Environmental Science The Course

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Environmental Science The Course!

• Part 1. Interrelationships
• Part 2. Ecological Principles
• Part 3. Energy
• Part 4. Human Influences
• Part 5. Pollution and Policy

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Part FourHuman Influence on Ecosystems

• Chapter 12 Human impacts on resources and
  ecosystems.
• Chapter 13 Land-use planning.
• Chapter 14 Soil and its uses.
• Chapter 15 Agricultural methods and pest
  management.
• Chapter 16 Water management

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Chapter 12

• Human Impacts on Resources and Ecosystems

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Human Impacts upon Earth

• Historical basis of pollution
• Pollution is any product released in the amounts
  and duration that cause harmful effects.
• Pollution is affected by two primary factors -
  technological status and population size.
• Bio-degradable vs. non-biodegradable

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Population Size

• waste produced faster than ecosystem could
  process
• Urban centers enhanced this problem
• Eliminating misery and disease often caused
  other problems - Pesticides
• Often, pollution is in the eye of the beholder

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Renewable and Non-renewable Resources

• Resources - things usable by humans but cannot be
  created by humans
• concept of limited and non-limited
• Intensive exploitation moves unlimited to limited
  resources
• Renewable vs. non-renewable renewable does not
  mean inexhaustible!
• Natural processes soil / water

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Mineral Resources

• Locations of mineral resources is not based on
  political boundaries - international trade
• U.S. and Canada have about 6.0 of the worlds
  population and consume about 30 percent of the
  worlds resources
• Costs - Economic, Energy, Environmental Costs -
  Externalities

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Steps in Mineral Resource Uses

• Exploration
• time and technology
• Some energy
• Some environmental - becomes more intense as
  easy resources are consumed
• Mining
• labor
• equipment and energy
• Environmental - mine tailings, water pollution
  and erosion, land disturbance

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Refining

• labor
• equipment
• energy
• environment - air pollution and water pollution

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Transportation

• Energy
• Some environmental - exhaust, construction of
  transportation routes, scenic issues, habitat
  fragmentation

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Manufacturing

• labor
• equipment
• energy (large amounts)
• environmental - air pollution, water pollution

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Recycling

• Can save significant cost by using materials
  which do not require all of the above steps
• As energy costs go up, recycling will become more
  common
• Currently, many pay the environmental cost,
  rather than the few who reuse the product

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Pristine Areas

• Remote areas with harsh conditions are typically
  pristine (arctic poles, mountain tops, open
  ocean)
• Areas that wont support agriculture
• Other areas which until recently have been
  unaffected are being impacted

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Pristine Areas

• Typically if an area will support agriculture or
  other human uses, it is the first to go.
• Many parks and protected areas have been
  designated as pristine but this is becoming
  more rare
• Wilderness Areas Where humans are visitors and
  do not remain
• (U.S. definition, Wilderness Act 1964)

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Modifications by Humans

• Forests - originally 1/2 of the U.S., 3/4 of
  Canada, 9/10 of Europe, and much of the rest of
  the world
• Very large demand for wood
• Sustained yield harvest rate equals rate of
  re-growth
• Tropical forests are currently being treated as
  nonrenewable resources, with extremely fast
  depletion (4 1981 to 1990 globally)

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Forests

• Reduce energy in rainfall and practically stop
  erosion by slowing runoff
• Water is evapotranspired in large volumes
• Shade and humidity moderate temperature extremes

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Forests

• Tropical rain forests trap much CO2, but are in
  areas of highest population growth
• Management of forests require a compromise
  between economic forces and environmental
  viewpoints

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Harvest Considerations

• Clear-cutting
• Patchwork clear-cutting (strip)
• Selective harvesting
• Reforestation
• Different species need different things in a
  forest (e.g. Red Cockaded Woodpecker)

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Forests

• Deciding what to do requires a conscious decision
• Can assign a value to the world forests
• Can assign value to wildlife and water within a
  forest
• Wilderness value, however, is very difficult to
  determine forest cannot be both an economic
  resource and a wilderness area

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Rangelands

• Arid and semi-arid lands that cannot support
  typical agriculture, but can support some grazing
  animals
• Grazing animals selectively reduce some plant
  species (and encourage others). Managers do the
  same.
• Most grazing animals which are herded are exotic
  species and reduce native species

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Rangelands (continued)

• Population pressures force people to graze too
  many animals (Tragedy of the Commons)
• Remove trees for wood (nutrient e.g., legumes,
  removal)
• Land may be pushed towards desertification

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Aquatic Systems

• Large areas of the ocean are still considered
  pristine
• Most productive areas in the ocean are close to
  the shore nutrients / sunlight/ offshore
  currents bring nutrients up from the bottom
• Fishing selectively removes some species
  (lobster, shrimp, swordfish)

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Aquatic Systems

• Harvesting should occur during the exponential
  growth phase
• most freshwater systems have been altered by
  humans
• water quality changes
• exotic species
• thermal pollution

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Aquatic systems

• Many systems are manipulated to enhance some
  desirable species for food or sport.
• Difficult to predict all the consequences of
  managing large natural systems.

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Wildlife Management

• Improving conditions for species desirable to
  humans. Manipulate one or more of the following
• Food and water
• Cover (shelter)
• Escape from predators
• protection from weather
• resting and sleeping
• mating and raising young

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Wildlife Management

• Must understand the niche very well before
  attempting to improve its habitat (i.e., manage
  it)
• Trying to improve the habitat of one species
  often harms the habitat of another (introduced
  vs. native)
• Migrating species require special considerations

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Natural Selection and Evolution

• Extinction - elimination of all individuals of a
  particular species (local and global)
• Natural phenomenon - estimated that only about
  1-2 of all species that have existed are still
  around today.
• Speciation - appearance of a new species

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Extinction

• Since things change, a species must adapt or
  become extinct
• Extinction happens more often when
• Species has a small population
• Dispersed individuals
• Occur in small, restricted areas
• Species is very specialized

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Accelerated Extinction

• Humans are among the most successful species
  currently on earth
• Adaptable
• intelligent
• high reproductive activity
• few enemies

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As Human Population Grows

• other species displaced (habitat alteration)
• Species utilized as food
• Used as ornaments
• Used for medicine
• Eliminated as pests
• All accelerate extinction

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Why Worry About Extinction??

• Many species may be useful to us (food and
  medicine).
• Certain species play key roles in the ecosystem
  that we utilize
• Most people find nature beautiful, monocultures
  are disturbingly sterile
• Do all species have a fundamental right to
  exist????

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Actions

• Protection of threatened and endangered species
• Currently, more action in developed nations than
  in less developed nations
• Bias in protecting certain species
• birds
• mammals
• butterflies
• a few mollusks, fish, and plants

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Actions

• International Union for the Conservation of
  Nature and Natural Resources
• Work without much power but much prestige around
  the world, particularly in less developed nations

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Actions

• US Endangered Species Act (1973)
• Attempts to protect threatened and endangered
  species from governmental actions (via
  jurisdiction)
• Endangered Species Review Committee
• 7 member committee
• Can grant exceptions to the Endangered Species
  Act (God Squad)
• Does economics outweigh ecological effects? (case
  of the snail darter, 1978)