Based on the importance of conserving endangered species and of long-term ecological research, the overall objective of the extensive study was designed to continuously monitor the relative abundance of large mammals and acorn production. The main purpose was to understand the complicated interaction between Formosan black bears (Ursus thibetanus formosanus) and the oak forest ecosystem in Yushan National Park. We also studied the vegetation ecology of the oak-dominant forest of Daphan. The differentiation of vegetation was influenced by altitude, direct light sky space, slope, and topography. Two-way indicator species analysis was used for classification of vegetation types, and revealed 3 types: Lithocarpus harlandii－Embelia lenticellata, Rhododendron latoucheae－Quercus stenophylloides, and Glochidion rubrum－Quercus glauca. The third type was dominant, composing 29 of the 31 sampling stands. The important value index of the important bear food, Quercus glauca, was 27.5%, much larger than any other tree species (all< 20%). While there was enormously high level of seed predation pressure on acorns of Q. glauca in our study area, the high rate (60.8%) of sprouting suggested sprouting could play a potential role in the forest succession process.