ANNUAL VARIABILITY IN SEED PRODUCTION BY WOODY-PLANTS AND THE MASTINGCONCEPT - REASSESSMENT OF PRINCIPLES AND RELATIONSHIP TO POLLINATION AND SEED DISPERSAL

By analyzing 296 published and unpublished data sets describing annual variation in seed output by 144 species of woody plants, this article addresses the following questions. Do plant species naturally fall in to distinct groups corresponding to masting and nonmasting habits? Do plant populations generally exhibit significant bimodality in annual s eed output! Are there significant relationships between annual variabi lity in seed production and pollination and seed dispersal modes, as p redicted from economy of scale considerations? We failed to identify d istinct groups of species with contrasting levels of annual variabilit y in seed output but did find evidence that most polycarpic woody plan ts seem to adhere to alternating supra-annual schedules consisting of either high or low reproduction years. Seed production was weakly more variable among wind-pollinated taxa than animal-pollinated ones. Plan ts dispersed by mutualistic frugivores were less variable than those d ispersed by either inanimate means or animals that predominantly behav e as seed predators. We conclude that there are no objective reasons t o perpetuate the concept of mast fruiting in the ecological literature as a shorthand to designate a distinct biological phenomenon. Associa tions between supra-annual variability in seed output and pollination and seed dispersal methods suggest the existence of important reproduc tive correlates that demand further investigation.