Numerical analysis on the dynamics of communities for sessile colonial animals

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I estimated quantitatively space competition of which model was constructed by simulating the ecology of encrusting colonial bryozoans. At first, there is no bryozoa on the hard bottom. Larva of bryozoans settle randomly by the same number on the bottom every day. The larva grow to zooids soon. Zooids increase in their numbers with time according to the species and the size. The clump of zooid is called as the colony. When zooids contact each other, the space competition occurs. The competition expressed as over-growth of one zooid over the other zooid. In this case, I postulate the limiting value of over-growth which is expressed by the species pair and the size ratio of two species. When the size ratio becomes larger than the limiting value, the one species grows over the other species. Over-grown zooids are killed and the one species occupy thus over-grown area. The space continues to fill with time and reached to completely covered area. The simulation finishes in this state. The results were as follows :There is fairly large variation between simulation experiments owing to random settling of larva to bottom, even though population parameters and competition parameters are the same pattern. This means that if the number of repeats is small, the contrary result to true one is possible.The covers of two species in stand-off system are equal in average, and the same is true in even win-loss system.However, the variation of covers is smaller in the stand-off system than in even win-loss system.The coverage of competing species change catastrophically on 1 of the limiting value.Even weak species occupy fairly large space, if there is strong species which suppress the competing species with weak one, as described as the indirect effect.Increasing in species number from 3 to 10, there is a trend that the relative difference in covers of species decreases.