Vegetation changes around the last glacial maximum and effects of the Aira‐Tn ash, at the Itai‐Teragatani site, central Japan

Abstract

AbstractOn the basis of fossil pollen, plant macrofossils and fossil wood, vegetation existing around the Itai‐Teragatani Site between 26000 and 20000 yr ago was reconstructed. On the upland, there were mixed forests of conifers and deciduous broad‐leaved trees throughout the studied period. The forests consisted mainly of Pinus subgen. Haploxylon and Quercus subgen. Lepidobalanus, together with Tsuga, Cryptomeria and Ulmus‐Zelkova. In the wetland, there were stands of Betula and Alnus in grassland consisting of Cyperaceae, Gramineae, Lysichiton, Thalictrum, Sangusiorba, Umbelliferae and Compositae. The vegetation changed three times during the studied period. The first change, which occurred prior to the fall of the Aira‐Tn ash, was characterized by an increase in Abies, Pinus subgen. Haploxylon and hygrophytes, and a decrease in Cryptomeria and Alnus. This is considered to reflect a cooler climate, and expansion of grassland. The second change was caused by the fall of the Aira‐Tn ash, which caused serious damage to the vegetation. Many taxa, except for Alnus, Cyperaceae and Lysichiton, decreased or vanished after the ash fall. The third change was the process of recovery after the damage. The regenerated forests differed from those before the ash fall. With the regeneration conifers and Artemisia increased. This seemed to reflect the changes in climate and ground conditions caused by the accumulation of the ash.