CR 34:99-104 (2007)  -  doi:10.3354/cr034099

ABSTRACT: Although it is likely that winter flowering of various plant species has been influenced by recent climate change, previous phenological analyses have not focused on flowering phenology in winter. In Japan, the Japanese apricot Prunus mume historically flowers during the cold months of winter from January to March. I used a continuous dataset of the flowering date at 32 sites in various regions of Japan from 1953 to 2005. Over the course of this period, the flowering date of apricots has advanced, with a notable shift in regimes between 1953–1989 and 1990–2005. The correlation results show that mean winter air temperature significantly affected the flowering date of the apricots at all of the sites, but snowfall was not correlated with the flowering date at 30 out of 32 sites. The difference between the mean flowering dates of 1953–1989 and 1990–2005 was correlated with the correlation coefficient between the flowering date and air temperature. Winter flowering of Japanese apricot has been influenced by recent climate change, especially by drastic climate-related shifts in the timing of key processes.

KEY WORDS: Climate change · Snowfall · Air temperature · Regime shift · Dynamic factor analysis