GEOG 101 Spring 2014 Lecture 2 Energy Flows, Ecosystems and Global Cycles.

GEOG 101

Spring 2014

Lecture 2

Energy Flows, Ecosystems and Global Cycles

© 2010 Pearson Education Canada

Learning Outcomes:At the end of this lecture, you should be able to:

•Differentiate among the different sources of energy important for Earth’s processes

•Describe photosynthesis and respiration, and explain their importance to living things

•Define ecosystems and evaluate how living and nonliving entities interact in ecosystem-level ecology

•Compare and contrast how water, carbon, nitrogen, and phosphorus cycle through the environment

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Why is Earth Habitable?1. Distance from the sun



2. Oxygen rich atmosphereO2 and O3 shield life from harmful UV raditation



2. Oxygen rich atmosphere

3. Abundant water


Why is Earth Habitable?Results in:

• Moderate radiation intensities

• Surface temperature ~15oC

• All three states of water• vapour• liquid• ice


Water’s properties for life

• Hydrogen bond causes oxygen from one water molecule to be attracted to the hydrogen atoms of another

• Water’s strong cohesion allows nutrients and waste to be transported

• Water absorbs heat with only small changes in its temperature, which stabilizes systems

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Water’s properties for life• Less dense ice floats on liquid water

• Water dissolves other molecules

FIGURE 2.5 (a)

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Earth’s Main Energy Source: The SunSolar energy is responsible for:

1) basic life processes: plant growth and reproduction2) life-support processes: precipitation and soil formation3) life-threatening processes: hurricanes and tornadoes

Available solar energy


Global distribution of solar radiation

Earth’s Main Energy Source: The Sun


Global distribution of moisture

Earth’s Main Energy Source: The Sun


Solar energy is converted to:1) heat2) organic (chemical) compounds

Heat energy accounts for 99% of the solar energy and drives:1) Hydrologic system: cycling of water between

Earth’s reservoirs (atmosphere, ocean, lakes etc.)2) Geochemical (nutrient) system: cycling of chemicals

through water, soil, and air3) Atmospheric circulation: pressure differences due to

differential heating create wind4) Ocean circulation: ocean mixing and currents

Major Energy Systems of Earth


The sun’s energy powers life

• The sun releases electromagnetic radiation, which is a spectrum of energy

- Some is visible light

• Solar energy drives weather and climate, and powers plant growth

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• Photosynthesis = turning light energy from the sun into chemical energy

6CO2 + 6H20 + the sun’s energy C6H12O6 + 6O2

• Respiration

C6H12O6 + 6O2 6CO2 + 6H20 + energy

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The sun’s energy powers life

(sugar)

(sugar)


Earth’s other energy source: Geothermal Energy

FIGURE 2.16. Rabbitkettle Hot Springs, Nahanni National Park Reserve

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Geothermal energy powers Earth’s systems

• Hydrothermal vents = host entire communities that thrive in high temperature and pressure on the ocean floor

- Chemosynthesis = uses chemical bond energy to produce sugar

6CO2 + 6H20 + 3H2S C6H12O6 + 3H2SO4

FIGURE 2.17

2-16(sugar)


• System = a network of relationships among parts, elements or components that interact with and influence one another

- Exchange of energy, matter, or information

-Open systems receives inputs of energy and , matter produces outputs of both

-Closed systems receive input and produce outputs of energy but not matter

- Systems can be challenging to understand and predict

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Systems are networks of relationships


Feedback loops are common in systems.• Feedback loop = a system’s output serves as input to that

same system

• Negative feedback loop = act to reduce an initial change and stabilize a system.

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Feedback loops are common in systems.• Feedback loop = a system’s output serves as input to that

same system

• Positive feedback loop = instead of stabilizing a system, it drives it further toward one extreme or another

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Systems show several defining properties• Homeostasis = a system maintains

constant or stable internal conditions

- Resistance refers to the strength of the system’s tendency to remain constant

- Resilience is a measure of how readily the system will return to its original state once it has been disturbed

• Emergent properties = system characteristics not evident in the components alone

- “The whole is more than the sum of the parts”

5-20FIGURE 5.2

© 2010 Pearson Education Canada5-21

Complex systems: watershed• Environmental entities are complex systems that

interact with each other

• To solve environmental problems, all appropriate systems must be considered


Environmental systems may be perceived in various ways

• Categorizing environmental systems helps make Earth’s great complexity comprehensible

• For example, the earth consists of structural spheres

- Lithosphere = rock and sediment

-Atmosphere = the air

-Hydrosphere = liquid, solid or vapor water

- Biosphere = all the planet’s living organisms and the abiotic portions of the environment

• Boundaries overlap, so the systems interact

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Ecosystems

• Ecosystem = all organisms and nonliving entities that occur and interact in a particular area at the same time

- Includes abiotic and biotic components

- Energy flows and matter cycles among these components

• Biological entities are highly intertwined with chemical and physical entities

- Interactions and feedback loops

Why are healthy ecosystems important?

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Ecosystems are systems of interacting living and nonliving entities• Energy entering the system is processed and

transformed

• Matter is recycled within ecosystem, resulting in outputs such as heat, water flow, and waste products

5-25FIGURE 5.8


Energy is converted to biomass• Primary production = conversion of solar energy to

chemical energy by autotrophs

• Gross primary production (GPP) = assimilation of energy by autotrophs

• Net primary production (NPP) = energy remaining after respiration. Is used to generate biomass

-Available for heterotrophs

• Secondary production = biomass generated by heterotrophs

• Productivity = rate at which ecosystems generate biomass

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Net primary productivityHigh net primary productivity = ecosystems whose plants rapidly convert solar energy to biomass

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FIGURE 5.9


Productivity and Climatic conditions•Three broad categories of climatic limitations:

1) no limitations2) seasonal limitations3) permanent limitations

Net primary productivity


no major limitations

Productivity and Climatic conditions•Three broad categories of climatic limitations:

1) no limitations2) seasonal limitations3) permanent limitations



Terrestrial Productivity Rates:





Wet tropics2200 gC/m2



Midlatitudes (seasonal light and heat)

600-1200 gC/m2Savanna & Mediterranean

(dry season)600-1200 gC/m2




Arctic/Polar(permanent limitations)

5-90 gC/m2

Arid(permanent limitations)

5-90 gC/m2

High Mountains(permanent limitations)

5-90 gC/m2



Net primary productivityOcean Productivity Rates:


Net primary productivityOcean Productivity Rates:

Deep Ocean<250 gC/m2

Coastal Waters6000 gC/m2


Nutrients can limit productivity• Nutrients = elements and

compounds required for survival that are consumed by organisms

• Macronutrients = nutrients required in relative large amounts (Nitrogen, carbon, phosphorus)

• Micronutrients = nutrients needed in smaller amounts Dramatic growth of algae in

water treated with phosphate

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FIGURE 5.10


Housekeeping Items• Before I start with other items, I would like to introduce Sacia

Burton, who is the coordinator of Solutions, the sustainability club on campus. She is also helping to organize a conference on sustainability on March 15th. She’s here to tell about activities that might lend themselves to your action project.

• I appreciate Jeff stepping in in my absence.

• I was having trouble getting e-mails out to the class. Did everyone get the new assignment?

• The web site has been updated, including assignment instructions, except for today’s slides (later today).

• Just a reminder that the due date for project outlines is 2/6.

• Tomorrow the Faculty of Social Science is hosting a welcome back pizza social in Building 355, Room 211 from noon to 2.

• The Career Day event for Geography is next Wednesday (29th) from 10:00 to 11:00 in Room 217.

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• Landscape = larger than an ecosystem and smaller than a biome

• Patches = form the landscape, and are distributed spatially in complex patterns (a mosaic)

Landscape ecologists study geographic areas with multiple ecosystems

5-38FIGURE 5.12

• Conservation biology = study the loss, protection, and restoration of biodiversity


3 minute quiz (2 marks)

Describe and explain two of the three reasons why Earth is habitable.

Name_________


3 minute quiz (2 marks)

Describe and explain two of the three reasons why Earth is habitable.

Answer: (1 mark for each complete answer, half marks for partial answers)

•Distance from the Sun, results in moderate surface temperature

•Oxygen rich atmosphere, provides protection from UV radiation

•Abundant water, essential for life and climatic processes

Name_________


Remote sensing and GIS are important tools

• Remote sensing technologies allow scientists to create a complete picture of the landscape

• Geographic information system (GIS) = computer software used in landscape ecology research

• Can analyze how elements within the landscape are arranged to help make planning and land-use decisions

5-41FIGURE 5.13


Nutrients circulate via biogeochemical cycles

• Nutrient (biogeochemical) cycle = the movement of nutrients through ecosystems

- Atmosphere, hydrosphere, lithosphere, and biosphere

• Reservoirs = where nutrients reside for varying amounts of time

• Sources = reservoirs that release more nutrients than they accept

• Sinks = accept more nutrients than they release

• Flux = movement of nutrients into or out of reservoirs, which change over time and are influenced by human activities

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The rock cycle (Lithosphere)• Rock cycle = The heating, melting, cooling, breaking and

reassembling of rocks and minerals

• Rocks help determine soil chemistry, which influences ecosystems

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Plate tectonics shapes Earth’s geography

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FIGURE 5.6

• Plate tectonics = process that underlies earthquakes and volcanoes and that determines the geography of the Earth’s surface


• Plate tectonics leads to:

-Volcanic outgassing: releases carbon dioxide (CO2), water vapour (H2O) and other gasses

-Weathering: releases minerals

Plate tectonics shapes Earth’s geography


The hydrologic cycle

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FIGURE 5.15


The hydrologic cycle influences all other cycles• Water is essential for biochemical reactions and is

involved in nearly every environmental system

• Oceans are the main reservoir (97% of water)

• Precipitation = condensation of water vapor as rain or snow

• Evaporation = water moves from aquatic and land systems to air

• Transpiration = release of water vapor by plants

• Evapotranspiration = the total flux of water vapor from the the Earth’s surface to the atmosphere

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Groundwater

• Aquifers = underground reservoirs of porous rock and soil that hold groundwater

-Groundwater = water found underground beneath layers of soil

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Figure 9.16


Groundwater

-Water table = the upper limit of groundwater held in an aquifer

-Water may be ancient (thousands of years old)

• Lakes and streams where the water table reaches the surface5-49

Figure 9.16


Our impacts on the hydrologic cycle are extensive• Damming rivers increases evaporation and infiltration

• Altering the surface and vegetation increases runoff and erosion

• Spreading water on agricultural fields depletes rivers, lakes and streams

• Removing forests and vegetation reduces transpiration and lowers water tables

• Emitting pollutants changes the nature of precipitation

• Overdrawing groundwater for drinking, irrigation, and industrial use

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Your water

• Are you aware of any water shortages or conflicts over water use in your region?

• What is the quality of your water, and what pollution threats does it face?

• Given your knowledge of the hydrologic cycle, what solutions would you propose for water problems in your region?

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weighing

the issues


The carbon cycle

5-52FIGURE 5.16

• Carbon is found in carbohydrates, fats, proteins, bones

• Photosynthesis moves carbon from the air to organisms

• Respiration returns carbon to the air and oceans

• Decomposition returns carbon to the sediment, the largest active reservoir of carbon

• The world’s oceans are the second largest reservoir of carbon


The carbon cycle

Sinks: 203 GtC/y1) Photosynthesis 2) Solubility in water

Sources: 207 GtC/y1) Respiration2) Volcanic3) Ocean outgassing4) Fossil fuels !!!

Net balance: 4 GtC added to the Atmosphere annually


Atmospheric concentration:396 ppm (parts per million)

Higher than the past 650,000 years

CO2 is a greenhouse gas

Is the main cause of global warming

Humans affect the carbon cycle


The nitrogen cycle

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• Nitrogen is 78% of our atmosphere but N2 gas is inert (not a usable form)

• Nitrogen fixation = Nitrogen gas is fixed (made into ammonia) by nitrogen-fixing bacteria and lightning

-Usable form (ammonium ions)


Nitrification and denitrification

• Nitrification = bacteria that convert ammonium ions first into nitrite ions then into nitrate ions

- Plants can take up these ions

-Animals obtain nitrogen by eating plants or other animals

• Denitrifying bacteria = convert nitrates in soil or water to gaseous nitrogen, releasing it back into the atmosphere

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Humans affect the nitrogen cycle• Over-fertilization, commercial, solid and liquid animal

wastes

- Industrial fixation = 50% of global nitrogen fixation

• This imbalance is most obvious in waterways that tend to collect nitrogen as part of the hydrologic process

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The phosphorus cycle involves mainly lithosphere and ocean

• Phosphorus is a key component of cell membranes & DNA

-Most phosphorus is within rocks and is released by weathering

• With naturally low environmental concentrations, phosphorus is a limiting factor for plant growth


We affect the phosphorus cycle

• Mining rocks for fertilizer moves phosphorus from rock and soil to water systems

-Wastewater discharge also releases phosphorus

• Runoff containing phosphorus causes eutrophication of aquatic systems

• Household detergents may contain phosphorus

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The addition of Nitrogen or Phosphorus can accelerate plant growthin aquatic systems that leads to oxygen depletion and toxic conditions

Eutrophication


Eutrophication• The process of nutrient over-enrichment, blooms of

algae, increased production of organic matter, and ecosystem degradation

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FIGURE 5.19


Gulf Coast Dead Zone

Eutrophication


Eutrophication


Summary• The sun is the main energy source for Earth and enables

life to flourish.

• Photosynthesis uses carbon dioxide, water and sunlight to produce oxygen and simple sugars while respiration is the opposite and consumes oxygen, releases carbon dioxide

• Understanding biogeochemical cycles is crucial because human activities are changing the way cycles function

• We can learn about sustainability from natural systems. Unperturbed ecosystems use renewable solar energy, recycle nutrients, and are stabilized by negative feedback loops

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GEOG 101 Spring 2014 Lecture 2 Energy Flows, Ecosystems and Global Cycles.

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