Confronted with Wildfire Smoke, These Trees Stop Breathing

Scientists have discovered that ponderosa pines effectively stop breathing when beset by wildfire smoke.

The finding helps clarify the impact of wildfire smoke, which has been difficult to study, as scientists cannot predict when fires will break out and must take caution when working near blazes.

In the fall of 2020, scientists from Colorado State University got lucky. They were studying how trees in the Rocky Mountains emit the compounds that lend forests their piny aroma when heavy smoke from a nearby fire settled over the research site. With equipment ready, they were able to measure the smoke’s impact.

Scientists found that, amid the haze, ponderosa pines closed the tiny pores on the surface of their leaves, which allow them to take in carbon dioxide and release oxygen. When pores closed, photosynthesis came to a halt. The findings were published in Geophysical Research Letters.

Writing in The Conversation, study authors concluded that “some plants respond to heavy bouts of wildfire smoke by shutting down their exchange with outside air. They are effectively holding their breath, but not before they have been exposed to the smoke.”

Authors speculated that smoke may be clogging pores or preventing them from opening. It may also be that leaves are closing their pores at the first sign of smoke in an act of self-preservation.