Community Ecologyand Ecosystems

Chapter 53

Ecological communities are composed of all species populations that cohabit an area

An ecosystem is an ecological communityand its abiotic environment

Community EcologyCommunities are composed of all of the species that cohabit an area.

Are species distributed individualistically? Or are communities composed of coevolved, interactive

assemblages?

Succession

Competitive ExclusionNo two species can occupy the same niche at the same site

Galapagos Finches

CharacterDisplacement

Ecosystems

Food Chains

Food Webs

Primary Productivity

Energy Flow and Energy Pyramids

Energy FlowNumbers of Individuals per Trophic Level

Human Effects on the Environment

Ecological Magnification

Forests rely on their nutrient pools,which can be leached away after deforestation.

Acid Deposition

Greenhouse Effect

Global Warming Global Warming

Our fragile atmosphere

atmosphere

Is Global Warming Happening?Is Global Warming Happening?

Is Global Warming Happening?Is Global Warming Happening?

A Very Controversial TopicA Very Controversial Topic

Must know the agenda of Must know the agenda of

“authorities”“authorities”

Must know the Must know the agenda of “authorities”...agenda of “authorities”...

There areThere are 3 schools of thought:3 schools of thought:

1. This is an environmental emergency requiring immediate action1. This is an environmental emergency requiring immediate action

2. The reality of global warming, or at least the human influence 2. The reality of global warming, or at least the human influence requires better research before initiating expensive interventionsrequires better research before initiating expensive interventions

3. Economic factors require the highest priority,3. Economic factors require the highest priority,subordinating environmental considerations subordinating environmental considerations

Is Global Warming Happening?Is Global Warming Happening?• The three warmest years on record are 1998, 1997, 1995• The three warmest years on record are 1998, 1997, 1995

• 1998 may have been the warmest year in 1200 years• 1998 may have been the warmest year in 1200 years

• The last two decades have been the warmest in 1200 years• The last two decades have been the warmest in 1200 years

• The spring green wave occurs about 6 days earlier than 1959• The spring green wave occurs about 6 days earlier than 1959

• Autumn brown wave are delayed by about 5 days compared to 1959• Autumn brown wave are delayed by about 5 days compared to 1959

• The frequency of extreme weather is increasing in some places• The frequency of extreme weather is increasing in some places

• Ice caps and glaciers are retreating, permafrost is melting• Ice caps and glaciers are retreating, permafrost is melting

• Temperate species ranges are moving to higher latitudes• Temperate species ranges are moving to higher latitudes

• Oceans levels are rising …with alarming implications• Oceans levels are rising …with alarming implications

Over the last 1000 years, temperatures have been decreasing somewhat, until about the advent of the industrial revolution. Since then

temperature has increased.

Melting of the permafrost in AlaskaMelting of the permafrost in Alaska

Global Climate Change

Range Alterations

Global Climate Change Models

Global Climate Change Models - Critical Need: Data

Effects on agriculture

• Agricultural productivity has increased 8% more than population growth since WW II

• U.S. agricultural production has played a major role

• Factors:a) Plant breedingb) Energy subsidiesc) Great climate and great soils geographically superimposed

The American Breadbasketgood soils and good climate

The American Breadbasketunder global warming

good climate moves to the SW over poor soils

Ice melting - Ocean level rises

• Several Pacific islands already submerged

• Maldives, Bangladesh threatened

• US low-lying areas threatened

• Worst scenario ...increase of 4° C would melt ice caps and raise oceans 200-400 feet, placing all agricultural regions and all big cities except Mexico City under water …as destructive as nuclear war

US Flooding with 1 meter rise in water level

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

QuickTime™ and aCinepak decompressor

are needed to see this picture.

IPCCU.N Intergovernmental Panel on Climate Change

• IPCC was formed in response to growing scientific consensus that global climate changes might be occurring

• 1995 IPCCa) The most definitive scientific statement about global warmingb) Confirmed that global warming is happeningc) Concluded that human influence is implicated

• Uncertainty factors:a) Relative impact of natural and human causesb) How rapidly warming will occurc) How severe the warming will bed) Where it will be most pronounced

How Is Global Warming How Is Global Warming

Happening?Happening?

How Is Global Warming How Is Global Warming Happening?Happening?

Greenhouse effects resulting from Greenhouse effects resulting from

human increases in greenhouse gasses human increases in greenhouse gasses

Greenhouse EffectGreenhouse Effect

Radiation is always converted to a longer

wave length when moving through a denser medium

Lightshort-wave radiation Heat

long-wave radiation

Principle Greenhouse Gasses

• Carbon Dioxide (CO2 ), from combustion & deforestation

• Methane (CH4 ), from natural and man-made causes

• Nitrous oxide (N2O ), from pollution

• Chlorofluorocarbons (CFCs), from air conditioners * refrigerators

• Ozone (O3 ), from pollution and natural causes

CO2 levels have been increasing for at least 50 years

CO2 concentration over the past half century in

Hawaii

CO2 and temperature changes over the last 50 years are correlated - suggesting but not proving possible causation

Over an even longer time period, 400,000 years, CO2 levels have oscillated on a grand scale, but the recent increase in CO2 levels seems

unique over this time period.

IPCC Conclusions:

Global warming is happening

Human influence is implicated

Some pollutants cool the atmosphere by blocking light from entering

• Aerosols of some pollutants can do this(e.g., sulfur emissions from industry and volcanic activity)

• Effects short-term(particles suspended for days or weeks, versus GH gasses lasting hundreds of years)

• Only works during day time(versus GH gasses that re-radiate heat day and night)

• Cooling effect of aerosols < Heating effect of GH gasses

Eruption of Mount Pinatubo

massive sulfur aerosolemissions in 1991

global cooling in 1992-3

Stratospheric Ozone Layer

The ozone hole 10 September 2000The first major city is exposed in southern Chile

What are the effects of increased UV radiation?

An increased incidence of skin cancers? Other?

International Congresses• Kyoto …western nations, especially US avoided

real sacrifice

• Hague, fall 2000 US influence emphasizes economy

• reforestation efforts to counteract CO2 without reducing CO2 emissions

• Buying credits from other countries CO2 emission controls without reducing US emissions

• US not taxing energy, encouraging energy use and production

8 major US environmental groups may boycot meetings in protest of US policies

Is Global Warming Happening?Is Global Warming Happening?• The three warmest years on record are 1998, 1997, 1995• The three warmest years on record are 1998, 1997, 1995

• 1998 may have been the warmest year in 1200 years• 1998 may have been the warmest year in 1200 years

• The last two decades have been the warmest in 1200 years• The last two decades have been the warmest in 1200 years

• The spring green wave occurs about 6 days earlier than 1959• The spring green wave occurs about 6 days earlier than 1959

• Autumn brown wave are delayed by about 5 days compared to 1959• Autumn brown wave are delayed by about 5 days compared to 1959

• The frequency of extreme weather is increasing in some places• The frequency of extreme weather is increasing in some places

• Ice caps and glaciers are retreating, permafrost is melting• Ice caps and glaciers are retreating, permafrost is melting

• Temperate species ranges are moving to higher latitudes• Temperate species ranges are moving to higher latitudes

• Oceans levels are rising …with alarming implications• Oceans levels are rising …with alarming implications

Must know the Must know the agenda of “authorities”...agenda of “authorities”...

There areThere are 3 schools of thought:3 schools of thought:

1. This is an environmental emergency requiring immediate action1. This is an environmental emergency requiring immediate action

2. The reality of global warming, or at least the human influence 2. The reality of global warming, or at least the human influence requires better research before initiating expensive interventionsrequires better research before initiating expensive interventions

3. Economic factors require the highest priority,3. Economic factors require the highest priority,subordinating environmental considerations subordinating environmental considerations

Our fragile atmosphere

atmosphere