Adaptations of the Early Jomon people in their settlement relocation to climate change around Lake Mikata, Central Japan

The people who lived at the Torihama midden (Torihama settlement) site near Lake Mikata in Central Japan abandoned it after a major landslide ca. 5800 cal. bp, when they relocated their settlement to Taino, north of Shiiyama Hill. Two hundred years later, people abandoned the Taino settlement, and relocated to new settlements at Yuri and Kitadera, south of Shiiyama Hill. This study uses pollen analysis of an MK91 core from Lake Mikata and climate reconstruction through the modern analogue method using Polygon 2.4.4 software to understand the environmental conditions at the times these settlements were abandoned. The sediment from 356 cm to 458 cm, corresponding to 7300 cal. bp to ca. 5100 cal. bp, was analysed. The vegetation was dominated by Cryptomeria japonica (Japanese cedar) throughout the period. When the landslide occurred ca. 5800 cal. bp, precipitation and the risk of landslides were high. Taino, located on a gentle slope, was less vulnerable to landslide than Torihama. In the sediment covering the period after ca. 5600 cal. bp, the percentages of Cryptomeria pollen and the pollen flux of all pollen taxa decrease. Precipitation was lower, and the annual mean temperature at that time dropped to under 10 degrees C. The cold, dry climate led to the abandonment of the Taino settlement, with its strong winter north winds, and the relocation of the settlement to the warmer south side of Shiiyama Hill.