Washington Cherry Blossom Festival

 By Richard B. Primack

 

“To him who contemplates a trait of natural beauty no harm or disappointment can come.” Henry David Thoreau in Excursions.

 

The cherry blossom festival in Washington, DC is a celebration of the beauty of nature. But planning for the festival is challenging because the timing of the peak display of cherry flowers on the National Mall depends on the weather. This year was the second earliest flowering date for the cherry trees in the last 100 years. 

 

Photo 1: Cherry trees flowering in Washington, DC. (photo source: Washington Post)

It is impossible to predict in advance when the cherry trees will bloom each spring, because warm weather speeds up flowering and cool weather delays flowering. But over the last 50 years, the cherry trees in Washington have bloomed about 2 weeks earlier than in the past due to a warming climate. And the prediction is that this earlier flowering trend will continue over the coming half century as the climate continues to warm. 

Figure 1: Cherry trees have been flowering ever earlier over the past 50 years. (figure source: Washington Post)

 

This shift has happened because cherry trees respond primarily to spring temperatures, and springs have been getting warmer due to ever increasing levels of atmospheric carbon dioxide and other greenhouse gases. Aside from temperature, other factors, such as precipitation, humidity and sunlight, have relatively little effect on the flowering times. 

In addition to earlier flowering times, it is also possible that these rising temperatures could harm trees directly through heat and drought, or indirectly through increases in insect pests and disease. The results might be a diminished floral display in future years. 

For more details, see full article: LINK   

Glass Flowers Field Trip

 By Richard B. Primack 

 

“We discover a new world every time that we see the earth again after it has been covered for a season with snow.” Henry David Thoreau in his Journal.

 

 

Last fall, the Plant Biology class took a field trip to the Glass Flowers exhibit at the Museum of Natural History at Harvard University. It’s a great place to study the characteristics of plants during the winter, and to learn to recognize economically important plants and the features of plant families. 

 

Photo 1: The Plant Biology class at the exhibit.

 

Photo 2: A tea plant made of colored glass.

 

Photo 3: Students carrying out a class activity. Note that one student is using pencil and paper, while the other student is taking notes with a smartphone. 

 

Photo 4: Students working together as a team, again using electronic devices. 

 

 

Bare Pond in the Webster Woods

By Richard B. Primack

 

“[Walden] pond never breaks up so soon as the others in the neighborhood, on account both of its greater depth and its having no stream passing through it to melt or wear away the ice. It indicates better than any water hereabouts the absolute progress of the season, being least affected by transient changes in temperature.” Henry David Thoreau in Walden.

 

Bare Pond is a hidden gem in the Webster Woods. 

Due to its small size and shallow depth, Bare Pond is constantly changing from day to day and bringing new surprises with each season. 

Photo 1: Bare Pond in autumn, with unusually high water levels for this time of year. 

 

Bare Pond’s rapid changes are in contrast with larger and deeper bodies of water, such as Walden Pond in Concord. 

Video 1: On a winter afternoon as the sun is setting, springtails jumping on the pond surface create a delightful sparkling display.  

In a typical year, the pond fills with water in the autumn and winter and dries out by the following summer, making it “bare” (and explaining the reason for its name). Because of this cycle, the pond does not have any fish, making it ideal for breeding amphibians and their larval stages. 

The pond is a breeding site for the rare yellow-spotted salamander. “Save the salamanders” became the rallying cry of citizen efforts to protect this section of the Webster Woods. Wood frogs and spring peepers also breed in the pond.

Video 2: On Sunday, March 10 of this year, hundreds of wood frogs floated on the surface of the pond, creating a distinctive quacking chorus.  

Warning to Cherry Blossom Travelers

 By Richard B. Primack

 

“We are acquainted with a mere pellicle of the globe on which we live…  We know not where we are. Beside, we are sound asleep nearly half our time.” Henry David Thoreau in Walden.

 

Visiting Japan for the cherry blossom festival is a life-long goal for many international travelers, due to its wonderous beauty and associated cultural activities. But the brief festival’s date shifts earlier or later depending on the weather. 

 

Photo 1: For a brief period sometime in late March or early April, people in Japan enjoy the cherry blossom festival, as shown in this photo from Tokyo.

 

Spring warming is the most important determinant of flowering times for cherry trees. And because spring weather is getting warmer due to global climate change, cherry trees are flowering ever earlier, making it harder to predict in advance when the festival will be. A traveler could arrive in Tokyo for the festival and discover that the festival had happened a week earlier.

 

Photo 2: In Kyoto, flowering cherries add to the beauty of the temples.

Cherry flowering times have been recorded across Japan for over a thousand years, making them among the best-documented examples of the biological effects of climate change in the world. Yoshino cherries, which are the most common variety of cherry trees planted in cities, are now flowering about two weeks earlier than they did 50 to 60 years ago, due to the warmer weather associated with climate change.

 

People hoping to see the cherry blossom festival in Tokyo or Kyoto need be flexible in their travel plans. Or they can always travel further north in Japan to catch a festival in a cooler city, or even catch the festival in neighboring South Korea.

 

Photo 3: The cherry blossom festival is also celebrated in South Korea. 

 

For a longer version of this article published by BBC, see: LINK