Seven common European forest tree species have managed to maintain significant genetic diversity over millions of years, even as they weathered drastic environmental changes during ice ages.
A recent study by a European research consortium, led by Uppsala University and published in Nature Communications, suggests these trees’ adaptability could be a crucial factor in supporting biodiversity under modern climate stressors.
“From a biodiversity perspective, this is very positive because these trees are keystone species on which many other species depend,” said Pascal Milesi, Associate Professor of Plant Ecology and Evolution at Uppsala University and the study’s first author.
The research team, comprised of scientists from 22 European institutions, analyzed the genetic makeup of seven widely distributed tree species: European beech (Fagus sylvatica), Maritime pine (Pinus pinaster), Sessile oak (Quercus petraea), Silver birch (Betula pendula), Scots pine (Pinus sylvestris), Norway spruce (Picea abies), and Black poplar (Populus nigra). They collected and examined DNA from nearly 3,500 trees across 164 European locations, with the findings revealing these species’ unexpected genetic robustness.
Surviving the Ice Age
The study’s focus was to uncover how the trees’ genetic diversity had evolved through the Earth’s cycles of warm and cold periods, particularly during the last ice age approximately 10,000 years ago. Despite expectations of diminished diversity due to range restrictions and population losses during these periods, the results showed the opposite.
According to Milesi, the high genetic diversity can be attributed to two unique characteristics: the long generation times of trees and the capacity for tree pollen to travel over great distances, sometimes thousands of kilometers.
“We believe the reason for this high genetic diversity is related to the way these tree species survived through the ice ages and to fact that tree pollen can travel thousands of kilometres, bringing together trees that grow far apart,” Milesi explained. “This is a welcome sign. The evolutionary processes that were at play in the past may also be useful to cope with today’s rapid climate change.”
The pollen’s ability to traverse vast areas enabled tree populations to maintain genetic exchange across their ranges, contributing to their resilience. This adaptability has allowed the trees to withstand environmental pressures and sustain their role as foundational species, essential for various ecosystems.
In Sweden, the research centered on three key species: Norway spruce, Scots pine, and silver birch. These trees are not only ecologically significant but also economically vital, representing the majority of Sweden’s forests and forming the backbone of the timber industry. Norway spruce and Scots pine are particularly valued for their contributions to forestry, and all three trees provide essential habitats for diverse flora and fauna.
“Due to the sixth mass extinction event and the ongoing biodiversity crisis, people can easily get the feeling that it is too late and be ready to give up. This study sends a positive signal about our forest and provides important information to help manage forest biodiversity in the face of climate change,” Milesi said, highlighting the potential for these findings to inform conservation and forest management strategies.
The species studied are: Fagus sylvatica (European beech), Pinus pinaster (Maritime pine), Quercus petraea (Sessile oak), Betula pendula (Silver birch), Pinus sylvestris (Scots pine), Picea abies (Norway spruce) and Populus nigra (Black poplar).
Lessons for a changing climate
As climate change accelerates, the study’s authors believe that understanding how these species preserved their genetic diversity over millennia offers valuable insights. If forests were able to survive past climate shifts, the mechanisms that allowed them to do so might provide clues for enhancing resilience in today’s rapidly changing environment.
Though trees cannot escape their environment, their genetic diversity, driven by long generation times and widespread pollen dispersal, offers a buffer against change. This ability to hold on to genetic resources over time suggests that trees could adapt to future conditions if they’re given enough time and resources. Conservation efforts that protect the forests and their genetic diversity are crucial, especially given their ecological roles as keystone species.
These findings underscore the resilience of Europe’s forests in the face of both ancient and modern climate challenges. With the right strategies, the adaptability of these tree species could help to mitigate the impacts of climate change on biodiversity and ensure the continued vitality of forest ecosystems.
Journal Reference:
Milesi, P., Kastally, C., Dauphin, B. et al. ‘Resilience of genetic diversity in forest trees over the Quaternary’, Nature Communications 15, 8538 (2024). DOI: 10.1038/s41467-024-52612-y
Article Source:
Press Release/Material by Uppsala University
Featured image credit: Daniel Peters | Unsplash
