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Salt Marsh

Description:

A simple model of salt marsh in a temperate latitude is simulated under rhythmic influences of sun, river inflow and seasonal changes in the magnitude of tidal flushing. Nutrients and organic matter are received from the river inflow and flushed out by tidal exchange. Organic production of the marsh plants is a function of the nutrient levels and the sun; nutrients are recycled from plants and consumers.

Examples:

  • all systems with rhythmic inputs such as those from sun, climate and tide
  • "filter"
    		•  Diagram

    Variables:

    Q1 = Nutrients
    Q2 = Plants
    Q3 = Dead organic matter
    D1, D2, D3 = increasing of Q1, Q2, Q3
    K... = interaction coefficients

    Equations:

    R = I/(1 + K0*Q1)
    D1 = J - K5*R*Q1 + K3*Q2 + K9*Q3 - K4*Q1*E
    D2 = K1*R*Q1 - K7*Q2 - K2*Q2
    D3 = K7*Q2 - K8*Q3 - K6*Q3*E

    Simulation:

    The graph shows the changes of I(sun), E(tide), J(river), Q1(nutrients), Q2(grass), Q3(peat) over a time period of 5 years.
    Source code: Saltmrsh.java

    "What if" Experiments:

  • What is the effect of a small initial storage of organic matter on the oscillations in the system due to the external input oscillations?
  • What is the effect of increasing the tidal range, inflow of sunlight, inflow of nutrients?
    		•