2. AN ECOSYSTEM IS A COMMUNITY (all organisms) PLUS ABIOTIC FACTORS POPULATIONS AND RESOURCES FLUCTUATE AT A PREDICTABLE RATE OVER TIME

3. POPULATION NUMBERS VARY POPULATIONS- PREDATOR/PREY RELATIONSHIPS ARE LIMITING FACTORS.  MORE PREDATORS =LESS PREY  LESS PREDATORS= MORE PREY  MORE PREY= MORE PREDATORS  LESS PREY= LESS PREDATORS POPULATIONS- PREDATOR/PREY RELATIONSHIPS ARE LIMITING FACTORS.  MORE PREDATORS =LESS PREY  LESS PREDATORS= MORE PREY  MORE PREY= MORE PREDATORS  LESS PREY= LESS PREDATORS

4. PREDATOR - PREY GRAPHS WHEN PREY NUMBER GOES UP, PREDATOR NUMBERS INCREASE. WHEN PREDATOR NUMBER GOES UP, PREY NUMBER GOES DOWN WHEN PREY NUMBER GOES UP, PREDATOR NUMBERS INCREASE. WHEN PREDATOR NUMBER GOES UP, PREY NUMBER GOES DOWN

5. POPULATION NUMBERS (CONTINUED) THESE POPULATION FLUCTUATIONS RESULT IN A STABLE ECOSYSTEM

6. RESOURCES ALSO FLUCTUATE OVER TIME  SOME YEARS RESULT IN A GREAT GROWING SEASON FOR PRODUCERS, THEREFORE INCREASING THE NUMBER OF PRIMARY CONSUMERS.  OTHER YEARS (DROUGHTS) LIMIT PRODUCERS, SO POPULATIONS OF CONSUMERS GO DOWN.  THESE FLUCTUATIONS ARE NATURAL AND INDICATE A STABLE ECOSYSTEM  SOME YEARS RESULT IN A GREAT GROWING SEASON FOR PRODUCERS, THEREFORE INCREASING THE NUMBER OF PRIMARY CONSUMERS.  OTHER YEARS (DROUGHTS) LIMIT PRODUCERS, SO POPULATIONS OF CONSUMERS GO DOWN.  THESE FLUCTUATIONS ARE NATURAL AND INDICATE A STABLE ECOSYSTEM

7. ENERGY FLOW  ENERGY FLOWS THROUGH ECOSYSTEMS AT A FAIRLY CONSTANT RATE  THIS INDICATES A STABLE ECOSYSTEM  ENERGY FLOWS THROUGH ECOSYSTEMS AT A FAIRLY CONSTANT RATE  THIS INDICATES A STABLE ECOSYSTEM