Are stored carbohydrates necessary for seed production in temperate deciduous trees?

1. Many tree species undergo large fluctuations from year to year in seed production, a phenomenon known as masting. The resource budget model, based on the assumption that abundant seeding in a masting year depends on the abundance of resources stored over several years, is a key hypothesis in explaining the mechanism of masting. But do masting species really need such long-term storage to produce a large seed crop? 2. To test this hypothesis, we studied the relationship between the carbon accumulation period for seed production, as estimated by radiocarbon (C-14) analyses, and the coefficient of variation of annual seed production in 10 canopy tree species in a temperate deciduous forest. These species differ widely in their reproductive intervals. 3. In all the species studied, the accumulation period was < 1.4 years before seed maturation. Moreover, without taking species or reproductive intervals into account, there was no significant correlation between the carbon accumulation period and the fluctuation of annual seed production; both remained at an even level. 4. Synthesis. Our results suggest that temperate canopy trees used photosynthates produced in the current and/or the previous year for seed production, regardless of reproductive intervals. It might therefore be necessary to reconsider the importance of stored carbohydrate resources for masting.