THE REGENERATION OF PIONEER TREE SPECIES UNDER BROWSING PRESSURE OF SIKA-DEER IN AN EVERGREEN OAK FOREST

The effects of Sika deer (Cervus nippon) browsing on the regeneration of pioneer species were studied in relation to canopy gaps in a warm t emperate evergreen oak forest in Kasugayama, Nara City. Four study sit es, three in canopy gaps and one under a closed canopy, were selected and each divided into fenced and unfenced plots. Under the dosed canop y, seedlings of all the pioneer species died irrespective of browsing pressure. However, in the canopy gap sites, seedlings of the pioneer s pecies could establish and grow well. The seedling survival ratio in t he fenced plots in the canopy gaps was > 60% 1 year after germination. However, in the unfenced plots, only < 20% of the seedlings survived 1 year, with all dying within 3 years after germination. Thus, the reg eneration of pioneer trees in this forest was strongly inhibited by de er browsing. Successful regeneration of a pioneer, Zanthoxylum ailanth oides, occurred for several years even after two major wind disturbanc es during the past 90 years. This may be due to less browsing pressure from the deer.