A new study from Los Alamos National Laboratory shows that New Mexico’s beloved piñon pine trees may be more flexible in how they handle extreme drought than scientists once thought.
Generally, all plants have a built-in drought alarm system called a “stomatal closure point.”
When soil gets too dry, the plant hits a tipping point where it closes up to avoid dehydration. While this can help the plant survive drought, it also pauses growth and energy production.
“There are lots of trade-offs in how plants manage their water use and how they optimize water use versus photosynthesis,” said Turin Dickman, one of the LANL scientists that published the study. “They can’t have their cake and eat it too.”
Dickman and her team studied piñon pine — an “isohydric” plant that constantly works to keep its internal water levels steady, even if it means shutting down photosynthesis during extreme drought.
Scientists once thought these plants stuck to this rigid water-control strategy, come torrential rain or abundant sunshine.
But, when given more water just before prolonged drought, Dickman’s team discovered that piñon started to change, mimicking the behavior of an “anisohydric” plant – where the plant will let its water levels match the environment around it.
“It suggests that our pine forests here might be more resilient to those hot dry periods if they've experienced some wetter times just before those come along,” Dickman said.
As climate change accelerates – prolonging droughts, increasing heat waves, and sparking more frequent and intense wildfires – Dickman said the discovery could have broad implications for land managers, offering a tool to predict how ecosystems might respond to drought.
That includes thinning dense forests to reduce wildfire risk.
“Available soil water is like a bucket,” Dickman said. “When it's super dense, if you've got a lot of straws in that bucket, there's less water for each individual straw, right? If you can do some thinning, you can make more water available for those that are remaining.”
While priorities for scientific research shift heavily towards weapons modernization programs at New Mexico's scientific laboratories under the Trump administration, the LANL team has plans to look at the drought tolerance of other pine tree species if they can secure a financial sponsor.
