Biologists at Boston University report that trees and shrubs at Walden Pond are leafing out an average of 18 days earlier than the mid-1800s, when Henry David Thoreau made his studies there of nature.
The scientists looked at Thoreau's observations on leaf-out times in Concord, MA and they did the same over the past five springs. Boston University Professor Richard Primack said that "climate change is creating a whole new risk for the native plants in Concord." He explained that if plants leaf out early in years that are comparatively warm, they could be damaged by frost, but if they leaf out after frost is gone, then they may lose their competitive advantage to invasives that are more resilient.
The scientists believe that if spring temperatures continue to rise, invasive plants will be the ones that take advantage of the warmer climate. Studies are also going forward on flowering dates, the flight times of butterflies, and the arrivals of migratory birds.