Construction of a Millennial-long Chamaecyparis Dendrochronology for Centrarl Japan

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Logs of medieval and early modern origins survived from decay for some hundreds of years are still found sporadically in the Kiso Forests, Central Japan. The authenticity of their medieval origin is found in many huge Chamaecyparis trees regenerated on top of them some 300 years ago and are still mounted alive. In the present work some 200 such logs of medieval and early modern origin were excavated, and their dendrochronologies were crossdated against a 250-year-long modern chronology compiled from some 70 living Chamaecyparis individuals from the same area to establish an 800-year-long standard dendrochronology extending back into the 1100s A.D.An dendroclimatic analysis of this standard chronology with the modern instrumental climatic record revealed that the ring width is primarily correlated with winter temperature preceding growth and secondary with summer precipitation of the preceding growth period. Based on this relationship, the climate of central Japan was reconstructed for the past 800 years, in which the terminating phase of the medieval warm epoch, little ice age spanning from the mid 13th Century till mid 19th, and consistent warming trend continuing up to present were clearly identified.A comparison of the dendrochronology with the past records of volcanic eruptions showed definite decline right after such major eruptions that maked acid fallout in Antarctic and Greenland ice sheets, indicating climatic cooling by eruption which lasts for a couple of decades.