By Brittany Patterson
Just as the planet is being taxed from record-breaking temperatures, new research finds iconic Douglas firs across the West are water- and heat-stressed.
Similar to the humans who find themselves sluggish during a heat wave, when water is scarce, Douglas firs also put the brakes on growing — a choice that could have ramifications for forest carbon stocks and the global carbon cycle.
“If trees are being less productive, if they are not growing as well, they are taking in less CO2 from the atmosphere,” said Christina Restaino, a postdoctoral researcher at the University of California, Davis. “Tree stress can lead to the point where trees die, and when we lose tree species on the landscape, there’s always the question of what is going to grow back in its place.”
Restaino led research that examined data from more than 2,000 tree cores from 122 locations across the Western United States. The study, published this week in the journal Proceedings of the National Academy of Sciences, found increasing temperatures hurt tree growth. That’s because rising temperatures remove water from both the soil and atmosphere, causing the Douglas firs to lose water faster than they can take it in. As a result, the stressed trees close their stomata, or the tiny pores that take in carbon dioxide during photosynthesis and release oxygen as a byproduct.