Japanese Journal of Historical Botany

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The vegetation history of the pseudo-alpine zone was reconstructed based on pollen and phytolith analyses of Holocene soil collected from an outcrop on the Mt. Yumori in the Akita Komagatake area. The outcrop consisted of many thin soil layers and thick Holocene tephras that erupted from the Akita Komagatake volcano. To determine the past vegetation of each formation period, we investigated pollen and phytolith assemblages in the soil using the tephras as time markers. From ca. 9000 to ca. 7600 yr BP, vegetation was sparse like a volcanic desert. After ca. 7200 yr BP, some herbaceous species including Sasa colonized near the outcrop, and a thick community of wet herbaceous species grew. By ca. 5400 yr BP, as the snow fall increased with the postglacial climate change, Sasa near the outcrop disappeared. Pinus pumila spread around the outcrop by ca. 3600 yr BP, and herbaceous vegetation without Sasa continued nearby. After ca. 2200 yr BP, Sasa again colonized near the outcrop, and herbaceous vegetation thrived. From ca. 1800 yr BP to the present, herbaceous species declined, and the vegetation became dominated by Sasa grassland and shrubs.

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