2014 Volume 14 Pages 18-28
We investigated historical records (e.g. old diaries, historiography, and daily newspapers) and acquired phenological data series for autumn-tinted maple (Acer spp.) leaves in Kyoto, Japan. From the 10th to 21st centuries, we gathered 504 years of phenological data for maple leaves' autumn tints. A preliminary analysis suggested that the dates of the maple autumn tints were affected by the October mean temperature. Therefore, an attempt was made to reconstruct the October mean temperature in Kyoto by applying the phenological data for autumn tints of maple leaves. Autumn temperature series partially showed a pattern similar to springtime temperature series. A cooling trend over the 15th — 16th centuries and cool conditions in the late 17th and the early 19th centuries were detected in both the October and the March temperature series; however, October temperature change preceded March temperature change by about 10—20 years. This suggests that the time-lag of response of October temperatures in Kyoto to the solar variation may be smaller than that of March temperatures.