Computer simulation of world systems: biogeochemical cycles

Through the use of computer simulation of three biogeochemical cycles—carbon, nitrogen, and phosphorus—we have shown that DDT poisoning of ocean producers (plants) can cause their growth to be limited by nitrogen, whereas ordinarily it is limited by phosphorus. We must qualify what we have shown because we restricted the simulation by representing only two ecosystems (ocean and land), by using simplified equations for some flow rates, and finally by estimating data for some biomass values and for some flow rates. In order to remove some of the restrictions on the simulation, we are extending it so that we may include in it knowledge of our own, of ecologists, and of systems analysts. By extending it, we are increasing our ability for using it to understand, and consequently to predict and control, the behavior of the interacting biogeochemical cycles of the world.