Before the 19th century 'nature' was a threat to the (European) civilian rather then a place to enjoy. Since the Romantic art movement of the 19th century (e.g. see Caspar David Friedrich) 'nature' has become something to cherish and respect and even a symbol for freedom and peace.
The Flower Power hippies of the 1960's exploited the idea of nature conquering violence and repression. Iconic is the 'flower-in-gun' picture taken at the Kent State anti-Vietnam-war protests (and shootings) of 1970, an image soon adapted by the soldiers in Vietnam.