Numerical analysis on the dynamics of communities for sessile colonial animals

通过模拟结壳苔藓虫群落的生态，定量估算了该模型的空间竞争。起初，在坚硬的底部没有苔藓虫。苔藓虫幼虫每天以相同数量随机落在底部。幼虫很快就会长成动物。根据动物的种类和大小，它们的数量会随着时间的推移而增加。这一群动物被称为群落。当动物相互接触时，就会发生空间竞争。竞争表现为一种动物对另一种动物的过度生长。在这种情况下，我假设了过度生长的极限值，该极限值由种对和两种的大小比表示。当大小比大于限制值时，一个物种比另一个物种生长。过度生长的动物被杀死，一个物种占据了过度生长的区域。空间不断被时间填满，直至完全被覆盖。模拟在此状态下结束。结果表明：尽管种群参数和竞争参数具有相同的规律，但由于幼虫随机沉降到底部，模拟实验之间存在较大差异。这意味着，如果重复次数很少，则可能得到与真值相反的结果。均势系统中两种植被覆盖面积平均相等，均势系统中两种植被覆盖面积平均相等。然而，在对峙系统中，掩护的变化比在偶数输赢系统中要小。竞争物种的盖度在极限值的1上发生灾难性的变化。即使是弱小的物种也会占据相当大的空间，如果存在强大的物种会抑制与弱小竞争的物种，即间接效应。种数从3种增加到10种，盖度的相对差异有减小的趋势。

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.