Japanese Cherry Trees at Risk
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The Japanese cherry blossom festival is one of the most important cultural events in Japan and is now known worldwide. Every year, it attracts tourists from many countries, eager to plan their trips well in advance just to witness this spectacle. And yet, recent research shows that global warming could compromise it, particularly in southern Japan.
The problem concerns the Tokyo cherry tree (Cerasus ×yedoensis ‘Somei-yoshino’), the symbolic variety of Hanami. Like many plants from temperate regions, this cherry tree needs to maintain its winter chilling requirement, that is, to accumulate a certain amount of cold in order to correctly break dormancy and then respond to spring warmth with regular flowering. If winters are too mild, this chilling requirement is not met and the plant’s development may be altered.
To understand how far this phenomenon is already underway, researchers compared sites at the southern limit of the cherry tree’s range in Kagoshima Prefecture with colder sites elsewhere in Japan. They used both historical data collected by the Japan Meteorological Agency between 1965 and 2024 and detailed observations conducted between 2021 and 2024 at 14 sites, monitoring flowering and bud development. To estimate available winter cold, they calculated cumulative chill units, that is, a measure of the amount of low temperatures accumulated during winter.
The results show that when this accumulation of cold drops below a certain threshold, the flowering of the Tokyo cherry tree is strongly compromised. In the warmest sites, especially in Kagoshima, full bloom can be delayed by more than a month. In addition, full bloom and synchrony are lost. This means that, on the one hand, not all buds are able to open and, when they do, they do not open at the same time, making the visual display less impressive. Added to this are numerous abnormalities, such as bud drop, degenerated inflorescences, and leaf problems, which reduce the plant’s ability to produce energy and form new buds for the following year.
According to the authors, these anomalies will become increasingly frequent as climate warming advances into other regions. This represents not only an ecological problem, but also a cultural and economic one, because cherry blossom flowering is an integral part of Japanese identity and seasonal tourism. For this reason, the researchers suggest evaluating the introduction of varieties or species with lower chilling requirements, in order to preserve the spectacle of flowering in the future.
See You Soon and Good Science!
Source Pic by ipstar000 (Pixabay)
