For the last several decades, we have come to believe that climate change plays a heavy hand in the rapidly changing composition of forests in the Northern Hemisphere. But scientists at the Penn State‘s College of Agricultural Sciences say that man is to blame for the altered composition of forests, not climate change.
Composition of eastern U.S. forests is changing rapidly
For instance, Minnesota forests are undergoing some major changes. Tree species characteristic to the region such as balsam fur tree and white spruce are struggling to adapt to the wet winter storms and rising temperatures. Meanwhile, tree such as red maple, black cherry, sugar maple, white oak and the American basswood have become increasingly prevalent.
According to a study published in the journal Global Change Biology, climate change is just a small factor for forest changes, at least in the eastern United States. Marc Abrams, a professor of forest ecology and physiology at the Penn State, said that these forests are still in a state of “disequilibrium,” which was caused by a large scale burning and clear-cutting in the late 18th and early 19th century.
Land-use change often trumped the impact of climate change
After analyzing the historical development of eastern forests, Abrams said that the change in types of natural and man-caused disturbances have much more significant impact than climate change. So, climate change impacts have been far less profound than previously thought. Abrams compared presettlement and current vegetation conditions in the eastern U.S.
The study revealed that the change eastern forests are experiencing is similar to the tumultuous results of European disturbances on a balanced forests system. He concluded that the altered disturbance regimes had the greatest impact on vegetation composition in the eastern U.S. over the past several centuries. However, he added that climate change too has its own influences. It just that land-use change often negated or trumped the impacts of climate change.