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With a warming climate, many temperate plants may not meet their winter chilling requirements and may not flower
normally in spring. This effect may represent a particular problem for the culturally important Tokyo cherry (Cerasus
×yedoensis ‘Somei-yoshino’) at the southern limits of its range in Japan. We investigated the flowering period and dor-
mant bud development of Tokyo cherry at study sites at the southern limits of the plant’s range in Kagoshima Prefecture,
Japan and at sites in cooler parts of the plant’s range in Kumamoto Prefecture, Japan. We analyzed long-term observa-
tions collected at two sites during the years 1965–2024, and more detailed observations collected at 14 sites during the
years 2021–2024. Cumulative chill units (cCU), a measure of winter chilling, showed strong negative correlations with
full bloom date and flowering intensity, with milder winters associated with delayed spring flowering and lower propor-
tions of flowers open at peak flowering. Trees experiencing mild winters with cCU values of less than 1,500 tended to
exhibit development disorders for flowers and leaf buds. These effects were particularly pronounced in very mild winters
with cCU values of less than 1,000. This study highlights how the lack of sufficient winter chilling threatens the flower-
ing display of this culturally important tree at the southern edge of its range. Such threats will become more frequent
and widespread as the climate continues to change. Managers need to consider alternative strategies to maintain flower
displays during cherry blossom festivals, such as planting species with lower winter chilling requirements.
Research papers (academic journals)
