ecology vs preservation

ecology

noun
  • The branch of biology dealing with the relationships of organisms with their environment and with each other. 

preservation

noun
  • The act of preserving; care to preserve; act of keeping from destruction, decay or any ill. 

  • The state of being preserved, how something has survived. 

How often have the words ecology and preservation occurred in a corpus of books? (source: Google Ngram Viewer )