A new study published in the journal Nature Plants has found that old and ancient trees provide important ecological services to forests, sustaining the ability of the entire tree population to adapt to a rapidly changing environment. Thus, instead of being only an awe-inspiring presence, such massive trees contribute evolutionary properties to forests that are vital for their long-term survival.
“We examined the demographic patterns that emerge from old-growth forests over thousands of years, and a very small proportion of trees emerge as life-history ‘lottery winners’ that reach far higher ages that bridge environmental cycles that span centuries,” said study lead author Chuck Cannon, the director of the Morton Arboretum. “In our models, these rare, ancient trees prove to be vital to a forest’s long-term adaptive capacity, substantially broadening the temporal span of the population’s overall genetic diversity.”
Together with colleagues from Tuscia University in Italy and the University of Barcelona in Spain, Dr. Cannon has found that old and ancient trees, which are often 10 to 20 times older than the average trees found in forests, contribute a vitally important amount of genetic and biological diversity to a forest’s overall population, even if they only represent one percent of that population.
Since they have survived countless environmental changes over centuries or even millennia, these trees pass their genetic resilience to their forests. Moreover, they also provide a habitat for endangered species and are capable of sequestering a larger amount of carbon than typical mature trees.
Unfortunately, climate change and deforestation practices are becoming increasingly damaging to old and ancient trees all over the world. “As the climate changes, it is likely that mortality rates in trees will increase, and it will become increasingly difficult for ancient trees to emerge in forests. Once you cut down old and ancient trees, we lose the genetic and physiological legacy that they contain forever, as well as the unique habitat for nature conservation,” explained Dr. Cannon.
While forest restoration and tree planting efforts are crucial tools for improving local and global environments, ancient trees cannot be recovered or regenerated quickly. They are an emergent property of old-growth forests which are impossible to recreate in newly regenerating forests, and must thus be protected.
According to co-author Gianluca Piovesan, an ecologist at Tuscia University, “this study recalls the urgent need for a global strategy to conserve biodiversity, not only by preserving intact forests, but in particular the small remnant of a few ancient trees that have survived in managed forest landscapes.”