Exploitation of Food Resources

1
Exploitation of Food Resources

• Of 250,000 species of plants described only 100
  are used to feed the world
• 15 plants and 8 animal species supply 90 of our
  food
• Primary food crops
• Wheat - staple food of over 1/3 of global pop.
• Rice - large yield, grows continuously, tropics
• Corn / Maize - staple in S. America Africa, fed
  to cattle in US
• Potato - in developed countries

2
Other foods consumed

• Fish, meat and animal products (milk, eggs,
  cheese) - EXPENSIVE!
• 80 of meat and milk produced is consumed by only
  20 of global population
• Meat consumption per capita per year
• US 110 kg
• UK 75 kg
• China 21 kg
• India 1.1 kg

3
Inefficiencies in terrestrial systems

• More than one third of grain harvest (37) is
  used for animal feed - not human consumption
• This is very inefficient as the energy of
  assimilation is only about 10 (Fig. 3)
• One calorie of grain-fed steak requires at least
  10 calories for production
• One calorie of chicken requires 12 calories
• Meat production is very inefficient!

4
Terrestrial versus aquatic systems

• Most food from terrestrial systems is harvested
  from lower trophic levels - producers and
  herbivores
• Food from aquatic systems is harvested from
  higher trophic levels
• Efficiency of fixation of solar energy is lower
  in aquatic systems because of absorption and
  reflection by water

5
Improving use of food resources

• Maximize yield
• Improve storage
• Improve distribution methods
• Change eating habits (i.e. eat less meat)
• Population control