Henry David Thoreau may be best known as a philosopher, writer, and Transcendentalist, but the Thoreau Society’s Annual Gathering, which begins Thursday in Concord, exactly 195 years after his birth, will focus on his role as ecologist.
Through hikes, a presentation on Thoreau’s contributions to climate-change science, and a keynote speech from Pulitzer Prize winner Edward O. Wilson, participants from all over the world will explore Thoreau’s writings about the relationship between people and their environment.
Wilson, who lives in Lexington, is a Pellegrino University research professor emeritus and honorary curator in entomology at the Museum of Comparative Zoology at Harvard University. He is known as a scientist, conservationist, and author who has advocated for the preservation of biodiversity.
But Wilson is also a selfdescribed Thoreauvian. He said in a phone interview Monday that the 19th-century writer had helped him and many others understand ecology.
“In order to get public support of conservation, it was not sufficient to just publish scientific reports, you had to enter the world of literature and reach people directly through their hearts and not just their minds,” he said.
In his keynote presentation, Wilson said, he will read from his book “The Future of Life,” which starts with “A Letter to Thoreau.”
This year marks the 150th anniversary of the legendary Concord native’s death, so the theme of the Annual Gathering is “Celebrating 150 Years of Thoreau’s Life, Works, and Legacy.”
In his most famous work, “Walden,” Thoreau reflects on his time alone in a cabin in the woods near the Concord pond, and meanders through topics like political freedom and spirituality, while immersed in and closely observing nature.
“This year we’re really highlighting Thoreau as ecologist,” said Michael Frederick, executive director at the Thoreau Society. “He practiced ecology before there was a word for it.”
The schedule for the four-day conference includes tours, panel discussions, and presentations by noteworthy scholars; the list includes Richard Primack, professor of biology at Boston University.
About nine years ago, Primack started poring through data that Thoreau scholars were well aware of but that had somehow escaped the notice of scientists. Thoreau, it turned out, had compiled the oldest complete set of biological events in the country, via his detailed observations of when birds arrived and plants flowered in Concord, said Primack.
Primack used the data to find a local “fingerprint” of climate change.
“What we find is that the plants in Massachusetts are flowering dramatically earlier than Thoreau’s times but that the birds are changing a little bit — a detectable amount but not as much as the plants,” he said. “At the meeting on Thursday, I’ll tell people all these results we’ve found and emphasize that Thoreau could be called the climate change scientist.”
Warmer temperatures found in Concord are only partially attributable to global warming, said Primack. (The so-called “urban heat island effect,” from the development of the Boston area, plays a large role too.)
Primack studies the species decline that comes with higher temperatures. Concord, for example, historically had 21 species of orchids growing but now only seven can be found, he said.
“At least some of the loss is because of warming temperatures,” he said.
Also thanks to Thoreau, we can understand just how freakishly warm this winter was. In its wake, many plants flowered earlier than ever before, breaking records, said Primack.
For example, high bush blueberries flowered in mid-May in Thoreau’s time, he said. In recent years, early May or late April was the norm. This year, said Primack, the starting date was an astonishing April 1.
Also on the gathering’s program is Wen Stephenson, a writer living in Wayland and a former Boston Globe editor, who will present “Walking Home from Walden,” also the title of an essay he wrote.
“The essay, and my talk, is about how Thoreau helped me wake up to the climate crisis, and how I find him a source for a different kind of engagement, which is both political and spiritual,” said Stephenson.
It’s important to not simply talk about climate change, he said, but to take action to mitigate it.
“We can’t just be satisfied with reconnecting with nature anymore, whatever that means now,” Stephenson said. “It’s far more serious than that, unfortunately. And if we’re going to preserve a livable planet, it’s going to take a lot of political engagement to make that happen.”
For more information on the Annual Gathering, go to www.thoreausociety.org. Some events are free, but space is limited. Most of the programs require registration.