Early Bloomers
In 2010 and 2012, plants in the eastern U.S. produced flowers earlier than at any point in recorded history. In a new study which has the added interest of drawing on early data gathered by none other than U.S. environmental writers Henry David Thoreau and Aldo Leopold. Thoreau began observing bloom times in Massachusetts in 1852, and Leopold began in Wisconsin in 1935.
The scientists compared this historical data with modern, record-shattering high spring temperatures in Massachusetts and Wisconsin during 2010 and 2012.
They discovered that those two recent warm spells triggered many spring-flowering plants to blossom up to 4.1 days earlier for every 1 degree Celsius rise in average spring temperatures, which translates to 2.3 days for every 1 degree Fahrenheit.
Two of the best-known American environmental writers initiated extensive phenological observations of flowering times in the eastern United States that encompass 161 years of ecological change. From 1852–1858, Henry David Thoreau, author of Walden [20], observed flowering times in Concord, Massachusetts, USA. And from 1935–1945, Aldo Leopold, author of A Sand County Almanac [21], recorded flowering times in Dane County, Wisconsin, USA and near the site of his “Shack” in adjacent Sauk County [4]. Several recent re-surveys at these locations [22]–[25], nearly 1500km apart, indicate that many spring-flowering plants now flower much earlier than in the past. This trend appears to be attributable to especially warmer spring (March, April, May) temperatures [25]–[27]. In 2010 and 2012 in Massachusetts [5], and 2012 in Wisconsin [4], spring temperatures were the warmest on record. These long-term datasets thus provide a rare opportunity to investigate if historical relationships between flowering times and spring temperatures apply during these record-breaking years. These observational data are especially timely because recent meta-analyses of flowering phenology [28] have documented that controlled warming experiments greatly under-predict flowering phenology when compared with their responses in natural settings. Thus, historical phenological data, such as those initiated by Thoreau and Leopold, are critical to understanding plant responses to current and future warming, and to test whether increasing temperatures may result in continued earlier flowering.
The major interest is if plants can transition to budding earlier and earlier. The challenge to plants is if they can adapt fast enough as climate changes radically or is there some physical limit against which you're going to bump up [so] that you can't adapt any longer?
Another worry is that plants will flower early and a late winter freeze will destroy the buds. That will likely weaken the plant, though not kill it outright.
Early blooming has tremendous implications for the environment as a whole.
Henry David Thoreau on Spring:
"is a natural resurrection, an experience of immortality."