Читать книгу Ecology - Michael Begon - Страница 125

We have seen that there are typical patterns in the effects of intraspecific competition on birth and death, and these are summarised in Figure 5.12.

Figure 5.12 Density‐dependent birth and mortality rates lead to the regulation of population size. When both are density dependent (a), or when either of them is (b, c), their two curves cross. The density at which they do so is called the carrying capacity (K). Below this the population increases, above it the population decreases: K is a stable equilibrium. However, these figures are caricatures. The situation is closer to that shown in (d), where mortality rate broadly increases, and birth rate broadly decreases, with density. It is possible, therefore, for the two rates to balance not at just one density, but over a broad range of densities, and it is towards this broad range that other densities tend to move.