A University of Washington-led study published May 16 in Environmental Research Lettersshows that forest die-offs in specific regions of the United States can influence plant growth in other parts of the country.
“These smaller areas of forest can have continental-scale impacts, and we really need to be considering this when we’re thinking about ecological changes,” said first author Abigail Swann, a UW assistant professor of atmospheric sciences and of biology.
The project divided the mainland U.S. into the 18 regions used in the National Ecological Observatory Network. Researchers then ran a climate model to look at what removing the existing forest cover from the 13 most-heavily-treed regions would mean for growing conditions across the country.
Of all the regions, the Pacific Southwest region, which covers most of California, has the smallest total area of tree cover. But removing those trees had the biggest influence on growing conditions nationally, by reducing vegetation in the Eastern U.S.
The precise mechanisms would require further study, Swann said, but in this case it seemed to make Eastern summers slightly warmer, which was harmful to plant growth.
“Forest loss is disrupting or changing the flow patterns in the atmosphere that is leading to a slightly different summertime climate in the eastern part of the country,” Swann said. “It’s very analogous to El Niño or ‘the blob,’ something that’s occurring that causes the atmosphere to move around, which causes these warmer or cooler conditions, or wetter and drier conditions, somewhere else.”
“There’s some pretty extensive, widespread forest loss going on,” Swann said. “The changes we made in the model are bigger, but they’re starting to converge with things that we’re actually seeing.
“These results show that we need to start thinking about how altering vegetation in one place can affect plants elsewhere, especially in the context of climate change.”
Read the entire article in UW Today.