X—Ñ—§’n55i2jC133`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

 

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