Does the early blooming of cherry blossoms indicate climate and ecological crises?

The cherry blossom season has arrived again. Monitoring in Japan has found that the blooming period of cherry blossoms is showing an early trend. What is going on? What factors determine the early or late blooming?

Compiled by New Media Editor Fang Yongzhen

March and April are the seasons when cherry blossoms are in full bloom. Cherry blossoms are widely planted all over the world because they are very ornamental. In fact, cherry blossoms are not a single flower, but a general term for many types and varieties.

Speaking of cherry blossoms, Japan is the most famous. my country also has a large area of ​​cherry blossom planting, and there are many places to enjoy cherry blossoms. For example, Beijing Yuyuantan Park, Hubei Wuhan University, Qingdao Zhongshan Park, etc. are all quite distinctive.

▲On March 28, in Tokyo, Japan, local cherry blossoms were in full bloom and citizens were visiting to enjoy them (Photo source: Global Times)

▲The cherry blossoms in Beijing's Yuyuantan Park are in full bloom, attracting tourists to enjoy the cherry blossoms in spring (Photo source: Beijing Daily Client)

▲On March 14, cherry blossoms bloomed on the campus of Wuhan University in Hubei Province, attracting teachers and students passing by to stop and watch. (Photo source: Guangming.com)

○ ○ ○

Flowering period is trending earlier due to climate warming

In Japan, cherry blossoms are designated as the national flower. The Japan Meteorological Agency announced on March 27 that cherry blossoms in the center of Tokyo and Fukuoka City are already in full bloom. Although the cherry blossoms in the two places are in full bloom five days later than in 2021, they are four days earlier than in previous years. Starting from mid-March this year, there were more days with temperatures exceeding 20 degrees Celsius, which caused the cherry blossoms to bloom earlier than in previous years.

▲In early March, Japan Weather News Company released this year's cherry blossom opening time forecast (Photo source: People's Daily Online - Japan Channel)

Japan, which has a tradition of cherry blossom viewing, has maintained the habit of recording the "peak" day of cherry blossoms every year (when 70% of the cherry blossoms have bloomed). Since 812 AD, Japan has recorded more than 730 cherry blossom seasons, which is the most complete and longest flower season record in the world.

It is worth noting that in 2021, the cherry blossoms in Kyoto, Japan, set a record for the earliest blooming period in 1,200 years. Many cities in Japan reached their "peak" in late March of that year. According to Yasuyuki Aono, a researcher at Osaka Prefecture University, the peak of cherry blossoms in Kyoto has hovered in mid-April for hundreds of years, and has been approaching early April since the beginning of the 19th century, but it is still rare to see them in March.

▲For thousands of years, the fluctuations in the "peak" day of cherry blossoms in Kyoto, Japan have been deeply affected by climate change. (Image source: CNN/International Journal of Biometeorology)

Cherry blossoms are very sensitive to temperature, and temperature changes are one of the important factors that advance or delay the flowering period. Some analysts believe that the overall trend of cherry blossoms entering the blooming period is getting earlier and earlier, and high temperatures from the two major sources of urbanization and climate change are the main factors. Officials from the Japan Meteorological Agency also said that the early blooming of cherry blossoms is "very likely" due to global warming.

Cherry blossoms blooming earlier and earlier may indicate a more serious climate and ecological crisis. Dai Peiquan, assistant professor of the Earth System Science Program at the Chinese University of Hong Kong, explained, "Plants and insects rely heavily on each other for survival, and both use the environment as a criterion to adjust different stages of their lives, but they respond to environmental changes at different paces. Climate warming is disrupting all of this. Insects may not be ready yet, and plants may bloom, which will result in insects not being able to obtain enough food sources from plants, and plants not having enough insects for pollination and reproduction."

Against the backdrop of global warming, the impact of climate change is not limited to cherry blossoms. Experts point out that the same phenomenon has also occurred in many agricultural and cash crops, which has also caused problems for food security and farmers' livelihoods.

○ ○ ○

When to bloom is closely related to accumulated temperature

Research has found that plant growth is closely related to meteorological conditions, especially temperature. The temperature here is not simply a certain temperature at which the plant will bloom, but is closely related to the cumulative temperature (also known as "accumulated temperature"). When the accumulated temperature reaches a certain threshold, the plant enters the initial flowering period.

According to the growth habits of cherry blossoms, their buds usually form in the summer of the previous year, but they do not open immediately. The leaves of the cherry blossom tree will transport a dormant substance to the buds, causing them to enter a dormant state. After experiencing the low temperatures in autumn and winter, as the temperature rises in spring, the buds break the dormant state and gradually bloom.

The early or late flowering of cherry blossoms is related to the temperature in early spring. The higher the temperature in early spring, the earlier and faster the budding of cherry blossoms. Generally speaking, cherry blossoms begin to sprout when the daily average temperature is around 10℃, start to bloom when it is around 15℃, and the new shoots grow fastest when it is above 20℃. When it is below 5℃, the leaves begin to fall and enter dormancy.

▲In 2019, Wuhan University Weibo posted a picture of cherry blossoms blooming in October. This happens almost every year on some plants. (Image source: Screenshot of Wuhan University Weibo)

As long as the environmental conditions are suitable, some cherry blossoms will bloom in autumn. Du Wei, a teacher at the School of Life Sciences of Wuhan University, said that it is common for plants to bloom in the opposite season. Once the appropriate environmental factors induce the differentiation of flower primordia, coupled with suitable water and nutrient conditions, it is easy to bloom in the opposite season. Light plays an important role in plant flowering. The length of light in spring and autumn is sometimes very similar, so it can lead to misjudgment of plants and cause this situation, but most of them will not be like this.

The flowering period of cherry blossoms is very short, from blooming to withering, it only takes 7 days, and the whole cherry tree only takes about 2 weeks from blooming to withering. If the temperature drops after the flowers bloom, the flowering period will be extended; if there is strong wind or rain, the flowers will wither faster.

Did you know that the blooming period of cherry blossoms can actually be calculated?

The day when the sum of the highest temperatures of each day after February 1 exceeds 600 degrees Celsius, the cherry blossoms will bloom. This is the so-called "600-degree rule" for cherry blossoms. It takes about a week for cherry blossoms to bloom completely. On the fifth day of blooming, they are about 70% bloomed, which is the best time to see them. In practice, the predicted flowering period is very close to the actual flowering period.

○ ○ ○

The variety also affects the flowering period, which can be divided into early, mid and late cherry blossoms.

There are many varieties of cherry blossoms, the number can reach more than 300, and they can be classified in many ways. The most common way is to divide cherry blossoms into early cherry blossoms, mid cherry blossoms, late cherry blossoms and winter cherry blossoms according to their flowering period.

Early cherry blossoms, mid-season cherry blossoms, and late cherry blossoms all bloom in spring. After the early cherry blossoms, other varieties of cherry blossoms will also appear one after another, and the entire cherry blossom viewing season will last for a period of time. During this period, different varieties of cherry blossoms will bloom one after another, competing for beauty.

Early cherry blossoms: mid-to-late February to early March. The main varieties include Okanzakura, Bellflower Cherry, Winter Cherry, and Hatsubiren.

This type of cherry blossom begins to display its crimson flowers in early spring, when the weather is still cold in February every year. Among them, the bell-flower cherry blossom is named after its upside-down bell-shaped flowers, and the deep red flowers are like clusters of flames in the quiet early spring.

Mid-season cherry blossoms: bloom in mid-to-late March, with Somei Yoshino cherry being the most common. This is a deciduous tree with a height of about 5 to 12 meters. Its flowers bloom before the leaves. The flowers have five petals. The color of the flowers is light red when they first bloom, and gradually turns white when they are fully bloomed.

▲On March 20, Tokyo announced that the Somei Yoshino cherry trees had bloomed. (Photo source: Asahi Shimbun)

Late cherry blossoms: bloom in April, 10-15 days later than mid-season cherry blossoms. The main varieties are mountain cherry blossoms, pine moon cherry blossoms, and turmeric. Among them, turmeric is a rare yellow-green variety of cherry blossoms. The flowering period is mid-to-late April. It is a small tree.

In addition, there is a member of the cherry blossom family that does not follow the rules - October Sakura. This type of cherry blossom blooms twice a year, in late March or early April, and from October to December. October Sakura is a cultivated variety of the Higan Sakura series and has been widely planted since the 1800s. Watching cherry blossoms in autumn is really a special charm.

||||

(This article is compiled from CCTV News, China Daily, Knowledge is Power, Beijing News, Tadpole Music, etc.)

Produced by: Science Central Kitchen

Produced by: Beijing Science and Technology News | Beijing Science and Technology Media

Welcome to share to your circle of friends

Reproduction without authorization is prohibited