Global wind patterns could impact forests’ abilities to adapt to climate crisis, research suggests

Forests’ futures are blowin’ in the wind

Harry Cockburn
Tuesday 11 May 2021 18:22
Researchers have discovered correlations between wind direction and genetic diversity in forests
Researchers have discovered correlations between wind direction and genetic diversity in forests

Trees may be rooted to the spot, but over decades and centuries, tree species do move - through the dispersal of their seeds and pollen.

New research suggests that some species of trees, and even whole forests’ abilities to survive and adapt to the worsening climate crisis could partly depend on the eddies and swirls of enormous global wind currents which play a role in seed and pollen dispersal.

The research, by scientists at the University of California, compared existing global wind patterns with previously published genetic data of nearly 100 tree and shrub species collected from forests around the world.

The research team found “significant correlations between wind speed and direction and genetic diversity throughout our planet’s forests”.

The findings are the first to suggest that wind may not only influence the spread of an individual tree or species’ genes, but can also help shape genetic diversity and direct the flow of genetic variation across entire forests and landscapes.

Understanding how genetic variants move throughout a species range will become increasingly important as the climate crisis alters the conditions of local habitats, the researchers said.

“How trees move and how plants move, in general, is a big area of uncertainty in plant ecology because it’s hard to study plant movements directly,” said study lead author Matthew Kling, a postdoctoral researcher in integrative biology at UC Berkeley.

“They happen as a result of small, rare movements of seeds and pollen.

“However, to predict how species distributions, and plant ecology, in general, will respond to climate change, we need to understand how these species are going to be able to move long distances to track the movement of natural resources and climate conditions over time.”

It is not just wind which distribute and disperse seeds and pollen for trees, as mammals, birds and insects also play huge roles in this process, however wind’s “strong directionality” makes it a key aspect for understanding how trees will respond to the changing conditions thrown at them by climate breakdown.

Study senior author David Ackerly, a professor and dean of UC Berkeley’s Rausser College of Natural Resources said: “As the world warms, many plants and animals will need to move to places with suitable habitat in the future to survive.

“Wind dispersal has a particularly interesting connection to climate change because wind can either push the genes or organisms in the right direction, toward more suitable habitat, or in the opposite direction. It may be the only terrestrial dispersal vector that can be aligned with or against the direction of climate change.”

Though daily weather conditions are highly changeable, large-scale global wind patterns are strongly impacted and determined by Earth’s shape, rotation and the locations of the continents.

What’s more, these patterns are believed to be relatively stable over millennial time-scales, and researchers currently believe they are still unlikely to be dramatically altered by the climate crisis, Dr Kling said.

To examine whether these global prevailing winds have shaped the genetic diversity of modern-day forests, Dr Kling compared current planetary wind models - compiled from 30 years of global wind data - with genetic data from 72 publications covering 97 tree and shrub species and 1,940 plant populations worldwide.

He identified three key ways global wind patterns shape forests’ genetic diversity.

Firstly, tree populations connected by stronger wind currents tend to be more genetically similar than tree populations which are not as connected. Second, tree populations which are downwind, or further in the direction that the wind blows, tend to show more genetic diversity in general. Finally, genetic variants are more likely to disperse in the direction of the wind.

For example, the island scrub oak tree is a native to the Channel Islands in Southern California, where prevailing winds tend to blow to the southeast.

Dr Kling’s analysis showed that scrub oak populations on islands connected by higher wind speeds are more genetically similar to each other. Genetic variants also appear to have dispersed more frequently to the islands in the southward and eastward directions than the reverse, leading to greater genetic diversity to the south and east.

Dr Kling hopes that recognising these patterns will help conservationists and ecologists better understand how well tree and plant species in different regions of the globe will adapt to a warming world.

“Populations in different portions of a species range have evolved over time to be well-adapted to the climate in that specific part of the range, and as climate changes, they can become out of sync with those conditions,” Dr Kling said.

“Understanding how quickly genetic variants from elsewhere in the species range can get where they are needed is important for understanding how quickly the species will respond to climate change, and how vulnerable, versus resilient, a given population might be.”

The research is published in the Proceedings of the National Academy of Sciences.

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