With This Technology, You Can Align Your Japan Trip Plan To See The Cherry Blossom Season
Springtime in Japan, with its iconic cherry blossoms, known locally as sakura, captivates both residents and visitors from around the world. The blossoming begins in Kyushu, the southern part of Japan, and sweeps northward to Hokkaido. Among the varieties, the Somei Yoshino cherry trees are particularly revered. These cloned trees burst into a synchronized display of white and pink flowers, marking a celebrated moment of natural beauty across the country.
However, the predictive tracking of Somei Yoshino's bloom has become challenging due to climate change affecting the trees' flowering schedule. Traditionally, months ahead of the bloom, forecasts are eagerly awaited by those planning to partake in the festivities and by locals preparing for the seasonal celebrations.
Researchers at Kyushu University, in collaboration with the Forestry and Forest Products Research Institute, have made strides in understanding these changes by developing a new model. Their work focuses on the gene activity within the cherry tree buds to forecast when they will emerge from dormancy. Published on September 19 in the journal Plants, People, Planet, this research not only aims to refine flowering predictions but also sheds light on how climate change might threaten these cherished blooms, especially in Japan's warmer regions.
The study reveals that the awakening of cherry tree buds from dormancy is a complex process, dependent on two phases: endodormancy and ecodormancy. The former requires a period of cold weather to conclude, while the latter needs warmth to transition. Atsuko Miyawaki-Kuwakado, a leading researcher on the project, notes, "This need for both cooling and heating means that flowering times can be very unpredictable," depending on seasonal temperatures.
The breakthrough came when the team, led by Miyawaki-Kuwakado and Professor Akiko Satake, decided to delve into the molecular level of the buds. They hypothesized that by examining the internal changes within the buds, they could identify the precise moment endodormancy concludes. Their research showed that as winter progresses, the expression levels of a gene named DAM4 decrease, signaling the end of endodormancy after about 61 days of temperatures below 10.1°C.
By monitoring Yoshino cherry trees across Japan—from Fukuoka in the south to Hokkaido in the north—the team documented the gene activity patterns throughout the seasons. They discovered that DAM4 plays a crucial role in maintaining dormancy. "We saw that at the start of winter, DAM4 was highly expressed, but as each day passed with temperatures below 10.1°C, the activity of DAM4 decreased. Once below a certain threshold, the buds awoke from dormancy and flowered when experimentally heated," Satake explained.
This gene-focused model enables the team to predict the flowering of Yoshino cherry trees based on the activity of DAM4 and historical temperature data. Over the years 1990–2020, they observed that endodormancy's conclusion has been delayed by approximately 2.3 days per decade. The findings underscore the impact of fewer cold days due to global warming, particularly in Japan's southern regions, where the cherry blossoms are a significant cultural and tourist attraction.
Such insights allow forecasters to refine their predictions on when the cherry blossoms will bloom. The team is also looking to further adapt their model to anticipate the effects of climate change on these flowering patterns. "Without sufficient cool days over winter, endodormancy cannot break and Yoshino buds cannot flower," Miyawaki-Kuwakado emphasized. The researcher highlights the importance of predicting global warming's impact to develop strategies that could mitigate its effects on Japan's cherished cherry blossom tradition.
The research by Kyushu University and the Forestry and Forest Products Research Institute marks a significant advancement in understanding how climate change is affecting Japan's iconic cherry blossoms. Through their innovative approach to predicting bloom times, there is hope for preserving this important aspect of Japanese culture and natural beauty.
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