Mast seeding or masting refers to intermittent and synchronous production of large seed crops in a population of perennial plants. It is generally accepted to be regulated by internal resource level. However, the latest studies demonstrated that seed production relies exclusively on current-year photo-assimilate and not on stored carbohydrate. Therefore, the role of resource level in determining the floral initiation is unclear yet. Here, we monitored seasonal variations in three key flowering genes, internal resources (carbohydrate and nitrogen) and soil nutrients from both fruiting and non-fruiting trees of mature Fagus creneta forests. The three genes are FLOWERING LOCUS T in leaves, LEAFY and APETALA1 in winter buds. Floral gene expressions were related to flowering rate at both branch and individual levels and highly variable between branches when flowering rate in an individual tree was low. Available nitrogen in soil fluctuated significantly seasonally and yearly and influenced by soil temperature. Available phosphor was extremely low in comparison with other temperate forests. Plant internal resource dynamics is under analysis and we will report how internal resource level is related within gene expresses and influenced by soil nutrient supply.