Old plant collections reveal that nature is changing at lightning speed
Plants all over the world are on the move. Over the past few decades, they have shifted their habitats by about 5.6 kilometres per year, according to a new study.
Researchers have examined the world's herbaria in a new study. Siri Birkeland at the Natural History Museum has participated.(Photo: Bård Amundsen)
Plants have been collected, pressed, dried, and mounted on flat sheets since the 1600s. The oldest specimens at the Natural History Museum in Norway's capital date back to the 1700s.
The sheet that evolutionary biologist Siri Birkeland carefully opens and shows is from 1878.
It belongs to the Arctic herbarium, one of the most important sources for understanding how northern ecosystems have changed over time.
The plant itself is not particularly spectacular. It's a very common species that grows in Norwegian mountains, namely mountain sorrel. Or Oxyria digyna, as she prefers to call it.
But this specimen carries a unique story and may now help researchers better understand what could happen in the future.
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Evolutionary biologist Siri Birkeland can see changes over time. "With herbarium data, we can go back in history and see how plants have changed, both in appearance and genetically. It gives us a unique opportunity to study how species adapt to environmental changes," she says.(Photo: Siw Ellen Jakobsen)
A large expedition
The plant was collected on Bear Island during the great North Sea expeditions at the end of the 1800s.
This was one of the first major scientific marine research expeditions to investigate the waters between Iceland, Jan Mayen, and Svalbard.
While the researchers on the ship studied the seas, the physician and naturalist Daniel Danielssen went ashore to collect plants.
Between 1876 and 1878, the ship Vøringen was used as a research vessel for the Norwegian North Sea Expedition. A naturalist onboard collected plant specimens for museums.(Image: Wikimedia)
The plants that Danielssen found were pressed, dried, and sent to museums, where they have remained ever since.
Over time, additional samples of the same species have been gathered.
"The same species are collected again and again, often from the same areas. This creates a historical record showing which species grow where at different times," says Birkeland.
She has contributed to a large international research project that uses these herbarium collections to find out how plant communities have changed over the past 30 years.
Can extract new information
The study is based on millions of dried plants from herbaria around the world. The information is compiled in the global database Global Biodiversity Information Facility (GBIF).
Major changes in biodiversity may occur in the future. In the vascular plant herbarium at the Natural History Museum there are over 1.1 million specimens. They can help researchers document whether a species is in serious decline.(Photo: Aksel Kjær Vidnes)
Until quite recently, these specimens were largely overlooked in museum archives, both at the Natural History Museum in Oslo and in the roughly 3,000 herbaria that exist around the world.
Now they have gained renewed importance.
Due to digitisation and other modern technologies, such as artificial intelligence and DNA analyses, researchers can extract large amounts of information from the old plants.
The information may be crucial for understanding how nature responds to a warming climate.
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And mountain sorrel has gained a completely new role in research.
"The entire genome of the species has recently been mapped by a researcher in our research group. This opens up entirely new possibilities for linking historical herbarium data with genetic analyses," says Birkeland.
Plants in the north are moving the fastest
Each plant represents a data point, explains Birkeland.
"The sheet shows where and when the plant was collected, who found it, and what species it is," she says.
When this is compiled into huge databases, researchers can see how species' distributions have changed over time.
What they find in the new study, which is currently published in a so-called preprint, suggests that the changes are dramatic. A preprint is an early version of a research article that has not yet been peer-reviewed or published in a scientific journal.
The study shows that plant species all over the world are moving at a rapid pace, with a median shift of 5.6 kilometres per year.
According to the calculations, plants in northern areas will move the fastest, says Birkeland.
"One of the main findings is that plants in the north move faster than plants in the tropics when the climate changes. This is especially true for plants in tropical areas with high topographic variation," she says. "This means that many species may not be able to move fast enough to keep up with climate change."
This could mean that more plant species in the north could face extinction.
Species are pushed northwards and upwards
Temperatures in the Arctic are rising about four times faster than the global average, Birkeland notes.
"As the climate changes, species are pushed northwards or upwards into the mountains," she says.
For species already living in the far north, there may be nowhere left to go. This is especially true for alpine plants like mountain sorrel.
"Will plants eventually run out of places to move to?"
"So far, there is limited evidence that plant species have already gone extinct in the Arctic due to climate change. But the vegetation is already changing. For example, we see much more shrub growth in Arctic areas," says Birkeland.
The use of artificial intelligence
In the past, researchers lacked the tools to analyse such large amounts of data.
Birkeland says that the biggest difference is that these data have now been digitised and made publicly accessible through large databases like GBIF.
"In addition, artificial intelligence makes it possible to analyse large amounts of herbarium data in new and exciting ways. For example, automated image analysis can reveal how plant traits have changed over time," she says.
A large number of species will be lost, says Inger Greve Alvos.(Photo: UiT)
One of the most pressing questions
Inger Greve Alvos is a biology professor at UiT The Arctic University of Norway.
She believes that Birkeland and her colleagues make excellent use of the enormous potential that lies in the world's herbaria.
"They have gone through an impressive amount of data to find answers to one of the most pressing questions we have, namely what we can expect to happen to plants worldwide as a result of ongoing climate change," she says.
As expected, the results show that plants in our latitudes are expected to migrate northwards and upwards, she says.
"But the study also shows that the response is complex and that we can expect a large number of species to be lost," she says.
