SPECIAL ISSUE “ Protection and Restoration of Vegetation Damaged by Deer Grazing ” Seasonal impact of deer browsing on the demography of Fagus japonica seedlings in a cool-temperate forest

Severe browsing pressure from deer may have great effects on the regeneration dynamics of woody seedlings by affecting seedling mortality and seedling demography. This study quantified the seasonal impact of deer browsing on the relationship between seedling survival and the timing of seedling germination. We established a fenced deer exclosure in a cool-temperate forest in Chichibu that experienced browsing pressure from deer. Newly germinated seedlings of the dominant beech, Fagus japonica, were marked and monitored frequently in the fenced plot and outside the deer fence (open plot). To compare the demography of current-year seedlings, the effects of the timing of germination, light conditions, and total seedling density in each monitoring quadrat were analyzed considering their differences between the two types of plots. The survival rate at the end of the growth period was significantly lower in the open plot (2.0 %)thaninthe fenced plot (9.4 %), mainly because of deer browsing (73.8 % of the total mortality in the open plot). Intensive browsing was observed only during the early growth season, while damping off was the major cause of mortality in the fenced plot (79.0 % of total) during the middle season. Statistical analysis detected opposite effects in the open and fenced plots; early germination was disadvantageous and advantageous for survival, respectively. Seedling demography relating to the advantage of the timing of germination may change depending on the impact of deer browsing, which has clear seasonality.