Drawing on records dating back to the journals of Henry David Thoreau, scientists at Harvard University have found that different plant families near Walden Pond have borne the effects of climate change in strikingly different ways. Some of the plant families hit hardest by global warming have included beloved species like lilies, orchids, violets, roses, and dogwoods.
The work appears this week in the Proceedings of the National Academy of Sciences.
Over the past 150 years, some of the plants in Thoreau's woods have shifted their flowering time by as much as three weeks as spring temperatures have risen, the researchers say, while others have been less flexible. Many plant families that have proven unable to adjust their flowering time have experienced sharp declines or even elimination from the local landscape -- the fate of nearly two-thirds of the plants Thoreau found in the 1850s around Walden Pond in Concord, Mass.
"It had been thought that climate change would result in uniform shifts across plant species, but our work shows that plant species do not respond to climate change uniformly or randomly," says Charles C. Davis, assistant professor of organismic and evolutionary biology in Harvard's Faculty of Arts and Sciences. "Some plants around Walden Pond have been quite resilient in the face of climate change, while others have fared far worse. Closely related species that are not able to adjust their flowering times in the face of rising temperatures are decreasing in abundance."
Some 27 percent of all species Thoreau recorded in the mid-19th century are now locally extinct, and another 36 percent are so sparse that extinction may be imminent. Plant families that have been especially hard-hit by global warming have included lilies, orchids, buttercups, violets, roses, dogwoods, and mints. Many of the gainers have been weedier mustards and knotweeds, along with various non-native species.
"The species harmed by climate change are among the most charismatic found in the New England landscape," Davis says. Scientists can be reasonably confident these losses have resulted from climate change and not habitat loss, he adds, since 60 percent of the land in Concord has remained protected or undeveloped since Thoreau's observations of the area between 1851 and 1858.
Understanding the decline of species abundance over time is constrained by the limited availability of historic data. Davis' work with Harvard graduate students Charles Willis and Brad Ruhfel combines contemporary data, collected by scientists Richard Primack and Abraham Miller-Rushing at Boston University, with Thoreau's records from his time spent at Walden Pond. Thoreau kept meticulous notes documenting the natural history of the region, plant species occurrences, and flowering times. Since then, botanists have resurveyed the territory to create a unique, community-level perspective covering 150 years. During this period, the mean annual temperature in the Concord area has increased by 2.4 degrees Celsius, or 4.3 degrees Fahrenheit.
"The plants in our survey now flower, on average, one week earlier in the spring than their ancestors did in Thoreau's time," Davis says. "However, there is wide variation among plant families. Some have shown no shift in flowering at all, while others now bloom 16 to 20 days earlier in the spring."
As mean annual temperatures increase, plants can adjust their growth patterns in several ways. For example, forests shift toward the poles, alpine tree lines move up mountains to higher altitudes, and flowering time can shift. During eras of climate change, plants that cannot adjust their flowering schedule -- and thus flower at sub-optimal times -- may experience dramatic declines in population size and local extinction.
Steve Bradt | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences