Sustainability

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Sustainability

• Chapter 12

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Sustainability

• A sustainable activity is one that can be
  continued or repeated for the foreseeable future
• How much human activity is sustainable?

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Sustainability
Can we allow the global human population to
continue to grow?
What resources do we require, and how do we
acquire them? Famine, disease, war
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Sustainability
Peruvian anchoveta fishery
Can we continue to harvest fish faster than they
can replace themselves?
Maximum sustainable yield Fixed quota Fixed
effort
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Sustainability
Can we continue to harvest agricultural crops if
the quality and quantity of soil
deteriorates? New soil - 0.2 t/ha/yr Erosion -
2.0 t/ha/yr
Dust Bowl in central U.S. - 1930s
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Poor Agricultural Practices

• Farming steep slopes

• Removing fence rows

• Moldboard plowing (in fall)

• Overgrazing

• Farming natural waterways

• Compacting soil with large machines

• Lack of crop rotation

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Sustainability
Can we continue to demand and use more water
despite its chronic scarcity and increasing
contamination? Fresh water recycled by water
cycle, but humans now use gt1/2 of accessible
supply
Few water resources remain pristine
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Lowering the Water Table
Original water table
Initial water table
Cone of depression
Lowered water table
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Groundwater Overuse
Groundwater Overdrafts
High
Moderate
Minor or none
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Saltwater Intrusion
Major irrigation well
Well contaminated with saltwater
Water table
Sea Level
Salt water
Fresh groundwater aquifer
Interface
Interface
Saltwater Intrusion
Normal Interface
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Transferring Water from One Place to Another

• Watershed transfer

• California Water Project

• Central Arizona Project

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Saving Water in the Bathroom
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Gray Water Systems
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Sustainability
Can we continue to use the same pesticides if
increasing numbers of pests become resistant to
them? Genetic resistance - accelerated selection
for resistant individuals
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Pesticide Problems

• Persistence

• Bioaccumulation/biomagnification
• - DDT and the bald eagle

• Nonspecificity

Broad spectrum vs. selective pesticides
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Biological Controls Alternatives

• Predators or parasites

• Attractants (pheromones sex hormones)

• Sterilization

• Resistant crops (genetic)