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Ecology: The scientific study of
- how organisms affect—and are affected by—other organisms and their environment
- .…the scientific study of distribution and abundance of organisms and their interactions with their biotic (living) and abiotic
- (chemical, physical) environments.
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Environmental Science
how organisms affect—and are affected by—other organisms and their environment.…the scientific study of distribution and abundance of organisms and their interactions with their biotic (living) and abiotic (chemical, physical) environments.
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A population:
A group of individuals of a single species that live in a particular area and interact with one another.
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A community:
An association of populations of different species living in the same area.
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An ecosystem:
A community of organisms plus the physical environment in which they live.
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Biosphere
All the world’s ecosystems comprise the biosphere—all living organisms on Earth plus the environments in which they live.
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Experimental design:
- (1)Replicate—perform each treatment more than once.
- (2) Assign treatments at random.
- (3) Statistical analysis is used to determine significant effects.
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scientific method is a loop. The process is iterative and self-correcting
1. Make observations and ask questions.2. Use previous knowledge or intuition to develop possible answers (hypotheses).3. Evaluate hypotheses by performing experiments, doing observational studies, or using quantitative models.4. Use the results to modify the hypotheses, to pose new questions, or to draw conclusions about the natural world.
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The physical environment....Thus....
- ultimately determines where organisms can live, and the resources that are available to them.
- Thus, understanding the physical environment is key to understanding all ecological phenomena.
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Climate vs weather
- Weather: Current conditions—temperature, precipitation, humidity, cloud cover.
- Climate: Long-term description of weather, based on averages and variation measured over decades.
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Distribution of Solar Energy Winds and ocean currents result from
differences in solar radiation across the surface of Earth.
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Near the equator, the sun’s rays strike Earth’s surface -------------.Toward the poles, the sun’s rays are ------------
- Near the equator, the sun’s rays strike Earth’s surface
- perpendicularly.Toward the poles, the sun’s rays are spread over a larger area and take a longer path through the atmosphere.
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cloud formation depends on
humidity and
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The air creates clouds and then sinks as
cold dry air, possibly forming deserts
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The three cells result in the three major climatic zones in each hemisphere:
Tropical, temperate, and polar zones.
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Subsidence—
the air descends when it cools and forms a high pressure zone at about 30° N and S.
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Equatorial uplift creates a large-scale, three-dimensional pattern of atmospheric circulation known as a
Hadley cell.
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The polar cell
occurs at the North and South Poles—high pressure zones with little precipitation—“polar deserts.”
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Ferrell cells exist at
mid-latitudes
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Areas of high and low pressure created by the circulation cells result in air movements called
Prevailing winds:
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Coriolis Effect
The earth spins, which distorts our earthly view of prevailing wind direction.
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The winds are deflected to the------------- in the Northern Hemisphere and to the -------- in the Southern Hemisphere—the ...
deflected to the right (clockwise) in the Northern Hemisphere and to the left (counterclockwise) in the Southern Hemisphere
Coriolis effect.
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In winter, oceans are warm relative to land creating seasonal areas of high pressure over land Air moves from high pressure to low pressure creating
offshore flowing winds
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-----has a high heat capacity; ---------does not
Water is polar; absorbs heat, resists temperature change Greater annual temperature variation on land
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Upwelling:
deep, cold ocean waters rise to the surface because surface winds push water away from the coast
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Upwellings also bring nutrients from the deep sediments to the ------------—where light penetrates and phytoplankton proliferate.This provides food for zooplankton and their consumers. These areas are the most productive in the open oceans.
photic zone
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Colder climates at higher elevations result from --------------
lower air pressure and density with increasing elevation. As a result, the heat capacity of the air also decreases.
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What causes seasons?
The earth orbits the sun; the earth is tiltedChanges the amount of solar radiation hitting a patch. Creates variation in temperature causing seasons
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Stratification:
- Differences in water temperature with increased depth
- Summer = stratification
- Fall = mixing
- Winter = stratification
- Spring = mixing
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Intertropical Convergence zone (ITCZ):
Area of maximum solar radiation causes changes in precipitation in the tropics
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Seasonal changes in the tropics are
more wet and dry than hot and cold
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Salinity, acidity, and oxygen concentrations are
major determinants of the chemical environment on land and in water.
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Salinity: Salt content; Freshwater Saltwater:
- Freshwater < 1 ppt; Saltwater: ~32 ppt Affect the ability of
- organisms to regulate water balance Influence nutrient availability
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--------------------------- establish global patterns of temperature and precipitation.
Large-scale atmospheric and oceanic circulation patterns
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Global Seasonal Temperature Variation
- Higher seasonal variation in the middle of large continents Little variation in the middle of large oceans
- Sharp clines in variation where land and water meet
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------------can create deserts
High pressure and elevation
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---------------- create zones of increased precipitation
Seasonal variation in onshore flow?
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Regional climates reflect the influence of the distribution of
- oceans and continents, elevation, and vegetation
- Vegetation in turn affects regional climate.
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The Rain-Shadow Effect
- Prevailing winds push moisture up slope where it is dropped leaving little moisture on the other side
- Lush productive forests occur on windward slopes Drought-resistant veg. on leeward side
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Salinization:
- Increasing soil salinity
- Occurs naturally
- Results from agricultural activities
- Affects soil acidity/alkalinity
- Influences distribution and abundanceof animals
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El Nino occurs every
- 3-8 years
- High pressure and low pressure cells in the Pacific switch causing a decrease in upwellings and variation in precipitation
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The North Atlantic Oscillation (NAO)
is a similar atmospheric pressure–ocean current oscillation that affects climate in Europe, northern Asia, and the eastern coast of North America.
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The Pacific Decadal Oscillation (PDO)
affects climate in the North Pacific.
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glacial–interglacial cycles occur every
100,000 years.
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Salmon research led to the discovery of the Pacific Decadal Oscillation (PDO)
20-30 year periods of warm and cool water temperatures in the North Pacific
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Oceans and lakes can become stratified—meaning what
warm surface water on top of colder, denser water results in layers that do not mix.
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These long-term climate oscillations have been explained by regular changes in the shape of Earth’s orbit and the tilt of its axis—called what
Milankovitch cycles.The intensity of solar radiation reaching Earth changes, resulting in climatic change.
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Two aspects of the PDO are particularly significant in the context of ecology:
- 1. The relationship between climate, the functioning of organisms and their growth and reproduction, and population and community processes.
- 2. The time scale of the PDO is long relative to the human life span.
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The physical environment including the --------- affect the --------- of species
-temperature, precipitation, salinity, solar radiation
-distribution and abundance
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--------- dictates climate
Solar radiation, latitude and proximity to oceans and mountains
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Biomes represent areas with
similar physical environments around the world.
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Plants and animals within biomes
have convergent properties
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------------is the most fundamental characteristic of the physical environment.
Climate
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Winds and ocean currents result from
differences in solar radiation across the surface of Earth.
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-------------------establish global patterns of temperature and precipitation.
Large-scale atmospheric and oceanic circulation patterns
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Regional climates reflect the influence of the distribution of
oceans and continents, elevation, and vegetation
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Seasonal and long-term climatic variation are associated with
changes in Earth’s position relative to the sun.
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