The Carnegie Institution for Science has announced that researchers have discovered that the recent die-off of Colorado trembling aspen trees is a result of both decreased precipitation and increased summer temperatures.
The die-off, which affected 17 percent of Colorado aspen forests, was initiated by drought conditions from 2000 to 2003. The drought stifled the trees’ ability to transport water to their leaves, resulting in stagnant growth and increased mortality that persisted for a decade after the drought.
Researchers were able to pinpoint the cause of the die-off by examining the ratio of oxygen isotopes in trees’ veins. Oxygen isotopes show when and how water was absorbed, allowing researchers to locate the factors responsible for the decline.
Image: Trembling aspen tree (Credit: USDA)