Across tens of millions of hectares in the arid and semi-arid West, pine and juniper species have recently expanded in density and in areal extent into sage and grassland ecosystems. Principle causes include deep-seated legacies of domestic livestock grazing, changes in fire regime, and climatic factors. Although PJ woodlands were technically outside of historical definitions of forest (they are not routinely measured in the USFS FIA), they are now are so ecologically important and extensive that they demand notice from natural-resource managers, policy analysts, scientists, and the public. Major soil changes are resulting from the expansion of PJ woodlands, and the topic not only offers the S7 Division an excellent opportunity to interact with Range and arid-Wildlands soil scientists, but to learn more about one of the great afforestations of our time.