index Expo Renew Nonrenew 2source Slowren Factors Recycle Daypr

Production and Consumption


In any natural ecosystem there is a daily production and consumption of organic matter or oxygen. The proportion of production and consumption is different at night and in the daytime.


  • Photosynthesis and respiration in the forest
  • A self-sufficient economic system with the time sessions or years
  • Diagram


    TN = total available nutrients
    N = storage of nutrients
    J = sunlight
    K, K1, K2, K3 = increasing and decreasing factors
    Q = storage of biomass


    JR = J/(1 + K*N)
    N = TN - K3*Q
    DQ = K1*JR*N - K2*Q


    The graph shows the changes of J (red), Q (blue) and N (green) over a time period of 3 days.
    Source code:

    "What if" Experiments:

  • How would the growth of the forest be different if acid rain reduced the total available nutrients?
  • If this pond was a pond with algae and small fish, what would the changes be if you started with a larger consumer fish?