Ecology and Biomes

• Chapter concentrates on ecology and biomes.

Ecology Defined

• Ecology studies the interactions between organisms and their environment.
• Biotic interactions are those among living organisms.
• Abiotic interactions are those between organisms and their non-living environment.
• Environmental science is the application of ecology to real-world problems.

Scales of Ecology

• Ecology is studied at different scales, including organismal, population, community, and ecosystem ecology.
• Organismal ecology has 2 subdisciplines.
• Physiological ecology looks at how organisms are adapted to their environment physiologically.
• Behavioral ecology studies how an individual organism's behavior contributes to its survival and reproduction.
• Population ecology focuses on populations of organisms.
• Factors affecting population growth, density, and size are investigated.
• Species interactions such as predation, competition, and parasitism are also studied.
• Community ecology studies the interactions between populations of different species and how they form communities.
• It explores why some areas have high species richness while others are species-poor.
• Community ecology also studies succession, which is how species composition and community structure change over time.
• Ecosystems ecology studies the flow of energy and nutrients among organisms within a community and between organisms and the environment.
• Food chains show the transfer of energy and nutrients.
• Levels in food chains are called trophic levels.
• Food chains interconnect to form food webs.

Ecological Methods: Oak Winter Moth Example

• Accidentally introduced to the USA and is a pest in apple orchards.
• First step in controlling this pest is to outline a web of interactions affecting the locust population size.
• Factors include temperature, rainfall, wind, soil pH, predators, parasites, grazers and plant quality.
• Hypothesis testing then follows a 5 step process.
• The 5 steps are: 1. Observations, 2. Hypothesis formation, 3. Experimentation, 4. Data analysis, 5. Acceptance or rejection of hypothesis.

Testing Correlations

• Moth numbers are related to levels of the parasite Cyzenis albicans.
• A correlation exists between moth numbers and parasite numbers.
• A strong correlation is implied when correlation numbers are close to the line of best fit.
• A statistical test can help determine if the relationship is real, resulting in a significant correlation if so.
• While graphs may imply a correlation that does not always equal causation.
• In an experiment, predators are removed from moth populations. A control group is also observed for changes.
• Any differences between experimental and control groups should be due to the experiment.
• The experiment should be repeated to confirm the results.
• Without predators, them number of moths is more than double that with predators.
• The parasitic fly, C. albicans is useful for biological control.

Environmental Factors and Distribution

• Distribution pattern and abundance are limited by physical features of the environment.
• Key factors are temperature, wind, availability of water and light, salinity, and pH.

Temperature Effects

• A key factor in organism distribution.
• Influences biological processes.
• Most organisms can't precisely regulate body temperature.
• Coral reef organisms thrive in warm water.
• Cactus distribution is limited to temperatures that do not remain below freezing for more than one night.
• Endothermic animal ranges are also affected by temperature.
• Eastern phoebe limits are related to energy demands of cold temperatures.
• High temperatures can cause corals to expel algae.
• Giant sequoias depend on fire to enhance seed release.

Greenhouse Effect

• Solar radiation passes through the atmosphere and heats the Earth's surface.
• Energy radiated back into atmosphere is absorbed by atmospheric gases.
• These gases include carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons.
• Greenhouse effect causes reradiation back to the Earth increasing surface temperature.
• The amount of all greenhouse gases in the atmosphere have increased since the industrial revolution.
• Carbon dioxide has a lower warming potential but is higher in concentration.
• Global climate changes cause rapid normal evolutionary processes.
• Climate zones are shifting faster than trees can migrate via seed dispersal.

Further climate factors

• Wind can amplify temperature, increasing heat loss through evaporation.
• The effect of wind also increases oceanic wave action.

Water Availability

• Plants in swamps thrive when flooded.
• Roots of plants on sand dunes access water.
• Rainfall governs buffalo density by controlling grass productivity in the Serengeti.

Light Factors

• Light needs vary among plants of different species.
• Three photosynthetic pathways (C3, C4, and CAM) adapt plants to light intensity and water availability.
• Aquatic environments filter light, preventing photosynthesis at depths greater than 100m.
• Red algae have pigments enabling them to use blue-green light at greater depths.

Salt Concentration

• Freshwater fish maintain internal salt concentration and constantly take in water.
• Marine fish compensate for salt water and excrete salt.
• Watering in arid areas can cause salt concentration due to evaporation.
• Halophytes are plants that tolerate higher salt concentrations.
• Halophytes also have glands that excrete salt.

pH Factors

• Normal rainwater is pH 5.6.
• Carbonic acid makes rainwater slightly acidic.
• Nutrients are most available to plants at pH 6.5.
• pH less than 5.2 prevents nutrients from working.
• Chalk-limestone areas have more flora than acidic soils.
• Optimal pH for freshwater fish is neutral.
• Acid increases toxic metal amounts.
• Acid rain is pH less than 5.6 caused by burning fossil fuels.
• This causes rivers-lakes to become acidic.

Climate and Habitats

• Climate determines temperature, precipitation, wind, and light within a region.
• Climate determines the different biomes.

Atmospheric Circulation

• Temperature differences occur due to latitudinal variations in incoming solar radiation.
• The sun's rays hit the Earth at an oblique angle which cause spreading in higher latitudes.
• The amount of solar radiation increases generally.
• Atmosphere is affected by precipitation that creates uniform temperatures.
• Global patterns of atmospheric circulation and precipitation are influenced by solar energy.
• Hadley proposed a model based on one convection cell in each hemisphere.
• Heat at the equator causes air to travel north and south toward poles.
• Air cools and falls, flowing back to the equator.
• Coriolis effect adds in effect of Earth's rotation that deflects surface flow westward.
• there are 3 cells in each hemisphere
• The Hadley cell nearest the equator.
• The Polar cell is nearest the poles.
• And the Ferrell cell, in between the previous stated cells.
• Major biomes are determined by temperature and wind patterns.

Elevation and Rain Shadow

• Warm air rises through adiabatic cooling leading to a 10°C drop for every 1,000m upwards.
• Rain shadow occurs as warm, moist air flows up a mountain.
• This warm and moist hair cools and releases precipitation.
• Leeward side allows drier air to descend forming area with little precipitation.
• Landmasses effect wind in coastal areas by creating sea breezes during the day.
• This warms the land pulling in ocean wind.
• Cooler oceans create offshore breezes at night as Land quickly cools.
• Oceans moderate coastal and island temperatures.
• Winds and the Earth's rotation causes ocean currents.

Terrestrial Biomes

• Classified according to physical factors of average annual precipitation and temperature.
• There are 10 biomes;
• Tropical rain forest.
• Tropical deciduous forest.
• Temperate rain forest.
• Temperate deciduous forest.
• Temperate coniferous forest (taiga).
• Tropical grassland (savanna).
• Temperate grassland (prairie).
• Hot desert.
• Cold desert.
• Tundra.
• Also mountain ranges.
• Climate diagrams show the average temperature and precipitation.
• Altitude causes habitat variation.

Aquatic Biomes

• There are 6 aquatic biomes distinguished by differences in salinity, oxygen content, depth, current strength and light availability.
• Freshwater habitats divided into lentic (standing water) and lotic (running water) habitats.
• Intertidal (Coastal) Areas have salty water, high oxygen count, shallow depth, high strength of current and high light.
• Coral Reefs have salty water, high oxygen count, shallow depth, moderate to low strength of current and high light.
• Open Oceans are salty, have variable oxygen content, large depths, high stream strength and variable light availability.
• Ocean deserts are low density and contain higher levels of nutrients to provide energy.
• Deep ocean vent communities rely on nutrients for energy.
• Fresh water lakes have variable depths and a high oxygen count.
• Rivers vary depending on light availability, and have a mostly shallow depth.
• Wetlands tend to very.