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.


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.

Monday, February 5, 2024

How Woody Plants Manage the Shifts from Fall to Winter to Spring

 By Richard B. Primack


“I frequently tramped eight or ten miles through the deepest snow to keep an appointment with a beech-tree, or a yellow birch, or an old acquaintance among the pines.” Henry David Thoreau inWalden, p. 288.



In a recent article in the Old Farmer’s Almanac Garden Guide, I describe how trees survive the extreme cold weather of the northern climate.  

In autumn, woody plants start preparing for winter. When their leaves change color and drop, their twigs, branches and trunks start to lose water. As a result, their cells contain higher concentrations of sugars, salts, and organic compounds. 

Photo 1: In autumn, woody plants lose their leaves and prepare for winter.

This change lowers the freezing point of the cells and tissues and allows them to survive temperatures far below the normal freezing point of water. 

Photo 2: Trees have the ability to survive months of cold and snowy weather.


In the late winter and early spring, trees and shrubs have three ways to know when it is time to re-hydrate their tissues and start growing again. 

First, plants can stay dormant until they have experienced a certain number of cold winter days. They count these cold winter days to avoid being fooled into leafing out on abnormally warm days in January and February. 

Second, plants sense spring warmth. After they experience a certain number of warm days each spring, their buds start to swell and then they leaf out and flower. 

Third, plants also sense daylength or photoperiod. As days get longer in the spring, trees get itchy to leaf out and are quick to grow in response to warmer weather. 

Warming temperatures driven by climate change is making it harder for many species to detect how to avoid or handle winter cold and spring frosts. Warmer temperatures can fool trees such as apples and pears into leafing out and flowering several weeks earlier than normal, increasing their vulnerability to late frosts and damaging fruit production. Gardeners and farmers need to be aware of these climate change risks when deciding what trees and shrubs to plant. 

Photo 3: Unpredictable late frosts sometimes damage flowers and young leaves.

In coming decades, many cold-loving evergreen tree species (such as spruces and firs) in the northern United States and Canada will become less abundant when climate change challenges become too much for them to bear, and they will be replaced by deciduous species, such as maples and beeches. In turn, forests currently dominated by maple and beech trees will be gradually occupied by native species from farther south, such as oaks and hickories. 


Photo 4: Future northern gardens might include plants originally from warmer climates, such as figs and crepe myrtles. 

Here is a link to the article: LINK 


Tuesday, January 30, 2024

Corey and the Raven

 By Richard B. Primack with help from ChatGPT

Over the past few months, my colleagues and I have consulted with Corey Callaghan (University of Florida) on statistical techniques for combining eBird citizen science data with historical data from Thoreau and others to detect the effects of climate change on the timing of migratory bird spring arrival in Concord. The following is a poem about our decision to invite Corey to join our group. The first draft was written by ChatGPT and then revised by me. 


In confused thought, 'neath COVID's hazy cloud,

I climbed Seminary Hill, where gloom enshrouds,

A dusk of gathering tempest, rain's threat unfurls,

Mind entwined with mysteries, Thoreau's dark twirls.


A spring bird enigma, warblers concealed in shade,

Migratory notes sought, a riddle displayed,

Observers like Brewster, Griscom and more,

Birds seen centuries past, records to explore.


Photo 1: Henry David Thoreau recorded bird arrival times in the 1850s. Source – National Portrait Gallery, Smithsonian Institution

Rosey Corey, from recent decades now gone,

And now eBird's chorus, a modern song,

Could all combine, both present and yore,

Showing how time changed Concord birds’ travel chore?


Photo 2: eBird observers are making modern observations. 


In shadows I pondered, the statistical abyss,

Seeking insight, a guide in the mist,

Perhaps Corey Callaghan, with methods so bold,

Using subsampling lists, climate’s keys could unfold.


Photo 3: Corey Callaghan from the University of Florida.


Or another modeler, with stochastic grace,

Climate change effects, might better embrace?

Questions arose, trust hung in the air,

Seeking a savant, to unravel the snare.


As church spire neared, atop that steep knoll,

A sight gripped my soul, a tale to extol,

A raven, solitary, on steeple it swayed,

Wind's fierce caress, in dance it displayed.


Photo 4: A raven provides the answer. 

Midst tempest's lull, a mournful refrain,

Answering my quandary, a voice to explain,

"Caw!" it crooned, a spectral reply,

"Corey!" it whispered, the enigma unveiled nigh.

“Corey!” again, secrets since Thoreau’s Concord of yore,

Unlock and reveal evermore.

Monday, January 22, 2024

Echoes of Walden: A Climate Chronicle Version

 By Richard B. Primack with help from Chat AI and Willow E. Primack

[This poem was written largely by Chat AI based on a short essay by Richard and using prompts from Willow. Richard spent some time polishing the poem.]


In the warming world's embrace,
Unfolding petals rush to face
A sun too eager in its climb.
Wildflowers in Concord's heart,
Bloom early—nature's art
Distorted by a clock unseen.

Photo 1: Pink lady’s slipper orchid (source -

Red maples, white oaks stretch

New leaves to skies, a net to catch
Time lost, fourteen days erased.
The forest floor, once bathed in spring light,
Now shaded, in the relentless night
From canopies formed too soon.

Photo 2: Red Maples (source --

The birds, unswayed, keep their course,

Arriving as if by some ancient force,
Unaware of the disrupted tune.
Insects, on the other hand,
Dance to a warmer land's command,
A symphony of disarray.

Photo 3: American Redstart (source - © Evan Lipton eBird S29730553).

Halfway through this tale of change,

I ponder on the range
Of Thoreau’s words, a guide, a boon.
How much of what we see is real?
Is there more we can reveal
In this ceaseless quest, our plight?

To be awake is to be alive,
But in this truth, do we contrive
To see the world in Thoreau's light?
Can we follow his simple lead,
In word, in thought, in deed,
As the planet warms, as species flee?

Live simply, so others simply live,
To nature’s call, attention give,
Reduce, reuse, our creed.
Let's tread softly where we roam,
For this Earth, our only home,
Needs guardians of its fragile dream.


In the echoes of Walden's shore,
We find a task worth fighting for:
To restore the rhythm of the natural theme.

Tuesday, January 16, 2024

A Few Common Tree Species Make Up Half of Tropical Rainforests

 By Richard B. Primack

“This winter they are cutting down our woods more seriously than ever….Thank God they cannot cut down the clouds!” Henry David Thoreau in his Journal.

A recently published study of over one million trees from 1,568 locations found that just 2% of tree species make up 50% of the total number of trees in tropical forests across Africa, the Amazon, and Southeast Asia. Each continent’s forests consist of the same proportions of a few common species and many rare species. 

Figure 1: Dots show the locations of forest plots used in the study. 

The study scientists estimate that just 1,053 species account for half of the planet’s 800 billion tropical forest trees. The other half are comprised of 46,000 tree species, many of which are rare. 

Photo 1: Measuring trees at Bako National Park, Malaysia.


These findings suggest that by focusing attention on these relatively few common tree species, we can probably predict how the whole forest will respond to global climate change. This is especially important because tropical forests contain a tremendous amount of stored carbon, and are a globally important carbon sink.

Photo 2: Lainie Qie records data in the field.


The study is also significant because it involved hundreds of scientists cooperating to assemble a gigantic international data base.

Here is the citation to the paper and a LINK:

Declan Cooper, Simon Lewis ... RB Primack, et. al, 2024. Consistent patterns of common species across tropical tree communities. Nature