Helliconia Spring (Brian Aldiss) 1982

The text gives no sense of the grandeur and epic that the ideas deserve.  There are too many characters entering and exiting the stage whose stories are left unfinished.  When the tick that carries the helico virus is as sympathetic a character as any of the phagors, protognostics, or even most of the humans, it's difficult to see why this was a Nebula Finalist.