Climate Change Is Causing US Tree Population To Shift: Study
Rising global temperatures negatively impact all living beings. Ecologists claim that this climate change will send both animals and plants scurrying northward, or to greater altitudes in search of suitable temperatures.
However, a new study suggests that even though plants and trees are shifting their position, most are moving toward the west and not northward as previously estimated.
How The Study Was Conducted
Forest ecologists at the Purdue University in West Lafayette, Indiana, including lead author Songlin Fei and his colleagues conducted the study. The team analyzed the movement of 86 tree types using data the U.S. Forest Service had collected.
The researchers considered the data from 1980 to 1995 and again from 2013 to 2015 for all the states in the country. The researchers "measured the shifts in the centres of abundance" for these 86 tree types.
U.S. Tree Population Shifting?
The scientists found that more trees were moving toward the west rather than taking the predicted northern route. In fact, the team discovered that roughly 34 percent trees moved toward the North Pole in the last 30 years at a pace of around 6.8 miles per decade.
By comparison, 47 percent of the trees undertook a western shift in this period at speeds of around 9.5 miles per decade. The ecologists revealed that almost no tree shifted southward or eastward.
The researchers also noted that most trees which moved in the western direction were flowering plants or angiosperms, while the northbound trees were mostly gymnosperms or coniferous trees.
What Is Causing The Westward Shift?
Fei and his team posit that significant rainfall in central United States is the cause behind the westward movement of the angiosperms.
"The Southeast has had a dramatic reduction in precipitation. The western portion of the study area has more moisture available compared to the historical average," Fei explains.
The analysis and prediction of this shift in eastern forests in the United States have been difficult for scientists due to the human settlements in these areas. The presence of these settlements may be hindering the natural shift of the trees. Researchers pointed out that these forests are in the process of growing after large scale deforestation in the 1920s.
"They point out that in the eastern US it is a really tricky question to pull out climate-related changes in forests, from forests getting older and the effects of fire suppression," Leander Love-Anderegg, a tree physiologist at the University of Washington, remarked.
He added that regardless of the direction in which the trees are moving, the present-day forests will look different three or four decades down the line because of the changing climate.
The study's results are published in the journal Science Advances.