© 2010 pearson education canada 3 environmental systems and ecosystem ecology powerpoint ® slides...

© 2010 Pearson Education Canada

3

Environmental Systems and Ecosystem Ecology

PowerPoint® Slides prepared by Stephen Turnbull

Copyright © 2013 Pearson Canada Inc.

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Housekeeping Items• The deadline for the extra-credit reflections piece

on the video Home by Yann Arthus-Bertrand I didn’t make explicit is Wednesday, but I will accept electronic submissions up through Thursday.

• I am also extending the deadline for the assignment outlines to Monday, October 7th. As I will be away next week, if you have any questions talk to me this week! For those of you joining an action group for one of your assignments, if you contact info let me know.

• The group I mentioned before, Solutions, is having today at 4 pm in the Spruce group viewing room on the main floor of the library.

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Upon completing this chapter, you will be able to:

• Describe the fundamental properties of environmental systems and the importance of linkages among environmental systems and processes

• Define ecosystem and discuss how living and nonliving entities interact in ecosystems

• Outline the fundamentals of landscape ecology, GIS, and the use of modelling in environmental science

• Assess ecosystem services and their benefits to us

• Summarize the main features of global water, carbon, nitrogen, and phosphorus cycles

• Explain how human activity is affecting biogeochemical cycles

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Central Case: The Plight of the St. Lawrence Belugas• Decreasing population due to GI cancer from pollutants

(PAHs from fossil fuels)

• Biomagnification of contaminants through food chain

• PAHs come from as far away as the Golden Horseshoe in Ontario

• Agricultural development also leads to hypoxia and eutrophication

• Beluga is classified as “threatened” by Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and is an indicator of the Great Lakes – St. Lawrence ecosystem

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Earth’s Environmental Systems

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• 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 receive inputs of energy and matter, and produce outputs of both

- Closed systems (i.e. Earth) receive input and produce outputs of energy but not matter

- hard to understand and predict

Systems are networks of relationships

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Feedbacks are common in environmental systems

• Feedback loop = a system’s output serves as input to that same system

• Negative feedback loop = output that results from a system moving in one direction acts as input that moves the system in the other direction.

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

• Dynamic equilibrium = system processes move in opposing directions at equivalent rates, balancing their effects

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Negative and positive feedback loops

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Homeostasis is a state of balance•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

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A whole may be more than the sum of its parts

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

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

- Can’t predict biological behaviour on the basis of chemistry

- Can’t predict the behaviour of humans on the basis of other living things

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Complex systems have multiple subsystems• Environmental entities are complex systems that

interact with each other

- For example, river systems consist of hundreds of smaller tributary subsystems

• To solve environmental problems, all appropriate systems must be considered, something that tends not to happen. Examples?

• We will see later what happens when one adopts a silo or “rifle barrel” approach to environmental problems.

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Complex systems and subsystems: watershed

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Environmental systems may be perceived in various ways

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

• For example, the earth consists of structural spheres

- Geosphere = 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

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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

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Ecosystems are systems of interacting biotic and abiotic components

• Energy entering the system is processed and transformed

• Matter is recycled within ecosystem, resulting in outputs such as heat, water flow, and waste products (often in the form of nutrients)

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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, and 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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High net primary productivity = ecosystems whose plants rapidly convert solar energy to biomass

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• Variation in net primary productivity among ecosystems and biomes results in geographic patterns of variation across the globe



Nutrient availability limits 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, such as iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc and molybdenum.

Dramatic growth of algae in water treated with phosphate

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Ecosystems are integrated spatially

• Ecosystems vary greatly in size

• The term “ecosystem” is most often applied to self-contained systems of moderate geographic extent

• Adjacent ecosystems may share components and interact

• Ecotones = transitional zones between two ecosystems in which elements of different ecosystems mix. Examples?

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Ecosystems Where You Live

• Think about the area where you live. How would you describe the ecosystems?

• How do these systems interact with one another?

• If an ecosystem is greatly disturbed (say, a wetland, forest and bluff complex replaced by a housing development) what impacts might that have on the system and others nearby?

weighing

the issues

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

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

Landscape ecologists study geographic patterns

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Land cover surroundingMadison, WI



Landscape ecologists study geographic patterns

• Metapopulation = a network of subpopulations

- Most members stay within patches but may move among patches or mate with those of other patches

- Individuals in small patches risk extinction

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

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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

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Models help scientists understand complex systems• Model = a simplified representation of a complex natural

process, designed to help us understand how the process occurs and to make predictions

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What Mother Nature Does for Free



Ecosystem Services

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Biogeochemical Cycles

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Nutrients and other materials move in biogeochemical cycles

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

- Atmosphere, hydrosphere, lithosphere, and biosphere

• Pools (reservoirs) = where nutrients reside for varying amounts of time

• Flux = movement of nutrients among pools, which change over time and are influenced by human activities

• Sources = pools that release more nutrients than they accept

• Sinks = accept more nutrients than they release

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Properties of reservoirs

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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)

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

• Transpiration = release of water vapor by plants

• Precipitation = condensation of water vapor as rain or snow

• Infiltration= seepage into groundwater tables/ aquifers

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The hydrologic cycle

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• Aquifers = underground reservoirs of sponge-like regions of rock and soil that hold groundwater

- Groundwater = water found underground beneath layers of soil

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

- Water may be ancient (thousands of years old)

• Groundwater becomes exposed to the air where the water table reaches the surface often in the form of a spring

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The hydrologic cycle influences all other cycles (cont’d)



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

• The most threatening impact is overdrawing groundwater for drinking, irrigation, and industrial use

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The carbon cycle circulates a vital organic nutrient

• 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 reservoir of carbon

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

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The carbon cycle

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Humans affect the carbon cycle• Burning fossil fuels moves carbon from the ground to the

air (from ‘source’ to ‘sink’)

• Cutting forests and burning fields moves carbon from organisms to the air

• Today’s atmospheric carbon dioxide reservoir is the largest in the past 650,000 years

- The driving force behind climate change

• The missing carbon sink: 1-2 billion metric tons of carbon are unaccounted for

- It may be the plants or soils of northern temperate and boreal forests

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The nitrogen cycle involves specialized bacteria

• 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 on the roots of certain plants (legumes)

- Usable form (ammonium ions) for plants

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FIGURE 5.18



The nitrogen cycle

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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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We have greatly influenced the nitrogen cycle

• Haber-Bosch process = synthetic production of fertilizers by combining nitrogen and hydrogen to synthesize ammonia

- Humans are fixing as much nitrogen as nature does!

• Increased emissions of nitrogen-containing greenhouse gases

• Calcium and potassium in soil washed out by fertilizers

• Acidified water and soils

• Increased transfer from rivers to oceans

• Reduced biodiversity of plants adapted to low-nitrogen soils

• Changed estuaries and coastal ecosystems and fisheries

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

algae, increased production of organic matter, and ecosystem degradation

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Nitrogen Pollution and Its Financial Impacts

weighing

the issues

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The phosphorus cycle involves mainly geosphere and ocean

• Phosphorus is a key component of cell membranes, DNA, RNA, ATP and ADP

• Geology:

- Most phosphorus is within rocks and is released by weathering

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

• Food webs: Plants take up phosphorus when it is dissolved in water

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The phosphorus cycle

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We affect the phosphorus cycle

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

- Wastewater discharge also releases phosphorus

• Runoff containing phosphorus causes eutrophication of aquatic systems

• Household detergents may contain phosphorus

• Potash – i.e. from Saskatchewan – is also useful for plants. The source is buried potassium salts that are mined and used as fertilizers.

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Conclusion

• Thinking in terms of systems is important in understanding Earth’s dynamics

• Earth hosts many interacting systems

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

• Unperturbed ecosystems use renewable solar energy, recycle nutrients, and are stabilized by negative feedback loops

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QUESTION: Review

The term “system” includes all of the following, except:

a) A network of relationships among various components

b) The various components tend to minimize interactions

c) Energy, matter, and information are exchanged between components

d) Energy and matter are valuable inputs to the system

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QUESTION: Review

Which of the following describes a positive feedback loop?

a) It drives a system towards an extremeb) It stabilizes the systemc) It causes the system to move in opposite directions at

the same ratesd) It causes the system to maintain a constant condition

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QUESTION: Review

Which of the following is a correct statement?

a) Energy and matter flow in one direction onlyb) Energy and matter both cycle repeatedlyc) Energy flows in one direction, while matter recyclesd) Matter flows in one direction, while energy recycles

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QUESTION: Review

What is the definition of “net primary production”?

a) Assimilation of energy by heterotrophsb) Elements and compounds that are required for

survivalc) Energy remaining after respiration that is used to

generate biomassd) Assimilation of energy by autotrophs

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QUESTION: Review

Which biogeochemical cycle comprises 78% of our atmosphere, and is contained in proteins, DNA and RNA?

a) Carbonb) Nitrogenc) Waterd) Phosphorus

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QUESTION: Review

Which biogeochemical cycle is being affected by damming rivers, and altering the surface and vegetation?

a) Carbonb) Nitrogenc) Waterd) Phosphorus

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QUESTION: Interpreting Graphs and DataAccording to this graph, which ecosystem has the warmest temperature and most rainfall?

a) Temperate grassland

b) Boreal forest c) Savannahd) Tropical rain forest

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