Tuesday, March 26, 2024

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   


Tuesday, March 19, 2024

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. 



 

 


Wednesday, March 13, 2024

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.  


Tuesday, March 5, 2024

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



Wednesday, February 28, 2024

The Charles River Greenway at 30

By Richard B. Primack 

“Not only the channel but one or both banks of every river should be a public highway.” Henry David Thoreau in his Journal.

The Upper Charles River Reservation, one of Newton’s open space gems, is home to the Charles River Greenway, running for miles along both sides of the river from Watertown through Newton and Waltham to Commonwealth Avenue. The Greenway, opened to the public around 1992, is now around 30 years old!


Photo 1: A view of the river from a Greenway bridge. 


Prior to the Greenway’s construction, public access to the river in this area was blocked. Even though the riverbank and margin belonged to the state, local residences and businesses had extended their activities all the way down to the river, often erecting fences and building parking lots.


Photo 2: Many bridges cross the river along the Greenway.

 

Starting in 1991, the Massachusetts Department of Conservation and Recreation (DCR) began reasserting control over the river margin with two goals in mind. First, to restore the natural environment as habitat for native plant and animal life. Second, to provide public access to the river and its ecosystems along connected paths. 


Photo 3: Wide, well-maintained paths run along the Greenway.


By any reasonable measure, the Greenway has achieved its goals. Along the river, the DCR was successful at building paths, restoring forests, and protecting wetlands. The Greenway is now heavily used by the public, and it is hard to imagine life in this area without this beautiful and accessible river park.


This is a shortened version of an article published in the Newton Conservators Newsletter: LINK





Wednesday, February 21, 2024

Dormant Twigs in Multiple Temperatures

 By Richard B. Primack

 

Many times I have thought that if the particular tree, commonly an elm, under which I was walking or riding were the only one like it in the country, it would be worth a journey across the continent to see it.” Henry David Thoreau in his Journal.

 

Dormant twig studies have emerged as one of the most effective ways to study the effects of a warming climate on the leafing out and flower times of woody plants. 

On February 5, Selby Vaughn defended an undergraduate honors thesis which used dormant twigs to investigate the effects of a wide range of temperatures on the flowering and leafing times of 12 species of trees and shrubs. 


Photo 1: Selby and committee members Richard Primack, Max Helmberger, and Cheryl Knott.


The thesis was titled: PHENOLOGICAL TRENDS IN THE EFFECTS OF TEMPERATURE ON FLOWERING AND LEAFING OUT TIMES OF WOODY PLANTS USING A DORMANT TWIG EXPERIMENT.


Photo 2: Twigs of 12 species being evaluated for stages of flowering and leafing out.

 

As predicted, the tree and shrub species flowered and leafed out earlier in warmer temperature conditions. The study was noteworthy in its use of a wider variety of temperatures than any previous dormant twig study, which will help to determine if species responses to temperature are linear rather than curvilinear. 



Tuesday, February 13, 2024

Winter Gardening in Boston

 By Richard B. Primack

 

The winter, with its snow and ice, is not an evil to be corrected. It is as it was designed and made to be, for the artist has had leisure to add beauty to use.” Henry David Thoreau in his Journal.

 

People associate New England with harsh cold winters; a time for gardeners to stay indoors for five months. But the climate has now become milder, with this year’s average temperature fully four degrees above normal. 

As a result, yesterday, in mid-February, our garden was free of snow and with an abundance of spring-like growth.


Photo 1: Mid-February garden scene.

 

I noticed the following strange sights for wintertime: 

Photo 2: Bok choy, a cold-tolerant vegetable, looked good enough to eat. 

 

Photo 3: Lettuce and parsley have been doing surprisingly well in a protected spot of the garden. 

 

Photo 4: Our strawberry plants have started to produce new leaves and will be ready when the warm spring weather arrives. 

 

Photo 5: But then today, the weather suddenly shifted, bringing a winter storm that covered everything in snow. 

Hopefully the plants will survive until the snow melts. It's becoming a new world for gardeners and their plants.