On its surface, Dragonquest is mostly a novel about social change (and dragons) and resisting social change (and dragons) and exploring some not-entirely-thought-out elements of its predecessor, Dragonflight (like dragons).
But Dragonquest was also written during a period of growing concerns about environmental threats—and arguments about how to handle these environmental threats. So it’s perhaps not surprising that a novel which on the surface is about duels! dragon deaths! adorable little mini-dragons! questionable gender relationships! turns out, in the end, to be about environmental threats—and arguments about how to handle them.