OOS 62-4 - Time to reproductive onset and subsequent annual variability in the seed production of serotinous and non-serotinous conifers

There are two generalizations about serotinous species that rely almost entirely on anecdotal information. The first is that they produce fruit or ovulate cones earlier than non-serotinous taxa. The second generalization is that serotinous species have less variation (“masting”) in their subsequent temporal seed production schedule than do others. Augmenting the few publications available with new data for a large number of species, we show that indeed serotinous species are (1) remarkably uniform in their annual production, and (2) achieve reproductive status at an age (or size) two to three times younger (or smaller) than do their non-serotinous competitors. Further, onset is determined by plant size rather than age. Subsequently, serotinous species have far less temporal variation in their annual seed production than do non-serotinous species. For both traits, conflicting selection pressures are discussed, as well as the interaction of time to first reproduction and the frequency of stand-replacing fire.