Spatial patterns of vegetation of Japan

Yukito NAKAMURA
1 Tokyo University of Agriculture, Tokyo, Japan

One of the features of vegetation patterns in Japanese archipelago is a noticeable difference between the areas adjacent to the Sea of Japan and Pacific Ocean. Within the cool temperate zone occupied by vegetation belonging to the Fagetea crenatae, there are two different alliances. Saso-Fagion crenatae is characteristic to the Sea of Japan side and Sasamorpho-Fagion crenatae to the Pacific side. In the Vaccinio-Piccetea region which represents in Japan the altitudinal belt of conifer forests vicarious to boreal vegetation, the Abietetum mariesii predominates on the Sea of Japan side while the Abietetum veitchio-mariesii occurs on the Pacific side of archipelago. Due to heavy snow accumulation in winter time in the Sea of Japan side, the edaphic climax vegetation belonging to the class Betulo- Ranunculetea is most developed in this area. The latter vegetation type was formed in at the end of period of Pleistocene maximum when the snowy climate was developed in the eastern part of Japan. Before that, because the considerable lowering of sea level during ocean transgression blocked the Tsushima warm current from entering the Sea of Japan, there was a cold episode of climatic history that characterized by predominance of the continental climate in the coastal areas of Sea of Japan. Vegetation reconstruction for the late Pleistocene showed the occurrence of micro- and macrofossils of Picea maximowiczii, P. koyamae, the relatives of Picea obovata. Nowadays, these species occur in isolated areas of Yatsugatake, Chubu district. At the end of Pleistocene Maximum and early Holocene, 13,000-10,000 years BP, with the Sea level rise the Tsushima Sea current entered the Sea of Japan and cold continental climate in the coastal areas in several hundred years has changed to cool temperate with heavy-snow in winters. Japanese cedar, Cryptomeria japonica forests spread in colline belt and Fagus crenata forests belonging to Saso-Fagion crenatae in montane belt. Continental conifer forests of Picea maximowiczii and P. koyamae disappeared from coastal areas and were replaced here by Abies mariesii forests belonging to the Abietetum mariesii and Betula ermanii forests in combination with tall forbs communities.



2012 Organizing Committee