Statistical Analysis of the Relationship between Changes in Plant Phenology and Daily Mean Air Temperature in Japan under Climate Change

抄録

　This study was conducted to verify the relationship between the shifts in plant phenology and changes in air temperature over a 40-year (1961-2001) period in Japan. Daily mean air temperature and annual phenological data (1961-2001) from 101 meteorological stations of the Japan Meteorological Agency were used in this study. The phenological data consists of both springtime phases such as flowering and full flowering, autumn phases such as leaf coloring and leaf fall of trees.
　We considered influences of daily temperature being just closed to the date of phenological events, therefore the anomalies of daily mean air temperature between 1961 and 2001 were used. The length of periods during which air temperature affects phenological events was determined by maximization of the correlation coefficients between the cumulated anomalies prior to the date of each phenological event and to the data of each phenological event from 1961 to 2001 by the linear regression.
　From the 16 types of plant phenology, the lalgest was 0.88 for Prunus yedoensis Matsum. flowering. The length of periods with maximum correlation coefficient differed from plant phenology. Results of the analysis suggest that some phenological trends reflected responses to climate change in Japan.