Trees in eastern U.S. shift­ing north, west for cooler weather

Honolulu Star-Advertiser - - NATION & WORLD - By Seth Boren­stein

WASH­ING­TON >> A warmer, wetter cli­mate is help­ing push dozens of eastern U.S. trees to the north and, sur­pris­ingly, west, a new study finds.

The eastern white pine is go­ing west, more than 80 miles since the early 1980s. The eastern cot­ton­wood has been head­ing 77 miles north, ac­cord­ing to the re­search, based on about three decades of for­est data. The north­ward shift to get to cooler weather was ex­pected, but lead au­thor Songlin Fei of Pur­due Univer­sity and sev­eral out­side ex­perts were sur­prised by the move to the west, which was larger and in a ma­jor­ity of the species.

New trees tend to sprout far­ther north and west while the trees that are far­ther south and east tend to die off, shift­ing the ge­o­graphic cen­ter of where trees live. Think of it as a line of peo­ple stretch­ing, said Fei. De­tailed ob­ser­va­tions of 86 dif­fer­ent tree species showed, in gen­eral, the con­cen­tra­tions of eastern U.S. tree species have shifted more than 25 miles west and 20 miles north, the re­searchers re­ported Wednes­day in the jour­nal Science Ad­vances.

One of the more strik­ing ex­am­ples is the scar­let oak, which in nearly three decades has moved more than 127 miles to the north­west from the Ap­palachi­ans, he said. Now it’s re­duced in the South­east and more pop­u­lar in the Mid­west.

“This anal­y­sis pro­vides solid ev­i­dence that changes are oc­cur­ring,” former U.S. For­est Chief Michael Dombeck said in an email. “It’s crit­i­cal that we not ig­nore what analy­ses like these and what science is telling us about what is hap­pen­ing in na­ture.”

The west­ward move­ment helped point to cli­mate change — es­pe­cially wetter weather — as the big­gest of many cul­prits be­hind the shift, Fei said. The re­searchers did fac­tor in peo­ple cut­ting down trees and changes to what trees are planted and where, he said. With the South­east gen­er­ally dry­ing and the West get­ting wetter, that ex­pla­na­tion makes some sense, but not com­pletely, said Brent Sohn­gen at Ohio State Univer­sity, who was not in­volved in the study.

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