I see all white trunk trees as birch trees. But it seems there are a number of tree speies that can have white trunks.
Poplar
Populus is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar, aspen, and cottonwood. Wikipedia
Birch
A birch is a thin-leaved deciduous hardwood tree of the genus Betula, in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus Betula contains 30 to 60 known taxa of which 11 are on the IUCN 2011 Red List of Threatened Species. Wikipedia
Aspen
Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section Populus, of the Populus genus. Wikipedia
My more learned assessment is these are Aspen trees.
