White fir and Jeffrey pine trees died at the lower altitudes of their growth range in the
This study is the first to show directly the impact of climate change on a mountainous ecosystem by physically studying the location of plants, and it shows what could occur globally if the Earth’s temperature continues to rise. The finding also has implications for forest management, as it rules out air pollution and fire suppression as main causes of plant death.
“Plants are dying out at the bottom of their ranges, and at the tops of their ranges they seem to be growing in and doing much better,” said Anne Kelly, lead author of the study and a graduate student in the Department of Earth System Science at UCI. “The only thing that could explain this happening across the entire face of the mountain would be a change in the local climate.”
The study appears online the week of Aug. 11 in the Proceedings of the National Academy of Sciences. Kelly and Michael Goulden, Earth system science professor, studied the north face of the
…“I was surprised by how nice the data looked and how unambiguous the signal was,” Goulden said. “It is clear that ecosystems can respond rather rapidly to climate change.” The scientists say air pollution did not kill the trees or cause the shift because the area does not have unusually high carbon dioxide levels, and they did not observe the characteristic speckling on plants caused by ozone damage. Also, if it was pollution, all of the plants would be suffering, not just the ones at the bottom of their range. Fire suppression also is not a culprit, they say. The fire regime there is normal, with the last major fire occurring in the 1940s….
White fir trees died in the 2002 drought, while neighboring Jeffrey pines survived at this elevation. Photo from UC Irvine website