The area between or behind the high sand dunes along the Pacific ocean is not referred to as the interdunal area. If it were one could say that shore pine is an interdunal species. “Foredune” is a better term: A great swathe of shore pine and mixed evergreen shubs colonize the foredunal area.
Lodgepole pine and shore pine are considered to be different varieties of the same species. The former grows at high elevations and the latter in boggy costal areas. Often shore pine is swept by ocean winds into low and asymetric forms.