Download Ecosystems

Ecosystems Characteris/cs of Ecosystems – cont. •  Every organism occupies an ecological niche •  Stable ecosystems achieve a balance among their popula/ons •  Ecosystems are not permanent, but change over /me Ecosystems Consist of Living and Nonliving Parts •  Abio/c –  Chemical and physical environment •  Bio/c –  Living organisms –  Ecological community •  All interac/ng individuals Energy Flows through Ecosystems •  Food Web –  Interac/ons of organisms •  Trophic Levels –  Photosynthe/c organisms –  Herbivores –  Carnivores –  Decomposers •  Most energy is lost as heat –  10% is transferred MaMer is Recycled by Ecosystems •  Atoms con/nuously cycle Every Organism Occupies an Ecological Niche •  Ecological niche –  Mode of survival •  Each plant/animal fills a niche –  Organisms compete for dominance Stable Ecosystems Achieve a Balance among Their Popula/ons •  Homeostasis –  Balance among popula/ons •  Resources are limited –  Some varia/on in popula/ons –  Overall rela/vely constant Ecosystems Not Permanent -­‐ but Change over Time •  Long /me scale –  Plate tectonics •  Short /me scale –  Glaciers –  Human impact The Law of Unintended Consequences The Law of Unintended Consequences •  It is virtually impossible to change one aspect of a complex system without affec/ng other parts of the systems, oXen in as-­‐yet unpredictable ways. •  Examples: –  Mississippi levees –  Everglades Restora/on Plan –  Lake Victoria The Aral Sea Disaster Science in the Making •  Island biogeography –  Robert MacArthur and Edward Wilson –  Wilson and Daniel Simberloff Threats to the Global Ecosystem and Environment The Problem of Urban Landfills •  Solid Waste –  Nothing is ever thrown away •  Landfills –  Decay slowed enormously •  Response –  Recycling –  Large depositories Different Kinds of Trash in Urban Landfills Technology •  The science of recycling Acid Rain and Urban Air Pollu/on •  Burning introduces chemicals –  Nitrogen oxides, sulfur compounds, hydrocarbons •  Effects –  Air pollu/on •  Produc/on of bad ozone –  Acid rain •  Reduc/on –  Reduce emissions •  Power plants •  Vehicles Los Angeles, CA Acid Rain Acid Rain Destruc/on The Ozone Problem •  Ozone –  Molecule of 3 oxygen atoms –  Absorbs ultraviolet radia/on •  The ozone layer –  Detec/on •  AircraX sampling •  Measure spectral lines from molecule –  Stratosphere •  Highest concentra/on The Ozone Layer The Ozone Problem -­‐ cont. •  The ozone hole –  Concentra/on of ozone reduced •  Yearly occurrence over Antarc/ca –  Linked to chlorofluorocarbons (CFCs) •  Breaks apart O3 molecule •  Dealing with the threat to the ozone layer –  Reduc/on of CFCs The Ozone Problem -­‐ cont. Lower Ozone over Antarc/ca The Greenhouse Effect •  Greenhouse effect –  Traps heat on earth •  Global warming –  Climate change •  3 main points –  CO2 is a greenhouse gas –  Burning fossil fuels increases CO2 –  Average global temperature has significantly increased •  1990s warmest decade The Greenhouse Effect Carbon Dioxide Produc/on Trend Debates about Global Climate Change Debates about Global Climate Change •  Increased CO2 levels –  Responsible for temperature increase? •  World s oceans –  CO2 exchange with atmosphere –  Current circula/on •  Solar energy output –  Varies over /me Debates about Global Climate Change – cont. •  Impact –  Warming of Northern Hemisphere –  Ecological impacts –  Meteorological impacts •  Solu/ons –  Kyoto accord LiMle Ice Age Coastal Flooding The Ongoing Process of Science •  Dealing with the greenhouse effect