Agroecosystems

• 1. Ecosystem ~ collective function of organisms and their environment
• 1. What are the five components of an ecosystem?
  2. Food chains ~ flow of energy and nutrients
  3. Diversity ~ natural ecosystems have more biological diversity than agroecosystems 
  4. Competitive exclusion ~ winners and losers of adaptation
  5. Plant succession ~ Natural changes in plant communities over long periods of time
  6. Nutrient cycles ~ natural cycle of nutrients in the system (is balanced in natural ecosystems but must be inputted in agroeconomic systems)
• 1. Agroecosystem ~ ecosystems that have been modified to produce, food, fiber, and/or shelter
• 1. Name 3 important functions that ecosystems provide.
  2. Water regulation
  3. Erosion control
  4. Nutrient cycling
• 1. Compare nutrient cycling in agroecosystems and natural ecosystems.
  2. Natural ~ Nutrient cycles are in balance
  3. Nutrients are not lost unless the cycle is disrupted
  4. Agroecosystems ~ Nutrient cycles are altered
  5. You need to input nutrients in 
• 1. What are the two plant-available forms of nitrogen?
  2. Ammonium (NH4) ~converted from N2 to NH4 by legumes (nitrogen fixing)
  3. Nitrate (NO3) ~ through mineralization, unavailable N converts to NO3
• Natural Ecosystems have what type of diversity (high or low)? High
• Agroecosystems have what type of diversity (high or low)?

  Low (monoculture)
• What level of input comes from humans in a natural ecosystem?

  Low
• What level of input comes from humans in an agroecosystem?

  High
• What level of management do humans have over natural ecosystems?

  Low
• What level of management do humans have over agroecosystems?

  High
• How much breeding is conducted in a natural ecosystem?

  None
• How much breeding is conducted in an agroecosystem?

  High
• How many nutrients are lost in a natural ecosystem?

  None
• How many nutrients are lost in an agroecosystem?

  Some
• 1. What are the TWO risks associated with simplified agroecosystems?
  2. Limited plant diversity ~ not safe (monoculture)
  3. Problems become magnified ~ if there’s a disease on one crop, there diseases in every crop
• 1. Give an example of a simplified agroecosystem from history.
  2. ex) Irish potato famine 
  3. Potato was the primary source of nutrients
  4. Only a few varieties of potatoes grown over large acreage
  5. 1840s - Fungus destroyed potato crop and any stored potatoes
  6. 1 million starved (1/8 of the population)