I'll answer your question concerning Shelley's Frankenstein by looking at a different element or side of nature.
Nature vs. Nurture is a central theme in the novel. Left to himself, without nurturing from his creator/father, the creature turns into the monster. Victor fails his responsibility to take care of, to nurture, that which he creates.
The wild, natural man, then, does not turn out so well. Victor rejects him largely due only to his appearance. As a result of this rejection, the creature suffers from isolation, loneliness, emotional deprivation, and eventually becomes a monster.
Unusually, and perhaps ironically, the creature, left to fend for himself in the world of nature so emphasized by other romantic writers, does not absorb its goodness or touch the transcendent or commune with it and experience transformation as in, for instance, Wordsworth's "Tintern Abbey." Nature does not lead the monster to acts of kindness. His isolation leads to acts of horror.
One needs to look at the topic in general in the book Frankenstein to figure out the relevance of nature. First Victor loses his mother to the natural experience of death. Next Victor goes against ethical mores by creating a human being.
Nature plays an important role in the creation of the human because it is during with the help of lightening that the heart is charged to life. He harnesses the power of nature to create life.
When the creature is rejected he retreats to nature for protection. He hides in the cave and observes the beauty of the world. His connection with nature is shows the human connection to mother earth and introduces the reader to a more gentle side of the creature.
After Victor refuses to help him by making a mate, the creature retaliates. He finally knows that he can not be among people because he is a hideous outcast. He uses nature to isolate himself by going to the far ends of the earth. The ice and frozen area reflect the isolation of the creature emotionally and physically. It is only fitting that Victor who created him from fire should die in the kingdom of ice.