Tree Migration: British Columbia Study Update

Tree Migration: British Columbia Study Update

New research from the University of British Columbia suggests evolution is a driving mechanism behind plant migration, and that scientists may be underestimating how quickly species can move.

The study, published July 28 in the journal Science, builds on previous research that has shown some plants and animals are moving farther north or to higher altitudes in an effort to escape rising global average temperatures due to climate change.

Artificial Migration of Trees

New research from the University of British Columbia suggests evolution is a driving mechanism behind plant migration, and that scientists may be underestimating how quickly species can move, according to a UBC press release July 28.The study, published today in the journal Science, builds on previous research that has shown some plants and animals are moving farther north or to higher altitudes in an effort to escape rising global average temperatures due to climate change.

Seed Dispersal

For the study, researchers used a small flowering plant (Arabidopsis thaliana), a common model organism in plant biology, to test the role of evolution in plant migration. Individual plants with different traits were cultivated together to create two sets of populations, one in which evolution was acting and another in which evolution was stopped.

They found that, after six generations, evolving plant populations dispersed seeds and migrated 11 per cent farther than non-evolving populations in landscapes with favourable conditions. Meanwhile, in landscapes where conditions were more challenging for the plants to disperse seeds, the evolving plant populations spread 200 per cent farther.
 

“We know from previous research that evolution might play a role in how fast a species can move across a region or continent,” said Jennifer Williams, the study’s lead author and an assistant professor in UBC’s department of geography. “But what our study suggests is that evolution is not only a factor in movement, but that it can, in fact, accelerate” the spread, and can do so predictably.

Jennifer Williams
Lead Author, Assistant Professor in UBC’s department of geography

Evolution Accelerates Speed Migration

The findings suggest that evolution accelerates the speed of migration, said Williams.

However, more research is needed to determine why the researchers saw a larger effect of evolution under the more challenging conditions, which in this case increased the speed of movement.

Williams said the findings underscore the importance for scientists to account for evolutionary change when predicting how quickly native species will be able to move as the Earth’s climate continues to warm.

The study was co-authored by Bruce Kendall of the University of California, Santa Barbara, and Jonathan Levine of the ETH Zurich.

US Study: Assisted Migration Could Help Save Forests

The USDA Forest Service estimates that 97 per cent of the whitebark pine’s natural range will disappear by 2100 in the US.

The strategy that might save whitebark pines in the long run is one that’s been discussed for decades among ecologists and is only now gaining traction: assisted migration. That basically means planting tree seeds in areas where they will be able to survive in the future.

“If we keep the status quo and not move stuff around, we run the risk of losing populations or species,” said Laura Gray-Steinhauer, who researches climate change adaptation strategies at the University of Alberta to The Verge Monday.

Most trees don’t move at all (though some do), and they take a long time — sometimes even 30 years or more — to start producing seeds. Seeds don’t move on their own, either; they rely on the wind or animals like birds and squirrels to move around. While that might give an advantage to poplar seeds, which are light, it creates problems for large, heavy seeds like those produced by Torreya taxifolia, an endangered conifer.

Danger of Translocated Species Becoming Invasive

Many ecologists worry that translocated species might become invasive. In the US alone, invasive plant species cost an estimated US$120 billion a year, according to the Nature Conservancy.

Trees are also homes for a lot of creatures, including bugs and fungi. Moving trees means also moving this entire household of potential pests. Fungi can infect other plants and end up wiping out other trees. “We’re not moving species into vacuums, we’re moving them into communities where other species exist,” says Mark Schwartz an ecologist at the University of California, Davis. “Engaging in the intentional moving of species for the conservation benefits is likely to have cases where we also cause unintended damage.”

Canada and US Efforts

In Canada, some assisted migration programs are already underway, but they’re done a bit more cautiously. In British Columbia, for example, the western larch is being migrated north, outside of its range. But when an area is planted, only 10 per cent of the trees can be western larch, says Aitken. That’s to be on the safe side: if the western larches don’t survive, the other trees will eventually occupy their space. If they do, they won’t be able to take over.

In the US, forest managers are considering a less controversial form of assisted migration that has to do with seed selection, according to Christopher Woodall, a research forester at the Forest Service. Instead of moving trees north, forest managers are selecting seeds of the same tree species that live in warmer climates and are therefore more resistant to droughts.

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