森林立地55（2），133〜137 2013

Jpn J For Environ 55 (2), 133―137, 2013

 

A bagging experiment to evaluate the effect of predispersal

predation exclusion on nut viability in beech (Fagus crenata Blume)

 

Hideyuki Ida¹, Masanobu Hotta² and Yasuo Ezaki³

¹Institute of Nature Education in Shiga Heights, Faculty of Education/Institute of Mountain Science, Shinshu University

²Nagano Environmental Conservation Research Institute

³INES, University of Hyogo/Hyogo Park of the Oriental White Stork

 

We conducted an experiment to evaluate the effectiveness of preventing predispersal predation on nut viability in beech (Fagus crenata Blume) by bagging a single canopy tree in an old-growth stand of central Japan over two consecutive years with different nut production. To prevent predation on predispersal nuts, the bagging treatment began in mid June of both years. Seed trap sampling of fallen nuts and direct sampling of cupules were also conducted to monitor seasonal changes. Although viable nuts were less productive in the sample beech than in the surrounding beech stand, the bagging treatment increased the proportion of viable nuts from the sample beech by approximately eight fold in the first year (from 4.9% to 41.3%) and five fold (from 2.4% to 12.5%) in the following year. Thus, at an individual level, predator exclusion by bagging increased the percentage of viable nuts by reducing predispersal predation. The results of this experiment confirm that predispersal insect predation is a major factor controlling the viable nut rate in beech.

Key words : bagging, beech forest, Fagus crenata, predispersal predation, seed production

 

井田秀行・堀田昌伸・江崎保男：ブナ（Fagus crenata）堅果の散布前捕食の影響：袋掛け実験による評価．森林立地55：133-137, 2013.