Review: Phytogeography and history of Japanese beech forests: Recent advances and implications for vegetation ecology

Abstract

AbstractIn this review, the phytogeography and history of Japanese beech (Fagus crenata Blume and F. japonica Maxim.) forests are re‐examined in light of recent phytogeographical and palaeobotanical research advances. I explain the floristics and the climatic and geological contrasts between Japanese beech forests on the Sea of Japan side and the Pacific side of the Japanese archipelago. We also review recent studies on the origin of dwarf evergreen shrub species occurring along the Sea of Japan. The old scenario that these dwarf evergreen shrub species diverged directly from counterpart species occurring on the Pacific coast of Japan is no longer supported. We propose more intricate speciation processes, including phylogenetic relations to extant Chinese species and inter‐species hybridization. We also review the results of recent palaeobotanical studies of forests on the Japanese islands in the Quaternary. The long persistence of beech forests through glacial/interglacial cycles of the Quaternary—with repeated spread and contraction of the geographical range—is confirmed. In addition, we briefly explain the phytosociological classification system of the Japanese beech forest and the geographical ranges of each vegetation type. We review studies of the geographic distribution of F. crenata and F. japonica at the population level, highlighting the need for further ecological and genetic studies of population dynamics near the range limits to understand historic migration processes better.