Before revision:  3. The model suggests that establishment-longevity tradeoff, in which annuals have competitive advantage over perennial seedlings, is a necessary condition for equilibrium priority effects. Equilibrium priority effects also require low fecundity in both annuals and perennials and small fitness differences, as determined by their relative fecundity, survival probability, and competitive ability at the seedling stage.
After revision:  3. The model suggests that establishment-longevity tradeoff, in which annuals have competitive advantage over perennial seedlings, is a necessary but not sufficient condition for alternative stable equilibria that require also low fecundity for both species. An analytical approximation of our simulation model demonstrates that alternative stable equilibria are driven by demographic stochasticity in the number of seeds arriving at each establishment site. This site-scale stochasticity is only affected by fecundity in both annuals and perennials and small fitness differences, as determined by their relative fecundity, survival probability, and competitive ability at the seedling stage.