WASHINGTON, May 17 (Xinhua) -- Climate change has long been predicted to shift trees northward, but a new study released on Wednesday found that it's also causing some tree species to move westward in the eastern United States.
The study, led by Purdue University professor Songlin Fei and published in the U.S. journal Science Advances, used the U.S. Forest Service data on 86 tree types to explore the distribution of these trees in the eastern U.S. between 1980 and 2015.
Many climate change studies have generally shown a strong correlation between changes in temperature and tree shifting, but the new study was surprised to find that precipitation has a stronger near-term impact on the ranges of many tree species than temperature.
"Trees are shifting partially because of climate change, but their responses are species specific," Fei said. "Deciduous trees like oak and maple are primarily moving westward. Evergreens are responding in a different way. They're moving northwards."
Deciduous trees were shifting westward to follow changes in moisture, he explained, pointing to an increase of more than 150-mm total annual precipitation in the central United States and a large reduction in the southeast during the 30-year study period.
Fei said the findings are significant in that the research shows the clear impact of climate change based on big data, not just modeling.
"It is not future predictions," he said. "Empirical data reveals the impact of climate change is happening on the ground now. It's in action."