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Resources
What are Resources?
• Resource- An available supply that can be
drawn on when needed
• Humans are most consistently impacting their
environment through their quest for
resources.
– The types of resources are limitless, but can
basically be defined as an environmental factor
that is desirable to somebody.
– Basically if there is somebody who wants
something, we can consider it a resource
When resources are freely available
The Tragedy of the Commons- Garrett Hardin (1968)
1. “commons” – any freely available resource shared by a
group of people
–
2.
Hardin believed that people are greedy and will act in their
own short-sighted self-interest, depleting resources until
the “commons” collapses
–
3.
4.
Ex. Fish, forests, clean air, water, pasture land, etc.
Each person attempts to maximize their portion of the resource
at the expense of others
As populations density increases, “commons tragedies”
increase.
Take home message: Any resource openly shared will
eventually be destroyed because everyone will use it and
no one will be responsible for preserving it
Human Activities- Tragedy of the Commons
Overexploitation of cod fishery- grand banks. Fishery
was found in international waters, so boats from many
different countries were harvesting fish. Each group was
racing to catch the fish before another ship. No one was
concerned about the stability of the fish population,
only their own profits.
Quick Activity
• Classify the following resources as renewable or
nonrenewable:
–
–
–
–
–
–
–
–
Solar energy
Wind/air
Water
Fossil fuels
Metals
Soil
Plants
Animals
Types of Resources
• Environmental resources can be classified into two categories:
– Renewable =can regenerate and are replaceable (trees,
water), but not necessarily unlimited
• The classification “renewable” depends upon the context in which you
use it. (For example, a forest is not renewable, because the climate would
change if all trees were cut down, but individual trees are renewable)
• Think replenished in the short term 1-10 years…
– Nonrenewable = cannot be replenished by natural
processes (fossil fuels, coal, oil, natural gas)
• Sustainable use = way of using natural resources at a rate that
doesn’t deplete them to make sure renewable resources are
available for future generations
Renewable resources
• Human activities affect the supply and the quality of
renewable resources including:
– Land resources
– Forest resources
– Ocean resources
– Air resources
– Water resources
Changing landscape
• Past and present humans have had a powerful influence on
the physical and living world by modifying their environment.
• Our practices are changing the environment!
– From deforestation to fishing
• We used the environment for food, medicine, wood, and fiber
• We introduced new species, predators, agriculture, industry,
and disease
• The world is very different from what it was long ago.
• Think of Earth as an island – all of the organisms that live on
Earth share limited resources and increasing population sizes
place greater demands on the biosphere
Land resources
• Provide space for cities and suburbs, raw materials for
industry, and fertile soil with nutrients and moisture to
grow plants with roots to hold soil against rain and wind
– Negative activities:
• Soil erosion = wearing away of surface soil by water and
wind (usually results from removing roots that hold soil
through plowing, mowing, road building, etc.)
– Typical midwest high plains field loses 47 tons of soil/year
– Soil is the top pollutants in most aquatic systems
• Desertification = turning once productive areas into
deserts (usually results from farming, overgrazing, and
drought)
– Positive activities:
• Sustainable agriculture = practices that reduce soil
erosion by conserving soil’s properties
Sustainable Agriculture
Section 6-4
Cover Crops
Legumes, grasses, and other
cover crops recycle soil nutrients,
reduce fertilizer need, and
prevent weed growth.
Controlled Grazing
By managing graze periods and herd
densities, farmers can improve nutrient
cycling, increase the effectiveness of
precipitation, and increase the carrying
capacity of pastures.
A
Contour Plowing
Contour plowing reduces
soil erosion from land runoff.
On hilly areas, plowing is done
across the hill rather than
straight up and down.
Biological Pest Control
The use of predators and parasites
to control destructive insects
minimizes pesticide use as well as
crop damage
B
C
Yr. 1
corn
oats
Yr. 2
corn
alfalfa
oats
alfalfa
Crop Rotation
Different crops use and
replenish different nutrient
By rotating crops, the loss
alfalfa
(plowed in) of important plant nutrients
is decreased.
alfalfa
Yr. 3
Go to
corn
Good
Bad
Forest resources
• Provide wood for homes, paper, fuel and “lungs of the
Earth” because they remove carbon dioxide and
produce oxygen, store nutrients, provide habitats and
food, moderate climates, limit soil erosion, and protect
fresh water supplies
• Negative activities:
• Deforestation = loss of forests leading to:
– soil erosion, loss of biodiversity, ecosystem services
– Increase in likelihood of global climate change
Clear Cutting
Forest Resources
• Positive activities:
– Forest Management= actively monitoring
and influencing the forest to improve
quality and production of timber
– Sustainable forestry= plant, promote
growth, manage, harvest and replant trees
to preserve the ecosystem
• Harvest trees at low levels, replanting seedlings to
replace harvested trees.
• Selective Cutting- remove only mature, high value
trees, leave forest intact
Sustainable
Practices
Ocean resources
• Provides protein-rich food (cod and shrimp), plankton
produces oxygen and fixes CO2, Controls climate of
planet
– Negative activities:
• Overfishing = fish are being harvested faster than
they can reproduce
• Bycatch= organisms (invertebrates, dolphins,
sharks, turtles, etc.) caught unintentionally while a
fishery targets other species
– May be sold
– May be disposed of
• World wide, only
10 percent of
original predatory
fish populations
remain in the
worlds oceans
• Industrial fisheries
reduce biomass by
an average 80
percent in 10-15
years
Fishing Down Food Webs
Practice in which fisheries simply concentrate
on smaller species, once the larger ones have
been overexploited
Now a common practice
Since 1950- mean trophic level of landings
world wide has fallen
Down the web…
• Past 45 years:
– Shift from large piscivorous fish, to small
invertebrates and planktivorous fishes, especially
in the northern oceans.
• These shifts tend to interrupt entire food
chain, and can result in abundance of
unusable species
– Norway Pout  Krill  copepods
–  More valuable commercial species
Consequences of Fishing Down
consist of:
 a gradual loss of large organisms
 loss of species diversity
 loss of structural diversity
 gradual replacement of recently evolved,
derived groups (marine mammals, bony
fishes) by more primitive groups
(invertebrates, notably jellyfishes, and
bacteria)
Japanese Long Lining
Data from Japanese long line fisheries
illustrates the decline of top trophic level fish
around the world.
Japanese long line fleet is the most extensive
in the entire world, covering all oceans except
the circumpolar seas
Long lines used to catch 10 fish per 100 hooks,
now lucky to catch 1
Three Habitat Types
• Pristine
– Top predators present with large biomass
– Benthic fauna- abundant structure forming and sessile
organisms
• Exploited
– Declines (size of catch, number of individuals, trophic level
of catch ; also decline in benthos)
• Fully degraded
– Most species absent, including key-stone species
– Combined with pollution may result in a “dead zone”
Conclusions (same as always)
 Protected (no fishing) areas need to be created
 In the next decades, fisheries need to concentrate on
rebuilding stocks, with respect to the food webs that
used to exist.
 Difficult in the beginning, but benefits in the long term: if
stocks increase only 1/3 to 1/10 of the effort may be
required to reach current catch levels
 One way to accomplish this is to reduce by catch by a
large amount (suggested that up to 50% of fishing
mortality needs to be avoided for stocks to recover)
Section 6-2
Growth of Fish Catch
Larger fishing boats with better technology for
locating and catching fish
World Fish Catch
Amount of Fish per Person
(kilograms)
Total Catch
(million tons)
Year
Go to
Section:
World Fish Catch per Person
Year
Ocean- Positives
• Positive activities:
– Limit the catch of fish populations
– Aquaculture = farming of aquatic organisms
– Reducing bycatch- improved methods and
technologies
– Creation of marine preserves
Air resources
• Used to breathe
– Negative activities:
• Pollutant = harmful material that can enter the biosphere
through the land/air/water
– Smog = mixture of chemicals that results in a gray-brown haze in the
atmosphere mostly due to car exhausts and industrial emissions
causing respiratory conditions
– Acid rain = mixture of acidic gases (nitrates and sulfates) from
combustion with water vapor- damaging plants, soil and water
– Positive activities:
• Clean-air regulations and controlling emissions has
improved air quality
Section 6-2
The Formation of Acid Rain
Emissions to Atmosphere
Nitrogen oxides
Sulfur dioxide
Chemical Transformation
Nitric acid
Sulfuric acid
Condensation
Dry Fallout
particulates, gases
Industry
Go to
Section:
Transportation
Ore smelting
Power generation
Precipitation
Acid rain, fog,
snow, and mist
Water resources
• Billions of gallons of water are used daily by Americans for
drinking, washing, watering crops and making steel
(“everyday use”)
– Negative activities:
• Our renewable water supply can be limited by drought, overuse, oil
spills, improperly discarded chemicals and waste (sewage)
• High levels of nitrogen and phosphorous due to excess fertilizer
runoff- causes:
• Eutrophication- excess algae growth and oxygen depletion
– Positive activities:
• Protect natural cycles because plants naturally filter and purify water
= Fresh Water Wetlands Act
• Water conservation
• Clean Water Act
• Low flow fixtures are limiting waste water
Excess Phosphorus and Nitrogen