22 “The trees of the plain shall be satisfied”: but with this grace, brought forth out of the earth. “The trees of the plain,” are the lower orders of the nations. “And the cedars of Libanus which He has planted.” The cedars of Libanus, the powerful in the world, shall themselves be filled. The bread, and wine, and oil of Christ has reached senators, nobles, kings; the trees of the plain are filled. First the humble are filled; next also the cedars of Libanus, yet those which He has planted; pious cedars, religious faithful; for such has He planted. For the ungodly also are cedars of Libanus; for, “The Lord shall break the cedars of Libanus.” For Libanus is a mountain: there are those trees, even according to the letter most long-lived and most excellent. But Libanus is interpreted, as we read in those who have written of these things, a brightness: and this brightness seems to belong to this world, which at present shines and is refulgent with its pomps. There are the cedars of Libanus, which the Lord has planted; those which the Lord has planted shall be filled....
Source: The Enarrations, or Expositions, on the Psalms (New Advent)