Saturday, May 26, 2018


On my flight from Denver to Washington, DC, today, trees were a reliable indicator of the regional climates.  Across the semiarid High Plains, spotty groves of trees were observed along dry stream beds or surrounding farmhouses but were otherwise absent.  Farther east, the green ribbon of the Platte River snaked across southern Nebraska, demonstrating a steady supply of water for plains cottonwoods and other riparian trees and shrubs.

The riverine corridors thickened after we crossed the Missouri River (just south of Omaha) as the size and number of the streams increased, fed by abundant moisture from the Gulf of Mexico.  After flying over the Illinois River at Peoria, trees diminished once again across the Glaciated Plain of central Illinois; once a vast prairie, it is now productive farmland, studded with wind farms.  Clouds obscured the landscape over most of Indiana and Ohio and, when breaks in the overcast finally returned, a sea of trees stretched below us, indicating that we had reached the forests of the Appalachian Plateau.  In this geophysical province, trees must be cleared for homesteads and cropfields are primarily limited to the valley floors .

Descending through low clouds to Dulles International Airport, we followed the Potomac River down from the Plateau and across the relatively flat landscape of the Piedmont.  The Washington Monument, well to our southeast, shimmered in sunlight as we glided above a mosaic of woods and wetlands, broken by small farms and the sprawling suburbs of Northern Virginia.  Trees do just fine in the relatively mild, humid climate of the Mid-Atlantic region.