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Ecology Definitions.docx

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Western University
Biology 2483A
Hugh Henry

Ecology Definitions Ecology 1. The scientific study of interactions between organisms and their environment 2. The scientific study of interactions that determine the distribution (geographic location) and abundance of organisms Ecological maxims (guiding principles): 1. Organisms interact and are interconnected 2. Everything goes somewhere 3. No population can increase in size forever 4. Finite energy and resources result in trade-offs 5. Organisms evolve 6. Communities and ecosystems change over time 7. Spatial scale matters Ecological hierarchy: Organism < population < community < ecosystem < biosphere Population: Group of individuals of a species that are living and interacting in a particular area. Community: Association of populations of different species in the same area. Biotic: living components Abiotic: physical components Ecosystem: Community of organisms plus the physical environment. Landscapes: Areas with substantial differences, typically including multiple ecosystems. Biosphereall living organisms on Earth plus the environments in which they live. Adaptation: A characteristic that improves survival or reproduction. Natural selection: Individuals with certain adaptations tend to survive and reproduce at a higher rate than other individuals. Ecosystem processes: Producers capture energy from an external source (e.g. the sun) and use it to produce food. Net primary productivity (NPP): Energy captured by producers, minus the amount lost as heat in cellular respiration. Consumers get energy by eating other organisms or their remains How ecosystems work: Energy moves through ecosystems in a single direction onlyit cannot be recycled. But nutrients are continuously recycled from the physical environment to organisms and back againthis is the nutrient cycle. Ecological Experiments: Design and Analysis: 1. Assignments of treatments and control 2. Replication 3. Random assignment of treatments 4. Statistical Analyses (statistical vs. biological significance) The process is iterative and self-correcting. Biological indicators: Amphibians skins are permeable, so they might be early warning to something in the environment. Weather: Current conditionstemperature, precipitation, humidity, cloud cover. Climate: Long-term description of weather, based on averages and variation measured over decades. Greenhouse Gases: Water vapor (H O), 2arbon dioxide (CO ), Met2ane (CH )., 4 Nitrous oxide (N 2). Without greenhouse gases, Earths climate would be about 33C cooler. Uplift: Warm air is less dense than cool air, and it risesthis is called uplift. Three Circulation Cells: Hadley cell (tropic), Ferrell cell (temperate), Polar cell (polar) Prevailing winds: Areas of high and low pressure created by the circulation cells result in air movements. The Coriolis effect: The winds appear to be deflected due to the rotation of the Earth Heat capacity: the number of heat units needed to raise the temperature of a body by one degree. Water has a higher heat capacity than landit can absorb and store more energy without changing temperature. Semi permanent high and low pressure cell: Summer: Air over oceans is cooler and denser, so air subsides and high pressures develop over the oceans. Winter: Air over continents is cooler and denser; high pressure develops over continents. Ocean currents affect climate. The warm Gulf Stream warms the climate of Great Britain and Scandinavia. At the same latitude, Labrador is much cooler because of the cold Labrador Current Downwelling: Where warm tropical surface currents reach polar areas, the water cools, ice forms, the water becomes more saline and more dense and sinks Upwelling is where deep ocean water rises to the surface. Upwelling occurs where prevailing winds blow parallel to a coastline. Surface water flows away from the coast and deeper, colder ocean water rises up to replace it. Upwellings influence coastal climates. Photic zonewhere light penetrates and phytoplankton grow Upwellings bring nutrients from the deep sediments to this zone, thewe areas are the most productive in the open oceans. Maritime climate: Little daily and seasonal variation in temperature, and high humidity. Continental climates: Much greater variation in daily and seasonal temperatures. Annual Seasonal Temperature Variation: Air temperatures over land show greater seasonal variation than those over the oceans Rain shadow: The slope facing prevailing winds (windward) has high precipitation, while the leeward slope gets little precipitation. When air masses meet mountain ranges, they are forced upwards, cooling and releasing precipitation. Albedocapacity of a land surface to reflect solar radiationis influenced by vegetation type, soils, and topography. Loss or change in vegetation can affect climate. Deforestation increases albedo of the land surface: Less absorption of solar radiation and less heating. Lower heat gain is offset by less cooling by evapotranspiration, due to loss of leaf area. Decreased evapotranspiration results in less moisture in the atmosphere and less precipitation. Deforestation in the tropics can lead to a warmer, dryer regional climate. Climatic variation over time: The angle and intensity of the suns rays striking any point on Earth vary as Earth orbits the sun, resulting in seasonal variation in climate. Lake Stratification: In temperate-zone lakes, stratification changes with the seasons. In summer, the warm epilimnion lies over the colder hypolimnion. The thermocline is the zone of transition. Turnover- The complete mixing of a lake. Occurs in spring and fall when water temperature and density become uniform with depth. El Nio Southern Oscillation (ENSO), are longer-scale climate variations that occur every 3 to 8 years and last about 18 months. The positions of high- and low-pressure systems over equatorial Pacific switch, and the trade winds weaken. Upwelling of deep ocean water off the coast of South America ceases, resulting in much lower fish harvests. Long-Term Record of Average Global Temperature- Over the past 500 million years, Earths climate has alternated between warm and cool cycles. Warmer periods are associated with higher concentrations of greenhouse gases Glacial maxima- Earths cool phase- characterized by the formation of glaciers. Interglacial periods- Earths warm phase- characterized by glacial melting These glacialinterglacial cycles occur at frequencies of about 100,000 years. We are currently in an interglacial period; these have lasted about 23,000 years in the past. The last glacial maximum was about 18,000 years ago. Milankovitch cycles- the glacialinterglacial cycles have been explained by regular changes in the shape of Earths orbit and the tilt of its axis. The intensity of solar radiation reaching Earth changes, resulting in climatic change. The shape of Earths orbit changes in 100,000-year cycles. The angle of axis tilt changes in cycles of about 41,000 years. Earths orientation relative to other celestial objects changes in cycles of about 22,000 years Biomes are large-scale biological communities shaped by the physical environment, particularly climate. Dominant plant forms, not taxonomic relationships, categorize biomes. Plant Growth Forms: Deciduous Trees: Moist, seasonally warm/cool or cool/cold on fertile soils or warm seasonally wet/dry. Cacti and Shrubs; succulent stems or leaves: Dry, seasonally hot/cool Needle-leaved evergreen trees: Moist, seasonally warm/cool or cool/cold on infertile soils. Grasses, sedges: Moist, seasonally warm/cool, with fires.
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