Climate change and habitat destruction are driving species to extinction at an alarming rate. This crisis impacts all taxonomic groups, including mammals, birds, and plants.
Over the past 500 years, extinction rates have surged beyond natural levels, ranging from 150 to 260 extinctions per million species years (E/MSY). This rate is a stark contrast to the background extinction rate of 0.1–1 E/MSY, indicating a significant crisis.
While mammals have historically faced the greatest extinction pressure, plants are also disappearing at unprecedented rates. Nearly 20% of plant species are now threatened by the International Union for Conservation of Nature (IUCN). Plant extinction rates range from 18 to 26 E/MSY, surpassing 500 times the natural rate. Many plant species may persist unnoticed in dormant seed banks, adding to the uncertainty.
Regions with high biodiversity suffer the most extinctions. While plant extinctions are rare in boreal and arctic regions, these areas are crucial testbeds for studying species loss under natural climate fluctuations.
How Plants Respond to Environmental Change
Understanding plant vulnerability to extinction is complex. Species at the edges of their native ranges or highly specialized to particular habitats face greater risk. However, rarity does not always equate to vulnerability.
Plant size and seed production significantly influence survival, but no clear evolutionary pattern links to extinction. Plant extinction studies rely heavily on pollen analysis, which lacks species-level detail, unlike the detailed fossil records available for mammals.
To track plant extinctions, researchers analyze species occurrences across regions. However, long-term, multi-site datasets at high taxonomic resolution are lacking, often identifying plants only to the family or genus level.
New genetic techniques, such as sedimentary ancient DNA (sedaDNA) analysis, offer a promising solution. This method can reconstruct plant community changes over thousands of years, revealing significant biodiversity shifts due to climate change.
Lessons from the End of the Last Ice Age
Research from the Alfred Wegener Institute (AWI) provides critical insights into climate-driven plant extinctions. By analyzing ancient plant DNA in lake sediments from Alaska and Siberia, scientists reconstructed vegetation changes from 15,000 to 11,000 years ago—the period marking the end of the last ice age.
“Everyone knows that the woolly mammoth went extinct, but virtually no one mentions the plants that were lost at the end of the last ice age,” says Ulrike Herzschuh, a lead researcher at AWI. “Until recently, we lacked suitable methods for investigating plant species extinctions in detail.”
Sequencing DNA fragments from lake sediments revealed when and where plant species appeared and disappeared. Key findings indicate a crucial link between climate and plant interactions.
During cold periods, plants supported one another, creating microhabitats that helped species survive. However, rising temperatures intensified competition, leading to a decline in plant diversity.
Cushion plants, for example, provided shelter in harsh climates. In today’s Arctic, however, they face accelerated extinction as woody plants spread, outcompeting cushion plants and exacerbating biodiversity loss.
Predicting Future Plant Extinctions
Extinction patterns from the end of the last ice age offer clues about which species are most vulnerable today. Grass and shrub species face higher risks than trees, which can migrate more easily with rising temperatures. Highly biodiverse regions are particularly at risk as species struggle to compete in rapidly changing environments.
Extinction rates peaked early in the current warm period, sometimes with a delay of thousands of years after initial climate shifts. This suggests that the full impact of today’s activities may not be evident for centuries.
