Climate Impacts Happening Now: Westward Migration of Forests

A recent article in The Atlantic implies climate change to be wrongly viewed as something we don’t yet know much about. This article, “American Trees Are Moving West, and No One Knows Why,” is half correct. The authors in the study reported upon reveal the reasons why trees are shifting west (as well as north), and that the shift is intrinsically related to climate change. That “No One Knows Why” these trees are shifting westward is fundamentally not a part of this research.

The authors say that the westward shift is because climate change has changed moisture patterns, that increased moisture in western portions of the eastern U.S. is the cause for this seemingly counterintuitive westward shift, and it is predominant among young trees that are more resistant to drought even in the face of sporadic drought pulses in the west. From the paper:

“The observed differential shift rates could also be due to the fact that saplings are more sensitive to droughts in terms of survival than adult trees, as substantial drought was observed in the southeastern region of the study area during the study period.”

Of critical importance to climate change awareness and the rate that we are changing our climate today, the authors tell us that these changes are happening 60 times faster than those documented in climate changes in recent prehistory.

“Similar northward shifts of clades [groups of tree species] were observed in the New England area during the early Holocene (between 10,000 and 8000 years ago), where Picea [spruce] was replaced by Pinus [pine], followed by Betula [birch] and then Quercus [oak] species. However, the historical process took place over several thousand years, whereas the observed shift in this study happened in a few decades, suggesting the impacts of recent climate change, along with other nonclimatic factors (for example, land use change and forest management), on vegetation dynamics.”

This species succession, or climate induced vegetation change, is being observed all…

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