8 Anthropogenic Impact and Sustainable Natural Resources

Question 1

• Driven by human
  consumption of organic
  resources, especially related
  to tropical forest destruction
• Many natural landscapes
  have been broken up,
  fragmenting habitat into
  small patches

Answer 1

Habitat Destruction

Question 2

• Chemical cycling in an ecosystem depends on
  – The web of feeding
  – Relationships between plants, animals, and detritivores
  – Geologic processes
• Altering an environment can cause severe losses in chemical cycling
  – Erosion
  – Acid rain

Answer 2

Ecosystem alteration can upset chemical cycling

Question 3

• Major changes in terrestrial ecosystems disrupt chemical cycling
• These changes can increase nutrients in aquatic ecosystems
  – Algal and cyanobacteria blooms
  – Eutrophication

Answer 3

Effects of nutrients on freshwater ecosystems

Question 4

• Process where toxins are concentrated at each successive trophic level in the
  food chain
• Exemplified by DDT (dichlorodiphenyltrichloroethane), known nerve
  poison agent against insect pests
• Makes egg shells of birds very weak and brittle
• Affects the nervous system in humans
• E.g. California Condor

Answer 4

Biological magnification

Question 5

• Carbon dioxide emissions have
  caused atmospheric CO2
  concentrations to increase 14%
  since 1958
• Increase is due to combustion of
  fossil fuels and burning of wood
  removed by deforestation

Answer 5

Greenhouse effect

Question 6

• OZONE LAYER - protective layer made up
  of O3 in the stratosphere that absorbs ultraviolet
  radiation
• O3 is reduced to atmospheric O2 by CFCs
  (chlorofluorocarbons)

Answer 6

Ozone layer depletion

Question 7

• When exotic species are introduced to ecosystems and establish selfsustaining populations, the endemic species in that ecosystem that have
  not evolved to cope with the exotic
  species may not survive.

Answer 7

Introduction of exotic species.

Question 8

• Human harvesting of wild plants or
  animals at rates exceeding the
  ability of populations of those
  species to rebound.
• Commercial fishing has greatly
  reduced the global population of
  bluefin tuna

Answer 8

Overexploitation

Question 9

• Extermination of keystone species can
  drastically change a community structure

Answer 9

Disruption of interaction networks

Question 10

– A species whose impact on
its community is larger than its
biomass or abundance indicates
– Occupies a niche that holds
the rest of its community in
place

Answer 10

Keystone species - have a
disproportionate impact on diversity

Question 11

• refers to an organism that
  plays a critical role in its
  environment, one that
  may become apparent
  only once it is removed
  from its ecosystem
• species that, despite low biomass, exert strong effects on the structure of the communities they inhabit

Answer 11

Keystone species

Question 12

Ten Environmental Principles

Answer 12

1. Finiteness of Resources
   – Ours is a finite earth.
2. Population Growth and Carrying Capacity
   – An ecosystem can only support a certain number of individuals at any given time.
3. Materials Cycle/Pollution
   – Everything must go somewhere.
4. Balance of Nature
   – Nature knows best.
5. Diversity and Stability
   – All forms of life are important.
6. Interdependence
   – Everything is connected to everything else.
7. Change
   – Everything is always changing.
8. Stewardship
   – Nature is beautiful and we are all stewards of nature.
9. Cooperation
   – Improvement and management of the environment at all levels involve the concerted
   effort of many people.
10. Sustainable development
    – Economic activities may be pursued without jeopardizing the survival of future
    generations and not at the expense of a degraded environment.