrade winds Trade winds•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 eastFigure 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 CaliforniaFigure 34.6EFresno100ºPacific OceanSanta Barbara 73ºLos Angeles(Airport) 75ºBurbank90ºBakersfield100ºSanta Ana84ºRiverside 96ºSan Bernardino 100ºPalm Springs 106ºDeathValley119º40 milesSan Diego 72ºKey70s (ºF)80s90s100s110s•Landforms, such as mountains, can affect local climateFigure 34.6FPacificOceanCoastRangeWinddirectionCascadeRangeEast•Oceans cover about 75% of the Earth's surface•Light and the availability of nutrients are the major factors that shape aquatic communities 34.7 Oceans occupy most of Earth's surface•Estuaries are productive areas where rivers meet the ocean–The saltiness of estuaries ranges from less than 1% to 3% –They provide nursery areas for oysters, crabs, and many fishes–They are often bordered by extensive coastal wetlandsFigure 34.7A•The intertidal zone is the wetland at the edge of an estuary or ocean, where water meets land –Salt marshes, sand and rocky beaches, and tide pools are part of the intertidal zone –It is often flooded by high tides and then left dry during low tidesFigure 34.7B•Abiotic conditions