Postglacial climate variability at the northern limit of the East Asian monsoon and its impact on environments and humans in the Hokkaido region, northern Japan

• Applicant: Dr. Christian Leipe
• Subject Area: Palaeontology ; Physical Geography
• Term: from 2015 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 274137614

• Final Report Year: 2018

Final Report Abstract

The findings of the project add substantial information on past environment and climate dynamics and human-environment interactions in the Northwest Pacific region. Results of a high-resolution palynological investigation supplemented by diatom, mineralogical, and geochemical studies of the chronologically well-constrained RK12 sediment core from Lake Kushu (Rebun Island) represent a regional key palaeoenvironmental record covering the late glacial–Holocene interval. The derived data outline climate changes on a long- and short-term scale, which partly correspond with major hemispherical or global-scale climate transitions/events. The multi-proxy record also highlights 3 main phases of lake basin development including a marshy phase, lagoon phase, and freshwater lake phase, the regional Holocene marine transgression maximum, and human impact on the lake system. The reconstructed palaeoenvironmental changes also coincide with transformations in the Hokkaido prehistoric cultural sequence, such as the onset of the Middle Jomon, the Middle/Late Jomon transition, the immigration of Okhotsk culture groups, and the establishment of the Classic Ainu culture. Discussion of potential impact of climate change on prehistoric cultural dynamics had been promoted by the analysis of the spatio-temporal distribution of archaeological sites in the Hokkaido region. The findings indicate dynamic changes in hunter–gatherer populations from the Upper Palaeolithic through the Neolithic/Jomon and Epi Jomon period to the historic Ainu period and support hypotheses on major changes in subsistence strategies, which coincide with identified shifts in climatic conditions. An extensive, well-dated archaeobotanical record from the Hamanaka 2 archaeological site (located close to Lake Kushu) in combination with the derived palaeoenvironmental reconstructions from the RK12 core provides detailed insights into the occupation history of hunter–gatherer populations and their impact on the local (Rebun Island) environment. Moreover, the obtained record of carbonised seed remains from Hamanaka 2 have generated a new perception of the subsistence strategies of Hokkaido’s prehistoric cultures, which have been long time regarded as classic hunter–gatherers. To our surprise, we recovered an abundant record of domesticated barley seeds, which, through direct radiocarbon dating, can be attributed to the Okhotsk culture. These findings are proof that this culture practiced both hunting/gathering and cultivation of domesticated plants representing the first scientifically documented example for this special form of hybrid subsistence in the early history of East Asia. Analysis of carbonised barley seed populations from the wider study region provides new information on the spread of barley through East Asia and illustrate that two barley phenotypes were introduced into Hokkaido via different routes.

Publications

• 2018. Vegetation change and human impacts on Rebun Island (Northwest Pacific) over the last 6000 years. Quaternary Science Reviews 193, 129-144
  Leipe, C., Müller, S., Hille, K., Kato, H., Kobe, F., Schmidt, M., Seyffert, K., Spengler III, R., Wagner, M., Weber, A.W., Tarasov, P.E.
  
• 2016. Spatio-temporal distribution of hunter–gatherer archaeological sites in the Hokkaido region (northern Japan): An overview. The Holocene 26(10), 1627–1645
  Abe, C., Leipe, C., Tarasov, P.E., Müller, S., Wagner, M.
  
• 2017. Barley (Hordeum vulgare) in the Okhotsk culture (5th– 10th century AD) of northern Japan and the role of cultivated plants in hunter–gatherer economies. PLoS ONE 12(3), e0174397
  Leipe, C., Sergusheva, E.A., Müller, S., Spengler III, R.N., Goslar, T., Kato, H., Wagner, M., Weber, A.W., Tarasov, P.E.
  
• Testing the performance of sodium polytungstate and lithium heteropolytungstate as non-toxic dense media for pollen extraction from lake and peat sediment samples. Quaternary International
  Leipe, C., Kobe, F., Müller, S.