Traditional calendar reveals the effects of climate change on phenology in the last 300 years in Japan

Background/Question/Methods

Global mean temperature has increased in the last 100 years. Many studies have suggested that climate change affected phenology of animals and plants. ”Climate change model” predicts that spring and summer phenology will become earlier and autumn phenology will delay by climate change. For example, the flowering date of cherry blossoms and the first arriving date of barn swallow have become earlier, and the leaf coloring has been delayed. To clarify the effect of climate change on the phenology of plants and animals, it is necessary to use data on temperature and phenology over several centuries. However, such kind of data is quite limited. In this study, we compared Traditional Calendar with that of present days which were collected by the Japan Meteorological Agency. Traditional Calendar listed phenological data in the old documents in 17th and 19th Century (Edo era). For the comparison, the phenology of 3 plants and 5 animals in Kyoto and 2 plants and 3 animals in Tokyo were selected. 

Results/Conclusions

The major results were: 1) most species showed a significant difference in phenological events between the two periods, 2) current phenological changes were larger than in the Edo era, 3) phenological changes were larger for animals than for plants, 4) the phenological changes of summer and autumn mostly followed the trend predicted by the climate change model, although the spring phenology showed mixed results, and 5) The maximum difference of phenological events observed between the two periods were evening cicada and maple. By comparing current phenology with that of 1600’s, this study clarified that phenology were influenced by climate change. The maximum difference of phenological event observed between the two periods was about a month. Because animals may have responded acutely than plants for temperature, the phenological changes were larger for animals than for plants. Barn swallow in Tokyo showed no significant difference, because barn swallows may be affected by temperature in staging post of migration.