Chapter 4: Biogeochemical Cycles & the Biosphere & the Four Laws of EcologyHolly BarcusMorehead State UniversityAnd Joe NaumannUMSL

Introduction to GeographyPeople, Places, and Environment, 6eCarl DahlmanWilliam H. Renwick

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Biomes

• Global patterns in the biosphere– Associations of plant and animal types

– Similar distributions: highly interconnected• Soil• Vegetation• Climate

– Human impacts• Population growth• Consumption of natural resources

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Recycled & Recycling World

• Studying patterns and relationships, one discovers that the world is one gigantic system composed of intrerconnected and interdependent cycles and sub-systems.

• Everything & everyone is connected!

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Solar Powered World

• Directly or indirectly, all the biochemical systems depend on the energy from the sun.

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Cycles & Balances

• The state of the earth today is the result of past actions, creating a somewhat stable, self-perpetuating ecosystem (at least in human terms). In that system, we can identify cycles (and recycling) and balances that help perpetuate the “climax” condition.

• Human actions can fit in two ways:– Respect cycles & balances and work with them– Upset the cycles & balances to obtain short-term

benefits & then deal with the consequences.

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Systems

• System: any working thing composed of two or more interrelated parts– Closed System: is self-maintaining or perpetuating –

doesn’t need something to start or maintain it. Example: Hydrologic cycle

– Open System: needs something to start or maintain its operation. Example: an automobile

• The entire earth may be seen as a complex, gigantic ecosystem composed of many interconnected subsystems.

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Biogeochemical Cycles

• Recycling processes that supply essential substances to the biosphere– Connect Earth’s subsystems

• Atmosphere, hydrosphere, lithosphere

• Law of conservation of energy and matter– states that energy cannot be created or

destroyed, but can change its form. The total quantity of matter and energy available in the universe is a fixed amount and never any more or less.

• Two important biogeochemical cycles– Hydrologic– Carbon

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Key Cycles

• Rock Cycle (see chapter 3)

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Hydrologic Cycle

• Flows of water among land, sea and air

• 3 states of water– Gas– Solid – Liquid

• All living things are primarily water

The range of earth temperatures allows water to exist in all three states.

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Water: Where is it?

• 96.5% stored in oceans• 2% stored in glacial ice• 0.9% is saline groundwater• 0.8% available as fresh water• 0.014% in rivers and lakes• 0.001% is contained in the atmosphere

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Water Budget

• Accounting of inflows and outflow within a given system

• Evapotranspiration– Sum of evaporation and transpiration– Seasonal variation

• Low in winter• High in summer

• Local water budgets– Compares precipitation and evapotranspiration

Generalized Water Budget:

Water Budget

• Variations reflect the different budgets that exist in different climates in different locations around the world.

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Soil and the Water Budget

• Critical to water budget: soil stores and makes water available to plants.

• Stores water for evapotranspiration (ET)– Soil texture & composition affect how much water soil

can hold• Size of soil particles• Quantity of humus (organic matter)• Degree of compaction

• Infiltration capacity– Good -- – Poor --

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Vegetation and Hydrologic Cycle

• Trees and forests require large amounts of water

• Trees play key role in returning rainwater to the atmosphere – and oxygen– Deforestation affects water balance of regions

• Reduces evapotranspiration• Promotes a less humid climate – climate change

– Ex. Amazon & Congo basins

• Grasses – produce less oxygen than forests– Shallow roots– Variable transpiration rates

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The Carbon Cycle

• Processes that cycle carbon and oxygen between the environment and living things– Photosynthesis

• Determined by climate• Seasonal cycles of solar radiation

– Respiration• Opposite reaction of photosynthesis

– Combustion• Coal, oil, natural gas• Industrial Revolution

• Lithosphere stores carbon

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Nitrogen Cycle

• Nitrogen is essential for plant growth

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Food Chain

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Food Chain Cycle Related to Seasons

• Stage 1

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Aphids Stage 2

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Aphids Stage 3

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Deforestation (particularly tropical rainforests)

• Important influence on biosphere-atmosphere exchanges

• Biomass– Stores carbon & releases oxygen– Forests and trees are key storage sites– Forests filter impurities from the atmosphere– Deforestation through cutting and burning releases

carbon into atmosphere

• Critical regions– Central and South America– West Africa– Southeast Asia

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Soil

• Dynamic, porous layer composed of weathered mineral matter, organic matter (living & dead), water and air. Soil is a “living thing.”

• 5 factors that affect soil properties– Climate– Parent material– Biological activity– Topography– Time

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Soil Formation

• Weathering– Mechanical and chemical

• Water – Volume that passes through rock is important factor– Large volumes of water = lower amounts of soluble

minerals

• Plant and animal activities

• Topography

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Soil Characteristics

• Six principal components of soil– Rocks and rock particles– Humus– Dissolved substances– Organisms– Water from rainfall– Air

• Soil horizons– Layers of substances found in soils– Formed through vertical movement of water, minerals

and organic matter

Topsoil

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Types of Soils

• Soil orders (related to climate & vegetation – a relatively stable symbiosis in nature)– 11 orders

• 47 suborders• 230 great groups• 1,200 subgroups• 6,000 families• Thousands of soil series

• USDA Natural Resource Conservation Service maps

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Climatic Soil Regions

• Humid tropical and subtropical soils– Oxisols and ultisols– Highly weathered & leached - practically no humus

accumulation

• Arid region soils– High in soluble minerals & very little humus

• Midlatitude humid soils– Moderately leached– Moderate amount of humus

• Midlatitude subhumid soils– Fertile – high humus content – “Chernozem”– Associated with grain-producing regions

Soil Regions of the World

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Differing climate & vegetation = different soil types

• How much humus?

• Acid, neutral, or base?

• What texture?

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Soil Problems and Fertility

• Problems– Artificial nutrients not replaced fast enough

• Manure, inorganic fertilizers• High intensity agriculture

– Erosion and desertification – highly related to human use/abuse

• Fertility– Factors = plowing, planting cycles, availability of

nutrients– Restoration of fertility

• Fallow periods• Organic and inorganic fertilizers

• Concern about soil degradation and future food production capacity

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The Four Laws of Ecology

• Human survival may depend on humans understanding and valuing these laws and in considering them whenever decisions affect the environment.

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Four Laws of Ecology: From Barry Commoner’s book The Closing Circle

• Everything is connected– Everything on earth is interconnected much like a

huge spider web

• Everything goes somewhere– Elements of the system may change but don’t cease

to exist

• Nature knows best– What nature creates is biodegradable

• There’s no such thing as a free lunch– There are consequences (costs) for every action

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Everything is Connected

• It may take some time to see some connections.

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Everything Goes Somewhere

• Winter road salt contaminates ground water, eventually causing damage far away.

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Nature Knows Best

• Non-biodegradable chemicals remain in the ecosystem indefinitely, being recycled through the food chain over and over and over.

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There’s no such thing as a free lunch!• Action: clear cutting by lumber companies

Clear Cutting Consequence: mudslide resulting from clear cutting – costs to repair damages

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Seagull Example

1. DDT molecules in the ocean are ingested by plankton, storing DDT

2. Plankton eaten by small fish, storing & concentrating DDT

3. Small fish eaten by larger fish, storing & concentrating DDT

4. Larger fish eaten by seagulls, storing & concentrating DDT

5. Seagulls produce thin-shelled eggs – no chicks hatch

6. Eggs decompose and DDT returns to soil or water to be absorbed at the food chain base and start another cycle

7. Seagull dies returning DDT to soil or water to be absorbed at the food chain base and start another cycle -- #8

DDT is non-Biodegradableand recycles.

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Ecosystem

• Includes all living organisms and the physical area in which they exist

• Fundamental elements– Producers – Consumers – Decomposers– Material/energy needed for production

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Food Chains

• Distribution• Herbivores• Carnivores• Omnivores• Trophic level (Place in the food chain)• Biomagnification

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Biological magnification

• Generally, the higher a species is on the food chain, the greater the magnification of “stored” chemicals.

• Humans are at the top of the food chain

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Why understand the 4 laws?

• Every change in the ecosystem has consequences

• In the past the consequences were relatively small and we could learn from our mistakes

• The technology of today makes it possible for us to make changes with possibly catastrophic consequences

• We must try to ascertain possible consequences before we initiate changes in the ecosystem

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The Reality of the 4 Laws

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Example

• Pollution of the oceans plus the thinning of the ozone layer could be harmful to the phytoplankton (and zooplankton) in the sea– Phytoplankton (microscopic plants) form the basis of

the entire food chain of the ocean– Phytoplankton produce much oxygen (I’ve read

estimates as high as 70% of the oxygen produced come from the phytoplankton)

• Do we really want to risk harming phytoplankton? A mistake can’t be easily undone!

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Four Requirements of Life

All life on earth depends on four requirements:

1.1. SunlightSunlight – the power source or enabler for the life system (climate, plants, animals, etc.)

2. Water

3. Air

4. Soil (land)

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Pyramid of Life

• A change at any level may have serious consequences for everything above it on the pyramid.

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Community Succession

• Sequence• Succession• Climax community

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Biodiversity

• Diversity of species• Stability of community• Biosphere reserves

– UN Biosphere Reserve Program

• Importance of size• Managed landscapes

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Biodiversity is essential

• Do we know the niche of each member of a biotic community?

• Gene pool for future hybrids

• Undiscovered values – don’t throw out baby with the bath

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Biodiversity on a Coral Reef: Click the picture for the video

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Biomes

• Ecosystems grouped by:– Plant types– Animal types

• Named for dominant vegetation/climate

• Typically contain many ecosystems

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Major Biomes

• Forest– Tropical & temperate rainforest– Boreal

• Savannah• Woodland• Scrubland• Grassland• Desert• Tundra

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Tropical Rainforest Biome

• Click the picture to see the video

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Desert Biomes

• Click the picture to see the video

Biomes - Bioregions

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Human and Natural Effects

• Humans influence ecosystems– 37% of land area = cropland or pasture– Desertification

• Local topography and geology– Vegetation and evapotranspiration vary regionally– Wind erosion

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Dangers to Biochemical Systems and Cycles from Human Actions• Desertification

• Deforestation (particularly tropical)

• Loss of biodiversity

• Threats to the base of the food chain– Eutrophication– Pollution– Over fishing

• Soil: erosion & salinization

• Global Warming & ozone depletion

• Water & air pollution

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Changing the “Mix” of a Biome

• Subtraction from a biome– Removing a species

– Removing or altering a natural condition

• Adding to a biome– Introduction of exotic plants

– Introduction of exotic animals

– Introduction of exotic diseases

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Removing species

• Predators in North County & most of MO– Deer– Rabbits & squirrels

• Removing forest fires?????????– Jack pine

• Crocodiles in African rivers

• Removing a vital link in the biome may remove all that was dependent on it.

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Introducing Exotics

• Rabbits in Australia• Kudzu in USA• Fungus carrying moth in USA• Smallpox, diphtheria, whopping cough,

syphilis, “childhood diseases” etc., to the Americas– Danger today of terrorists using exotic

microbial agents as weapons

• Historians call this the Columbian Exchange!

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Saltcedar: shrub native to Eurasia & Africa

• 12 varieties in USA – natural, vigorous hybrid

• Long taproot depletes springs in US West

• Salt accumulates on leaves – when leaves fall, soil becomes to salty for native plants

• Vigorous grower – crowds out native plants

• Threatens habitat of 31 endangered species

• Spreading to 40,000 acres per year

• Resists fire & chemical sprays - insects (hybrid)

• Clogged California rivers

• Displaced shorebirds in Kansas

Land Use in the USA

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Human Interaction with Water Upsets Many Cycles

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Water & Water Quality

• Availability of Water• Modification of Streams• Water Quality• Agricultural Sources of Water Pollution

– Fertilizers, Biocides, Animal Wastes

• Other Sources of Water Pollution– Mining & Industry

– Municipalities and Residences

• Controlling Water Pollution

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Modification of Streams

• Levees increase flooding downstream and across the river.

• “straightening” streams increases the volume of water downstream

• Dams may impede the movement of fish – fish ladders needed for salmon in northwest

• Canals connecting streams may allow the spread of undesirable species – zebra mussel and sea lamprey

• Destruction of wetland habitats

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Levee – modifications of streams

• The floodplain (basin) is nature’s release valve for floods and provides a wetland habitat for many species of plants and animals. A levee reduces its ability to moderate flooding and sustain a wide variety of plants and animals

More flooding

Levee

Man-made levees are

higher than natural ones.

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Water Quality

• Nature pollutes water at a rate which nature can process in a reasonable time and/or distance from the contamination.– Animal feces– Decaying plant and animal material

• Humans have overloaded the natural system and that is what we call “pollution.”– More than nature can process in a reasonable

time and/or distance– Non-biodegradable chemical compounds

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Sources of Water Contamination

• Microbiological contamination – septic tanks & sewage discharges– sanitary landfill sites – farms (liquid manure storage, animal production)

• Chemical contamination – septic tanks (organic contaminants, disinfectants,

etc.) & sewage discharges – sanitary landfill sites – farms (fertilizers, pesticides, herbicides) – leakage from oil tanks or chemical spills – highways (de-icing salt)

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Water Quality continued. . .

• Agricultural run-off creates problems– Causes excessive growth of algae and other plants, leading to

eutrophication – Nitrate build-up in reservoirs threatening the life of infants and very

ill persons – nitrates to nitrites.

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Urban Run-off Contributes More to Flooding

• Farmland and natural land retains water longer, releasing it more slowly to the streams

• Urban surfaces are non-absorbent of water and produce greater volumes of run-off more rapidly

Natural surface Urban surface

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Urban -- Rural

• Consider this: In most urban areas, the finest, level farmland is used to build subdivisions, shopping malls, etc. – retiring the best farmland and increasing runoff/flooding.

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Damage to the seas and delicate biomes like the tundra

85Accidental oil spills can harm the sea biome and nearby coastal biomes.

Danger at sea

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Each Citizen Has a Role to Play

• Different world views cause cultures to respond to nature, the physical world, in different ways – some life-affirming and others life-negating.

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Many problems don’t start within or stop at our borders!

End of Chapter 4