Record-Breaking Weather At Walden Pond Testing Limits Of Spring-Blooming Plants

1/17/2013  With record-breaking warm spring weather in 2010 and 2012 resulting in the earliest known flowering times in 161 years of recorded history in two U.S. locations, according to a new Boston University-initiated study published today.

Walden Pond, Boston, MA, June 11, 2011.  Photo by erikorama/Flickr

Walden Pond, Boston, MA, June 11, 2011. Photo by erikorama/Flickr

Scientists now are pondering if at some point plants will be unable to successfully keep adapting to a changing climate.

Records kept since 1852 by Henry David Thoreau near Walden Pond in Massachusetts and since 1935 by Aldo Leopold at his Sand County shack in Wisconsin, show that common wildflowers now blossom 20 days earlier and 24 days earlier respectively than in the past. Many plants need a long winter to undergo the physiological changes needed to bloom in the spring. While the researchers said there is no sign plants have hit the limit of their ability to respond to record-breaking warm temperatures, the consequences of earlier flowering for plant productivity, pollinators like bees, and ecosystems in general remain unknown and could be harmful.

“In 2010, plants flowered three weeks earlier than in Thoreau’s time and we thought we’d never see another year like that,” said Boston University biology Prof. Richard Primack, who co-authored the paper, along with BU postdoctoral researcher Elizabeth Ellwood and colleagues Charles Davis at Harvard University and Stanley Temple at the University of Wisconsin. “But then two years later we had another record early flowering year both in Massachusetts and in Wisconsin.”

This new study showed that many plants – such as highbush blueberry and the pink lady’s slipper orchid – flowered up to 4.1 days earlier for every degree Celsius rise in mean spring temperatures (2.3 days earlier for every degree F rise in spring temperatures). Significantly, it showed that the historical patterns of early flowering in warm years and later in cold years can predict flowering times even in exceptionally warm years. It also found that the wildflowers just keep flowering earlier as the weather warms.

“While these plants have shown remarkable resilience over decades of changing weather, it is unknown whether plant flowering times will continue on a linear trajectory of earlier flowering, or if at some point plants instead will be unable to keep pace with climate change and just start dying,” said Primack. “Thoreau and Leopold are icons of the American environmental movement and it is astonishing that the records both kept decades ago can be used today to demonstrate the impacts of climate change on plant flowering times.”

Newswise