The trends are outlined in a new study by scientists at Boston and Harvard Universities and the University of Wisconsin-Madison. The study was published January 16th in the Public Library of Science One (PLoS One).
The researchers compared blooming times recorded by Henry David Thoreau from 1852- 1858 near Walden Pond and similar studies from 1935-1945 recorded by Aldo Leopold at his Sand County shack near Baraboo, WI.
Boston University Professor Richard Primack said that flowering times in 2012 were the earliest ever recorded in Massachusetts and Wisconsin. Many plants, including highbush blueberry and the pink lady's slipper orchid are flowering 4.1 days earler for every degree Celsius rise in mean spring temperatures. Primack said that it's not known whether plants will continue on a trajectory of flowering early, or if "at some point plants instead will be unable to keep pace with climate change and just start dying."
In Wisconsin, Stan Temple, an emeritus UW-Madison professor of wildlife ecology, noted that the Door County WI cherry crop last year was destroyed because the trees bloomed early in response to record-breaking warm temperatures and were later hit by a ruinous frost.
Thoreau kept blooming records on 32 native plant species, and Leopold recorded data for 23 species in southern Wisconsin.