Why does it say "l'Dor va'Dor Emunasecha Konanta"?
Radak: Even though the legions of the land do not last 1 , Your Emunah is established. It is the existence of the world; You prepared that it endure forever. "L'Dor va'Dor" is like "Dor Holech v'Dor Ba" (Koheles 1:4).
Malbim: "L'Dor va'Dor" hints that progeny of the land perish; there is a difference between past generations and new generations. Even so, Your Emunah stands - the promise that the species will not cease - "Oseh Pri l'Mino", "Peru u'Rvu" (Bereishis 1:11, 22).
I.e. creations that dwell on the land, they die; refer to 118:90:2:1. (PF)
What is the meaning of "Eretz va'Ta'amod"?
Radak: You decreed that the legions of Shamayim last forever, but the legions of the land, individuals pass, but the Kelalim persist - "veha'Aretz l'Olam Omades" (Koheles 1:4).
