Method used to predict how trees adapt to climate change is flawed: Study

With the rising impact of climate change, there is an increasing urgency for species to migrate, adapt or go extinct. For decades, scientists have used a specific method to predict how a species will survive during this time. Now, a new study shows that the age-old method might be flawed.

This study, led by researchers from the University of Arizona, team members at the U.S. Forest Service, and Brown University found that the space-for-time substitution, a key method used to predict how species might adapt to changing climate conditions, might be producing misleading results. 

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According to a press statement, space-for-time substitution assumes that individuals growing at the hotter end of climate conditions can serve as an example of what might happen to populations at cooler locations in a warmer future.

For this study, the researchers focused on a widespread tree species found in the western regions of the United States, called the ponderosa pine, which has responded to the last several decades of warming. The team collected and analysed ponderosa pine tree rings from as far back as 1900 and compared the actual growth to how the model predicted the trees should respond to warming, the statement revealed. The findings were published in the Proceedings of the National Academy of Sciences.

The researchers found that space-for-time substitution predictions are wrong in terms of whether the response to warming is a positive or negative one. While the method predicts that ponderosa pines should benefit from warming, in reality, they are negatively impacted.

"These spatially based predictions are really dangerous because the spatial patterns reflect an end point after a long period of time when species have had a chance to evolve and disperse and, ultimately, sort themselves out on the landscape," study author Margaret Evans explained in the statement. Climate change, however, works differently. Often, trees are in a situation where change is occurring faster than the trees can adapt, which puts them at risk of going extinct. These findings are a word of caution for ecologists, Evans adds.

The research team also looked at how trees respond to rainfall and the findings indicated that more water is always better, considering both time and space.

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