Changes in Opal Phytolith Concentrations of Bambusoideae Morphotypes in Holocene Peat Soils from the Pseudo-Alpine Zone on Mount Tairappyo, Central Japan

Abstract

Like many other nival mountains in Japan, Mount Tairappyo in the Mikuni Mountains (36°48′N, 138°49′E, 1, 984m a. s. l.) lacks the subalpine conifer forest zone. Instead of conifers, grasses cover large areas of slopes above the upper limit of montane broadleaf forest (1, 600-1, 700m a. s. l.). An examination of phytoliths from peat soils focused on understanding the Holocene landscape evolution, particularly for changes in Bambusoideae (mostly Sasa) grasses occupying the present-day subalpine zone. Bambusoideae grasses, which densely covered slopes in the early Holocene, would have begun to decline between 5, 600 and 4, 940 cal yrs BP. This situation seemed to have persisted until 1, 300 to 680 cal yrs BP, when Bambusoideae grasses began to recover. This change in grassland vegetation from the middle to late Holocene epoch was probably induced by variance of snowmelt timimg related to climatic variabilities.