We began growing female Ginkgo trees at the Wood House Farm in 2007 for a USDA researcher when concern for genetic diversity became a concern. Ginkgo trees are the oldest known tree species on Earth and have no close relatives.
The project, "Fossil Atmospheres," is unique in both its scale and level of citizen science involvement.
(Rich Barclay)
Modern ginkgo leaves closely resemble fossilized specimens.
(Scott Wing) Citizen scientists can spot ginkgo leaves based on their distinctive fan-shaped appearance.
(Rich Barclay)
Urban planners love Ginkgo trees (Ginkgo biloba) almost as much as our (Gleditsia triacanthos), but they only like male Ginkgos. Nurseries guarantee male Ginkgos through cuttings, which is functionally cloning, and that quickly reduces genetic diversity.
Ginkgo has survived three mass extinctions, including the one that killed the dinosaurs. (Rich Barclay)
Smithsonian Scientists Are Using Ginkgo Leaves to Study Climate Change—They Need Your Help
Citizen scientists can submit leaf samples from their hometowns through the end of August
The next time you venture into the great outdoors, keep an eye out for Ginkgo bilobatrees,
which can be easily identified by their distinctive fan-shaped leaves.
If you find one—and you likely will, as the native Chinese plant is now
ubiquitious in the United States—take a moment to pluck a few leaves,
snap some photographs of the scene, and record your observations via the
iNaturalist mobile app. Then, package your sample in an envelope, drop it into the mailbox, and give yourself a pat on the back. Congratulations: You’ve just become a citizen scientist, helping researchers at the Smithsonian’s National Museum of Natural History use ginkgo leaves to study the past, present and future of climate change.
Perhaps best known for its pungent smell and medicinal properties, ginkgo actually boasts an impressive backstory. As the online portal for the museum’s Fossil Atmospheres
project explains, the conifer plant (meaning it has seeds but doesn’t
produce flowers) arrived on the scene more than 200 million years ago.
Surviving three mass extinctions, including the one that killed the
dinosaurs, ginkgo has retained a remarkably similar appearance
throughout its time on Earth. This characteristic makes it possible for
scientists to easily compare modern specimens with fossils dating to the
distant past—a practice that could help researchers assess how the
planet’s atmosphere has changed over time, as well as predict what
effect future climate shifts will have on Earth’s living creatures.
Grove of ginkgo trees being grown at carbon dioxide concentrations that range from 400 ppm to 1,000 ppm. (Rich Barclay)
Rich Barclay, the paleobotanist who leads Fossil Atmospheres, says the project consists of two main parts: an experiment based out of the Smithsonian Environmental Research Center in Edgewater, Maryland, and a multi-phase citizen science initiative. Per a Smithsonian Voices blog post penned by Barclay and Laura Soul,
the museum’s Deep Time Science Education Specialist, in June 2017, the
experimental side of the research revolves around a grove of
10-foot-tall ginkgo trees being grown at carbon dioxide concentrations
ranging from 400 parts per million (ppm), or the level found in the
atmosphere today, to 1,000 ppm, a ratio last seen when Earth’s climate
was so warm that there were no polar ice caps.
The citizen science component, on the other hand, began with crowdsourced stomatal counting—a plant’s stomatal index
reflects carbon dioxide concentration at the time of its growth,
enabling scientists to gauge the conditions in which a specimen
developed—and is set to continue with a newly launched leaf survey.
This latest phase, running for the entire month of August, asks science
enthusiasts from across the country to send in ginkgo leaves from their
local communities. These samples will be used to paint a clearer
picture of how a plant’s features reflect the environment in which it
grows, providing insights on contemporary climate that can then be
applied to prehistoric climates, as represented by well-preserved ginkgo
fossils.
Soul,
who leads the educational side of Fossil Atmospheres, explains, “We
can't go out and get leaves from every state in North America, but the
public can. . . and that's why citizen science performs [such] a vital
role in what we’re doing.”
She
adds, “[Citizen scientists] are enabling the project to have a much
broader scope and [helping researchers] answer questions that we
wouldn't be able to answer otherwise.”
To contribute, interested parties must follow a detailed set of instructionsoutlining the process
of obtaining, recording and submitting specimens. Be sure to follow
every step, from identifying the sex of a chosen ginkgo tree to noting
its exact location, uploading photos and observations to the iNaturalist app, and properly packaging the leaves, or else the scientists will not be able to use your sample. For more details, visit the project’s website or email NMNH-Fossil-Atmospheres@si.edu.
By restricting the time period in which samples are collected, as well as outlining specific instructions,
Barclay says the team will be able to reduce the number of variables
affecting stomatal count down to geographic range and environmental
factors such as temperature, rainfall, elevation and latitude.
Ultimately, data garnered from these public contributions will play a
key role in published scientific research. Even if specimens aren’t used
for Fossil Atmospheres specifically, Soul points out that they will be
permanently accessioned into the Smithsonian’s collections: She notes,
“Future scientists will be able to use them to answer questions that we
haven’t even thought of yet.”
The exact science behind the project
largely comes down to stomatal index, which serves as a climate proxy,
or means of reconstruction, for past carbon dioxide concentration. In
layman’s terms, stomata are tiny openings on leaves’ surfaces that let
in CO2 but expel oxygen and water. Stomatal index refers to the optimal
number of stomatal pores needed to facilitate this exchange and is
determined by an array of environmental factors, chief among them the
level of carbon dioxide in the atmosphere.
As
Barclay explains, low stomatal numbers tend to correspond with high
CO2, while high stomatal numbers correlate with low CO2. But while
researchers “know there’s a strong relationship between decreasing
number of pores. . . and increasing CO2,” previous studies have failed
to fully quantify this dynamic.
“We
knew we needed to redo [the research], and we wanted to do it in a more
realistic way,” the paleobotanist says. “We moved to this scenario
where we’re actually growing trees under elevated conditions, . . .
pushing the plants to higher CO2 concentrations than [have] ever been
studied.”
A plant’s stomatal index reflects carbon dioxide
concentration at the time of its growth, enabling scientists to gauge
the conditions in which a specimen developed.
(Rich Barclay)
According
to Barclay, Fossil Atmospheres is unique in both its scale and level of
citizen science involvement. In addition to the leaf survey, the
volunteer side of the project involves counting stomatal pores
captured in images of modern and fossilized leaves. This task is
decidedly more difficult than simply collecting and cataloguing leaves,
but the campaign’s Zooniverse page
offers tips, tutorials and practice rounds for those willing to give it
a try. (For what it’s worth, more than 3,300 participants have
contributed 31,000 classifications to date.) Samples collected via the
leaf survey will later be imaged and added to the counting page.
“Some
people are excellent at [counting], and some people struggle a bit
more,” Soul observes. Since each image is presented to multiple
volunteers, however, the team has found that maximizing participation
usually yields an accurate answer.
In
Barclay’s view, citizen science benefits everyone involved. Volunteers
have an opportunity to contribute valuable scientific research and learn
more about the topic at hand, while experts gain a trove of usable
data. With more individuals collecting leaves and counting stomatal
pores, the project can be completed in a reasonable amount of
time—namely, within the next several years.
Fossil
Atmospheres’ ultimate goal is to determine the relationship between
carbon dioxide and stomatal index. By doing so, Barclay and Soul write
in Smithsonian Voices, “We should be able to pick up a
fossil ginkgo leaf and know the composition of the air in which it
grew.” At the same time, the researchers hope to use their findings to
answer a key question about the future: “As we humans add carbon dioxide
to the atmosphere, how warm will the planet get?” The answer, according
to the pair, lies in the past, locked in the minute nooks and crannies
of ginkgo leaves’ surfaces.
“The
real benefit [for volunteers] is to participate in a project that's
actually answering useful questions about our changing climate, which is
one of the most pressing issues that we're facing at the moment,” Soul
concludes. “This kind of research. . . is going to be vital moving forward.”
The project, "Fossil Atmospheres," is unique in both its scale and level of citizen science involvement.
(Rich Barclay)
Modern ginkgo leaves closely resemble fossilized specimens.
(Scott Wing)
Citizen scientists can spot ginkgo leaves based on their distinctive fan-shaped appearance.
(Rich Barclay)
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