Article Summaries for BIO120

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Paul Thompson

1introduction to the basic drivers of climateClimate is the long term prevailing weather determined by temperature and precipitationLargest determinant of life in a regionLong term changes in climate are due to changes in intensity and distribution of solar radiation Sunlight and Atmospheric CiruclationsSunlight intensity is key in climateenergy from the sun is not evenly distributed throughout earth Higher latitudes receive less solar energyThe different orientation of the earth as it orbits the sun creates seasons Tropics have minor temperature changestheir seasons are characterized by the presence or absence of rainBoth hemispheres have equal solar input during spring and fall equinoxThe sun is most intense at the equatorthis warms up the air making it less dense and causes it to riseThe warm arm rising in the tropics is wet as it rises and cools the water condenses and falls as rainSunlight also creates winds that push the now dry tropical air away from the equatorDescends at 30 degrees north or south and absorbs moisture from the ground creating dry areasAt 60 degrees the air rises again and precipitatesSome of the cold dry rising air flows to the poles absorbs moisture and create cold polar climates Oceanic CurrentsWind is also generated through earths rotation east and westward windsWarm tropical water carry heat on the east side of continents to the poles and cold water is forced down the west side from the polesBrings temperate climates to areas away from tropicsMelted ice caps flow deep underwater towards the equatorOceanic currents depend on earths rotation and temperature differences between the poles and the equationCurrent flow varies with depthWind and ocean currents redistribute heat60 by atmospheric circulation 40 by ocean currentsHigh heat capacity of water leads to the moderating effectalong with heat redistribution of heat by currents creates mild climatesCoastal regions are wet continental regions are dry They lack bodies of water to recharge moistureEg mountain ranges force air to rise cool and precipitate on the windward sideConsequently the dry air descends on the leeward side and absorbs ground moistureCreates a dry and arid rain shadowMicroclimates are the variation in physical structure of an areaDue to different ground colour vegetation etcEl Nino usually winds blow strong from east to west carrying with it the warm surface water This warm water piles around the west pacific and the cold water rises in the east to replace it As the winds decrease the warm water starts pooling around the east as well which then decreases the winds even more positive feedbackConsequences precipitation in the eastern pacificFlooding in north and south America drought in Australia Indonesia and AfricaTypical arid regions become wet and experience a population boom in AmericasCauses an increase in diseases and virusesMarine life cold water rising brings nutrients as well with El Nino the nutrient supply is cut Phytoplankton declines and marine populations decline2Terrestrial BiomesBiomes differ most in vegetation and are defined by temperature and rainfallWarm and wet climatescool and dry climates Decrease in height density and species diversity of plantsRaunkiaer classified life form based on the perannating organ location on the plantClimate regions are classified into biomes Tropicalcentered around equatorlittle seasonal variationhigh rainfall biodiversity and productivitypoor phanerotype dominated soilshigh decomposition rates due to heat and moisture and mycorrhizae containsof terrestrial species on Earth Savannalower rainfall longer dry seasonsdominated by grasses and small treestransition from tropical forests to deserts repetitive firesreleases nutrients in dead plantdecomposition is fastdung beetles break down animal droppingslarge herbivore diversityDesertsbetween 15 and 30 degrees latitudeslow precipitation and productivitydifferent types hot cold high elevation rainshadow desertsperennial shrubs dominate annuals survive dry periods as seeds Grasslandoccur in the interior of continentstemperature varies largely over seasonshot summers and cold winterssummerpeak precipitationtransition into deciduous on wet side and deserts on dry sidefire droughts and grazing are the selective forces on plantsworlds largest terrestrial animals can be found Temperatehigh precipitation high litter production high biodiversity Deciduouscool winters warm summerstrees that drop their leaves Mediterraneandivided into 5 separate regionshot dry summers cool moist wintersproductivity decreases after 1020 years due to collection of litter and biomassfire recycles nutrientslots of therophytes plants that survive unfavourable conditions as seeds Northern Coniferous needle leaved drought tolerant evergreen treeslong cold winters short cool summers precipitates mostly in summerlow biodiversity and productivity permafrost trees have shallow root systems dependent on mycorrhizaeslow decompositionmidhight latitudes Tundrabelow freezing temperaturesmarshylots of mosses and lichens 60 hemicryptophytesbudding near surfaceanimals have extended hibernation or migrate3Physiological EcologyTemperature and water availability significantly affects physiological ecology how organisms are physiologically adapted to their environments4Physiological Optima and Critical LimitsDistribution limits are dependent on biotic and abiotic factorsOrganisms have an optimal environmental range where fitness is optimized and critical limits where they can only survive for short periods of time Thermal Performance Curves
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