19-ch34-ecology - Chapter 34 – The Biosphere Oikos = “home” ecology ecology – study of interactions of of interactions of organisms(biota

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Unformatted text preview: Chapter 34 – The Biosphere Oikos = “home” ecology ecology – study of interactions of of interactions of organisms (biota) with: 1) each other & 2) their physical environment biotic components – organisms components that are part of environment abiotic components – nonliving chemical & physical factors Abiotic Abiotic factors influence distribution of species • sunlight – food webs are based on solar energy input • water – essential to all life (& maintain water balance) • temperature – affects chemistry; 1) metabolic rate 2) molecular structure; normal limits for organisms: 0-45ºC • wind – increases water (& heat) loss; knocks down trees • disturbances – (unpredictable, but sometimes periodic) but sometimes periodic) destruction of organisms; fire, storms, volcanoes, anthropogenic (human) disturbances -- habitat destruction • rocks & soil – physical structure, chemical composition Regional Regional climate influences distribution of biological communities orbit of earth around the sun changes angle of of earth around the sun changes angle of sunlight (causing seasons) temperate zones – region between latitude 23 23.5ºN (Cancer) & 66.3ºN (Arctic Circle); (C 66 (A Ci between 23.5ºS (Capricorn) & 66.33ºS (Antarctic Circle) Regional Regional climate influences distribution of biological communities tropics – region between lattitude 23.5º N (Cancer) & 23.5 º S (Capricorn) warm equatorial air rises; cools & releases water (= more rain) biodiversity highest in tropical rainforest; why? why? prevailing winds – caused by rising (warm) & falling (cool) air masses rotation fastest at equator; winds blow east to west; bl rotation slower in temperate zones; westerlies ocean currents determined by: prevailing winds + rotation + unequal heating of water + location, shapes of continents Oceans Oceans & landforms moderate local climate • coastal air temperature is mild & constant (compared to inland) • air temperature declines by 6º C for every 1000 m elevation • rain falls on the windward side of falls on the windward of the mountain; lee side is dry Oceans Oceans & landforms moderate local climate Oceans Oceans occupy most of Earth’s surface aquatic biomes are affected by amount of light, distance from shore intertidal zone – shoreline habitat pelagic zone – open water habitat zone water habitat benthic zone – sea floor photic zone – sunlight penetrates surface, allowing photosynthesis only rarely includes benthic zone rarely includes benthic zone (continental shelf; coral reef) aphotic zone – no photosynthesis Jeremy Jackson: How we wrecked our oceans http://www.ted.com/talks/jeremy_jackson.html Wetlands Wetlands are transitions between aquatic & terrestrial habitat estuary – where freshwater river mouth meets ocean Poisoned Waters min 25:00-32:45 25:00- - enriched in nutrients - salinity gradient - often abused development, landfill http://www.pbs.org/wgbh/pages/frontline/poisonedwaters/view Freshwater Freshwater biomes: lakes, ponds oligotrophic – low nutrient levels; clear water eutrophic – high nutrient levels; productive system Freshwater Freshwater biomes: lakes, ponds, rivers, streams, wetlands eutrophic lakes – high lakes nutrient levels; productive system agricultural fertilizers can make systems too productive (eutrophication), phytoplankton “blooms” may result in fish kills in fish kills Patchiness Patchiness exists on global (& local) scales biosphere – global ecosystem; entire portion of Earth inhabited ecosystem; entire portion of Earth inhabited by life; sum of all the planet's ecosystems biome – one of the world's major ecosystems, classified of the world major ecosystems classified according to the predominant vegetation & characterized by adaptations of organisms to that particular environment ecotone – region of intergradation between biomes Terrestrial Terrestrial biomes reflect regional variations in climate Tropical Tropical forests cluster near the equator - rainfall 200-400 cm/yr - thorny shrubs, deciduous trees - complexity & biodiversity - vertical stratification - poor soils (rapid nutrient cycling) Savannas are grasslands with scattered trees - rainfall 30-50 cm/yr - grasses, scattered trees scattered trees - fires prevent forestation - relatively simple in structure - seasonal migration of grazers As As fences cut off migrations, hoofed species decline http://www.npr.org/templates/player/mediaPlayer.html?action=1&t=1&islist=false&id=105165068&m=105173858 http://channel.nationalgeographic.com/channel/great-migrations-animals-wildebeest http://channel.nationalgeographic.com/channel/great-migrations?source=banner_sangc_151 “As if we all knew where we were going.” Deserts Deserts are defined by their dryness - rainfall < 30 cm/yr - descending dry air pattern - temperature fluctuations - cycles of growth (with rainfall) of growth (with rainfall) - deep-rooted shrubs, cacti, succulent plants Spiny shrubs dominate the chapparal - mild, rainy winter; hot dry summer - moderated by ocean currents - periodic fires fires - perennial shrubs, w/ annual plants Temperate Temperate grasslands include the North American prairie - treeless except along rivers - cold winters - periodic drought, fires - shortgrass or tallgrass prairies shortgrass or tallgrass prairies - often converted to agricultural use Broadleaf trees dominate temperate forests - enough moisture for large trees - deciduous trees (lose leaves) - seasonal variation in temperature variation in temperature - leaf litter (slow nutrient cycling) http://www.npr.org/templates/story/story.php?storyId=114288700 Coniferous Coniferous forests are often dominated by a few species of trees - expansive northern “taiga” - long, cold winters; wet summers - nutrient poor, acidic soil - snow insulates soil insulates soil - low diversity of tree species Long, dark, cold winters characterize the tundra - northern limit of plant growth - low rainfall / saturated soil - dwarf shrubs, grasses, mosses shrubs, grasses, mosses - permafrost (frozen soil layer) Destroying rainforest for economic gain is like burning burning a Renaissance painting to cook a meal. E.O. Wilson http://www.ecologyfund.com http://www.therainforestsite.com Click to save the rainforest and other habitat other habitat for free! ...
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This note was uploaded on 12/07/2011 for the course BIO 2 taught by Professor Poenie during the Fall '08 term at University of Texas at Austin.

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