The plants and flowers that Henry David Thoreau lovingly inventoried around Walden Pond 156 years ago are disappearing due to climate change. Researchers from Harvard and Boston Universities have tracked how warming temperatures have shifted the flowering times of 473 plant species in the woods at Walden Pond and elsewhere in Concord. Orchids, dogwoods, lilies, and many sunflower relatives are declining more swiftly than other species.
Climate-induced loss of plant diversity in Concord is alarming—especially since 60% of the area has been protected or underdeveloped since Thoreau’s time. But rapid temperature changes have led to changes in the timing of seasonal activities. Since Thoreau’s time, species now flower an average of seven days earlier—bad news for those dependent on pollinators, like bees, who have not responded in kind, or who are suffering population declines as well. The species in decline include anemones, buttercups, asters, campanulas, bluets, bladderworts, dogwoods, lilies, mints, orchids, roses, saxifrages, and violets.
Sounds like a poem, doesn’t it? A poem falling silent. . . The mean temperature in the Concord area has risen 2.4 degrees Celsius over the past 100 years and is expected to climb between 1.1 and 6.4 degrees Celsius during the next 100 years. The paper is appearing in the Proceedings of the National Academies of Sciences.