Both seedling banks and specialist seed predators promote the evolution of synchronized and intermittent reproduction (masting) in trees

1. Conditions leading to the evolution of masting (intermittent and synchronized reproduction of trees) are examined. According to the dynamics of the resource reserve of individuals, reproductive investment is the proportion of investment in flowers with coefficient k. If k evolves to sufficiently large values, trees show a large between-year fluctuation in the seed crop even in a constant environment (masting). 2. Our assumptions are: the forest consists of many sites, each occupied by a single canopy tree. After a canopy tree falls, the vacant site (gap) becomes available for recruitment. 3. Masting never evolves if all vacant sites are filled by individuals from seeds produced in the same year, despite the fact that trees reproducing intermittently enjoy a higher pollination success than trees reproducing annually. 4. Masting can evolve if some seedlings survive for several years, forming a seedling bank on the forest floor, where seeds produced in different years compete for gap acquisition. In this case, the disadvantage of intermittent reproduction is compensated for by seedlings and the benefit of pollen limitation dominates. 5. We also study the effect of specialist seed predators. In the complete absence of seed bank or seeding bank, masting never evolves even in the presence of seed predators. If some seedlings survive for multiple years, seed predators can promote the evolution of masting. 6. Synthesis. Both seedling banks and specialist seed predators promote the evolution of masting. However, the presence of seed predators can work only when some seedlings can survive more than 1 year. The regeneration process of forests must be considered when the evolution of the reproduction of plants is discussed.