Masting behavior of Fagus crenata in northern Japan: spatial synchrony and pre-dispersal seed predation

Abstract

An 11-year study of total seed and seed production in five natural Japanese beech ( Fagus crenata) forests in Hokkaido, northern Japan, estimated the spatial synchrony of masting and examined whether variation in annual total seed production resulted in fluctuations in pre-dispersal seed-predator populations. We found less synchrony in total seed production than in sound seed production among sites. The coefficients of variation of sound seeds (1.3–2.1) were greater than those of total seeds (0.8–1.3) in each site. Pre-dispersal seed predation by moth larvae has a major influence on sound seed production in F. crenata. To test whether variation in annual total seed production resulted in fluctuations in predator populations, we examined the relationship between the ratio of current year total seed production to previous year total seed production, and the percentage of pre-dispersal seed predation in the current year. We found a negative correlation between insect predation and the ratio of current to previous year total seed production, suggesting that poor total seed years resulted in a decrease in predator populations. The pre-dispersal seed predators of F. crenata appeared to cope well with up to 10-fold variation in total seed production between years, but when the total seed production exceeded 20 times that of the prior year, the predators were satiated.