Construction of a Millennial-long Chamaecyparis Dendrochronology for Centrarl Japan

在日本中部的木索森林中，偶尔还能发现一些中世纪和早期现代的原木，它们在腐烂中幸存了几百年。它们的中世纪起源的真实性可以在许多巨大的Chamaecyparis树中找到，这些树在大约300年前重新生长在它们的顶部，并且仍然活着。在目前的工作中，挖掘了大约200个中世纪和早期现代起源的原木，并将其年代学与同一地区70个活蚤的250年现代年代学进行交叉比对，建立了一个800年的标准年代学，时间可追溯至公元1100年代。对该标准年代学与现代仪器气候记录的年代学分析表明，年轮宽度主要与生长前的冬季温度相关，其次与夏季降水相关之前的生长期。在此基础上，重建了日本中部近800年的气候，明确了中世纪暖期结束期、13世纪中期至19世纪中期的小冰期和持续至今的持续变暖趋势。将树木年代学与过去的火山爆发记录进行比较后发现，在这些使南极和格陵兰冰盖产生酸性沉降物的大型火山爆发之后，气温明显下降，这表明火山爆发持续了几十年，导致气候变冷。

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.