Trees that were once able to survive small forest fires may now have a harder time thriving after a blaze, according to scientists at the U.S. Geological Survey. This is due to warmer temperatures and dryness that weaken trees’ ability to take up water over the long term.
Though the trees studied, mostly in the U.S. West, are used to heat and drought, the prolonged heat they’ve experienced in recent times is most likely the reason they’re more vulnerable. Experts say it appears that the consistently warmer temperatures and dryness can create air bubbles inside trees that block the passage of moisture.
Trees are comprised of tubes going from the roots up to the leaves. Water is taken up through the tubes and circulated as needed. When a bubble blocks a tube, water simply can’t be pulled through it anymore. Over time, drought conditions can increase the number of air bubbles, drying out and weakening trees.