Japanese beech (Fagus crenata) forests are predicted to be decrease by global warming. Early stage of regeneration is important to sustain beech forests. Leaf expansion of beech begins earlier than that of other tree species. So that, under canopies of other tree species, light environment of forest floor is better than under the canopies of beech. Such place is called as phonological gap. Therefore, we intended to clarify the effects of environmental changes include light and temperature on beech seedlings by examining two questions using field manipulative experiment of warming. Q1: What is the effects of warming on beech seedlings? Q2: Do these effects differ depending on light environment?

We set beech seedlings in warmed and control plots under beech canopies, phonological gaps and forest opening sites. Different forms of open top chambers (OTCs) were used for this study. Mean daily and daytime air temperature were higher in the warmed plots compared to control plots: under forest opening sites, 0.52 deg and 0.92 deg higher, while under the beech canopies, 0.22 deg and 0.29 deg higher in October 2010.

Current year’s growth and bud length and defoliation phenology of beech seedlings were measured. We discuss about the response of beech seedlings to different air temperature and light environment.