Within–population spatial synchrony in mast seeding of North American oaks

Mast seeding, the synchronous production of large crops of seeds, has been fre-quently documented in oak species. In this study we used several North American oak data-sets to quantify within-stand (10 km) synchrony in mast dynamics. Results indicated that intraspecific synchrony in seed production always exceeded interspecific synchrony and was essentially constant over distances ranging from 100 m to 10 km. Asynchrony between species was at least partially attributable to differences in the endogenous dynamics in seed production caused by the varying numbers of years (1 or 2) required to mature seeds. Similarly, the magnitude of intraspecific seed production synchrony was related to intraspecific variation in endogenous dynamics; this intraspecific variation could be caused by spatial variation in habitat conditions. These results indicate that both interspecific and intraspecific variation in the endogenous processes generating variability in seed production may influence the magnitude of spatial synchrony in total (all species) mast production. Such findings may be of significance to understanding interactions between syn