Tree regeneration can be limited by the number of fruit produced by mature trees. Fruitproduction may inuenced by tree size, soil nutrient availability, and competition with neighbors.In addition, synchronized reproduction in masting events may increase reproductivesuccess of individuals. Because of dierences in soil characteristics and biotic communities,there may be dierences in the factors that aect fruit production in tropical versus temperatespecies. Fruit production was individually measured for 3600 trees of 17 tropicalspecies in La Selva, Costa Rica, and 10 temperate species in the Manistee National Forest,Michigan, USA. In both regions, tree size was the dominant inuence on fruit production,with larger trees producing more. In addition, soil nutrient availability had little eect onfruit production in both regions. In tropical species, the presence of larger neighboringtrees reduced fruit production. This eect is consistent with competition for light, and maysuggest that carbon balance of individuals is important for reproduction in these species.In temperate species, I combined individual fruit production measurements with longterm seed and seedling density data to assess the synchrony of individuals during mastingevents. In two species, Acer saccharum and Fagus grandifolia, I found that a small subset ofindividuals fruited more often and were responsible for a large proportion of fruit productionin their populations. In contrast, in Tila americana dierent subsets of individuals wereresponsible for dierent masting events. These results highlight the importance of consideringindividual trees in studies of masting and environmental eects on reproduction.
Read
