Unlike animals, how do plants migrate if they are rooted in one place and don’t have the ability to escape when things get worse? This can pose major challenges when a changing climate makes certain areas less suitable.
However, while individual plants cannot migrate, plant species can. They do this by scattering their seeds in the hope that some of them will land on hospitable soil. And because plants migrate in this way over time, entire ecosystems may need to migrate with them in a process that scientists are studying.
“Plants are changing their geographic ranges, and it’s happening whether we realize it or not.“, observes Jenny McGuire, assistant professor in the Schools of Biological Sciences and Earth and Atmospheric Sciences at Georgia Tech, in the United States, co-author of a to study in investigating how and why plants moved through geographic time in North America and where they are going.
“As seeds are dropped or transported to distant locations, the probability of the plant’s seed surviving and growing changes as the climate changes.McGuire explains. “Studying the dynamics of plant niches over thousands of years can help us understand how species adapt to climate change and can teach us how to protect and maintain biodiversity in the face of rapidly approaching climate change.“.
Plants and their climatic fidelity
If a plant is “climate fidelity”, it sticks to its preferred climate niche, even if that means migrating across geographic areas for thousands of years to keep up with its ideal habitat. Plants that lack this trait prefer to adapt locally to climate change, says McGuire.
The scientist and a colleague examined data from more than 13,000 fossil pollen samples taken from 337 sites across North America and divided the pollen data into six distinct 4,000-year periods starting at 18,000 years ago. His goal was to see how the climatic conditions of each tree species changed from one period to another over time.
“This process made it possible to see the climatic fidelity of these different plant taxa, demonstrating that certain plants maintain very consistent climatic niches, even when the climate changes rapidly.says Yue Wang, an associate professor at the School of Ecology at Sun Yat-Sen University in China who worked with McGuire.
For example, when North American glaciers retreated 18,000 years ago, spruce and alder trees migrated north to keep the temperatures low in their habitats. In fact, most plant species in North America have shown a trend toward climate fidelity over the past 18,000 years, says Wang.
Some species are more capable of migrating than others.
However, some species are inherently more capable of migrating than others. Willows, for example, have small seeds that can remain aloft for long distances, allowing the trees to travel farther and faster in a relatively short period of time.
However, ash trees’ large seeds can only be dispersed over short distances, hampering the trees’ ability to migrate in unison with changes in temperature.
Human-caused changes to habitats
“Human-induced habitat changes can make it even more difficult for ash trees to take root in new regions. If there are no adjacent habitats for ash trees, their seeds are under pressure to move further away, a particular challenge for ash trees, which further slows down their migratory movements.”, say the scientists in a statement about their findings.
A better understanding of plant migration could help us fine-tune conservation efforts, experts say,
“I think understanding climate fidelity, while a new and different idea, will be very important in the future, especially when thinking about how to prioritize protecting different plants from climate change.says McGuire.
“It’s important to be able to see that some plants and animals are more vulnerable to climate change, and this information can help build stronger strategies to protect the planet’s biodiversity.”.