Fruit fall in five warm- and cool-temperate forests in Yakushima, Japan

Quantification of fruit fall is the only way to compare fruit food availability among different studies. This study aims to reveal the general characteristics of fruit fall in temperate forests, which should offer indispensable information for using fruit fall data as food availability for frugivores. Fruit fall in three warm-temperate and two cool-temperate forests on Yakushima, an island in southwestern Japan, were studied for two years in one cool-temperate plot of 50 m×50 m in size and for four years in other plots of 100 m×50 m in size. The elevations of the plots ranged 170-1200 m a.s.l. Fruit fall was highest in the lowland forests (599 and 564 DW kg·ha^-1·year^-1 and lowest in the mid-elevation forest (198 DW kg·ha^-1·year^-1). Fleshy fruits and food-fruits for Japanese macaques constituted 3-37% and 4-87% of the total fruit fall, respectively. When only fleshy-fruit fall was compared, it was higher in the western lowland forest (222 DW kg·ha^-1·year^-1) than in any other forests (9-66 DW kg·ha^-1·year^-1). The pulp of fleshy fruits, presumably the edible parts for frugivores, was only 1.1-12.7% of the total fruit fall. The edible parts for Japanese macaques constituted 3-54% of the fruit fall, showing a high value where acorns are abundant. Half of the fruit-fall biomass consisted of only one or two nonfleshy-fruited species, which are usually dominant in many other temperate forests, such as Quercus and conifers. These variations agreed with the variations in occurrence of frugivorous (such as Japanese macaques).