Walden Pond isn’t just the site of Henry David Thoreau’s two-year stint in which he documented a more simple, natural life, it is now the subject of a climate change study that shows how leaf-out times of trees and shrubs have changed since the 1850s.
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As a result of Thoreau’s observations, researchers at Boston University have revealed that the leaf-out times of trees and shrubs at Walden Pond are an average of 18 days earlier than observed by Thoreau in the mid 1800s.
“By comparing historical observations with current experiments, we see that climate change is creating a whole new risk for the native plants in Concord,” said Boston University Professor Richard Primack. “Weather in New England is unpredictable, and if plants leaf out early in warm years, they risk having their leaves damaged by a surprise frost. But if plants wait to leaf out until after all chance of frost is lost, they may lose their competitive advantage.”
However, not all plants respond in the same way, the result of which is that native species eventually may be threatened and lose competitive advantage to more resilient invasive shrubs such as Japanese barberry, according to a study published in the new edition of New Phytologist.
“We started to wonder if all trees and shrubs in Concord are equally responsive to warming temperatures in the spring,” says Caroline Polgar, a graduate student with Primack. What she found was surprising. “All species — no exceptions — are leafing out earlier now than they did in Thoreau’s time,” she said. “On average, woody plants in Concord leaf out 18 days earlier now.”
“Our current observations show that plants in Concord today are leafing out earlier than in Thoreau’s time in response to warm temperatures,” she said. “However, the experiments show that as spring weather continues to warm, it will be the invasive shrubs that will be best able to take advantage of the changing conditions.”
Read more at Boston University.
Walden Pond image via Wikipedia.
