Oaks responded quickly to climate change in Anthropocene

Global warming has made tree adaptation and tree evolution a major concern for foresters and researchers. Researchers from INRAE (Sweden), the ONF, CEA, and the universities in Uppsala and Zhejiang, China, studied the evolution and adaptation of oak trees in three French forests over three centuries. They examined the changes that occurred from the Little Ice Age cold period to the warmer periods of human activity. Their results were published in the Journal of Environmental Research on January 6. Evolution LettersThe results show that oaks can adapt quickly to climate changes and evolve rapidly. According to these findings forest managers should reduce the time between generations and promote natural forest renewal to encourage rapid stand evolution.

The team performed a retrospective analysis of the history of oak trees from 1680 to the present, a time span that extends from the cold. Period of the Little Ice Age (1450–1850) to the warm period of the Anthropocene, from 1850 to the present day. This study was designed to understand how tree populations responded to different climates. More specifically, they sequenced and analyzed the complete genome of six hundred oak trees from three French forests (Tronçais in the Allier region, Réno Valdieu in the Perche region and Bercé in the Sarthe region) divided into four age-based cohorts: the first with an average age of 340 years, the second of 170 years, the third of 60 years and the last of 12 years. The scientists examined the variations in allele frequencies found in the genomes of each cohort. Alleles are variations in the same gene that can explain differences among trees with the same trait. Environmental selection criteria like drought or cold can affect the frequency of different alleles of the exact same gene. These variations were compared against climate change, as well as the frequency extreme events like severe droughts or winters.

Rapid evolution of oaks that adapt to changing climates

The results reveal an identical evolutionary pattern among the stands of the three forests. However, this pattern differs depending on the climatic periods. The genomes of the oldest trees are different from those of young trees during the warm period of Anthropocene. Oaks can rapidly evolve with evolutionary jumps over a few generations. They are also able to change their evolutionary trajectories quickly to adapt to climate changes.

Forest management can be adapted to encourage oak tree evolution

These results offer new insights for adapting forestManagement Climate change. They also raise the issue of maintaining trees older than 100 years, which are adapted to cold climates. This can slow down evolution by fertilizing younger trees. Shortening the generations would accelerate evolution and reduce the negative effects of poor adaptation due pollination by older stands. For more space, foresters could adapt natural regeneration techniques. evolution. Natural regeneration is seeding that occurs naturally without the intervention of humans and produces dense seedlings with over 100,000 seeds per hectare. The Trees face strong selection pressure: 95% of individual trees are eliminated in the 15–20 years that follow, and treesThe best-suited to current climate conditions will be chosen.

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INRAE